The Octopus, the Dolphin and Us: a Great Filter tale

by Stuart_Armstrong3 min read3rd Sep 2014236 comments


EvolutionGreat FilterGeneral Intelligence

Is intelligence hard to evolve? Well, we're intelligent, so it must be easy... except that only an intelligent species would be able to ask that question, so we run straight into the problem of anthropics. Any being that asked that question would have to be intelligent, so this can't tell us anything about its difficulty (a similar mistake would be to ask "is most of the universe hospitable to life?", and then looking around and noting that everything seems pretty hospitable at first glance...).

Instead, one could point at the great apes, note their high intelligence, see that intelligence arises separately, and hence that it can't be too hard to evolve.

One could do that... but one would be wrong. The key test is not whether intelligence can arise separately, but whether it can arise independently. Chimpanzees, Bonobos and Gorillas and such are all "on our line": they are close to common ancestors of ours, which we would expect to be intelligent because we are intelligent. Intelligent species tend to have intelligent relatives. So they don't provide any extra information about the ease or difficulty of evolving intelligence.

To get independent intelligence, we need to go far from our line. Enter the smart and cute icon on many student posters: the dolphin.

Dolphins are certainly intelligent. And they are certainly far from our line. It seems hard to find a definite answer, but it seems that the last common ancestor of humans and dolphins was a small mammal existing during the reign of the dinosaurs. Humans and dolphins have been indicated by red rectangles, and their last common ancestor with a red circle.

This red circle is well before the K-T boundary (indicated by the dotted line), hence represents a mammal living in the literal shadow of the dinosaurs.

We can apply a convergent evolution argument to this common ancestor. Thus, assuming that subsequent evolution was somewhat independent, getting from that common ancestor to dolphin level of intelligence is something that can happen relatively easily.

Can we go further? Well, what if we applied the argument twice? Let's bring in the most alien looking of the high-intelligence animals: the octopus.

Let's make the further assumption that our common ancestor with dolphins was dumber than the modern octopus. This doesn't seem a stretch seeing how intelligent the modern octopus can be, how minor in terms of ecological role the common dolphin-human ancestor must have been, and seeing the stupidity of many of the descendants of that common ancestor.

If we accept that assumption, we can then start looking for the common ancestor of humans and octopuses. Our two species are really far apart:

We therefore have to go back to around the last common ancestor of the Bilateria (creatures with bilateral symmetry, i.e. they have a front and a back end, as well as an upside and downside, and therefore a left and a right). This is the (speculative) urbilaterian. There are no known examples or fossils of it, which means that it was likely less than 1 cm in length. To quote Wikipedia: "The urbilaterian is often considered to have possessed a gut and internal organs, a segmented body and a centralised nervous system, as well as a biphasic life cycle (i.e. consisting of larvae and adults) and some features of embryonic development. However, this need not necessarily be the case." Very confusing, and with no information about intelligence level. However, since the organism was so small and since it was the ancestor of almost every animal alive today (including worms and Bryozoa), our best estimate would be that it's pretty stupid, with the simplest possible "brain".

Putting this all together, it seems evolutionarily easy to get from urbilatrian intelligence to Octopus intelligence, and from Octopus intelligence to dolphin intelligence - thus from urbilatrian to dolphin.

Note that this argument assumes that intelligence can be put on something like a linear scale. One could argue that Octopuses have low social intelligence, for instance. But then one could repeat the argument with distant animals with high social intelligence such as certain insects. Especially if one believe in a more general form of intelligence, it seems that this family of arguments could be used effectively to demonstrate dolphin-level intelligence emerging easily from very low levels of intelligence.


Application to the Great Filter

The Great Filter (related to the Fermi Paradox) is the argument that since we don't see any evidence of complex technological life in the universe, something must be preventing its emergence. At some point on the trajectory, something is culling almost all species.

An "early" great filter wouldn't affect us: that means that we got through the filter already, it's in our past, so the emptiness among the stars doesn't say anything negative for us. A "late" great filter is bad news: that implies that few civilizations make it from technological civilization to star-spanning civilization, with bad results for us. Note that AI is certainly not a great filter: an AI would likely expand through the universe itself

The real filter could be a combination of an early one and a late one, of course. But, unless the factors are exquisitely well-balanced, its likely that there is one location in civilizational development where most of the filter lies (ie where the probability of getting to the next stage is the lowest). Some possible locations for this could be:

  • Life itself is unlikely (very early great filter).
  • Life with a central nervous system is unlikely.
  • A lot of different possible locations for the great filter in between urbilatiran and dolphin intelligence.
  • Getting from dolphin to human intelligence is unlikely.
  • Getting from human intelligence to technological civilization is unlikely (latest early filter).
  • Getting from technological civilization to star-spanning civilization is unlikely.

These categories aren't of same size, of course - the first three are very diverse and large, for instance. Then what the evolutionary argument above says, is that the Great Filter in unlikely to be in the third, bolded category (which is in fact a multi-category).

For what it's worth, my personal judgement is that the filter lies before the creation of a central nervous system.



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I don't think filters have to be sequential - some could be alternatives to each other, and they might interact. Consider the following.

Each supernova sterilizes everything for several lightyears around them. This galaxy has three supernovas per century, and it used to have more. Earth has gone unsterilized for 3.6 billion years, i.e. each of the last (very roughly) 100 million supernovas was far enough away to not kill it.

That's easy to do for a planet somewhere on the outer rim, but the ones out there seem to lack heavy elements. If single-celled, mullti-celled, even intelligent life was easy given a couple billion years of evolution, you still couldn't go to space on a periodic table that didn't contain any metals.

So planets in areas with lots of supernova activity (i.e. high density of stars) could simply never have enough time between sterilizations to achieve spacefaring civilization, while planets in areas with low density of stars/supernovas haven't accumulated enough heavy elements to build industry and spaceships. Neither effect prohibits everything, but together they're a great filter.

There could be other combinations of prohibitive factors, where passing one makes passi... (read more)

Really-quick-and-dirty calculation time!

Let's say 3 supernovas per century and each sterilizing 10 light years in radius.

That produces an average sterilization volume of about ten cubic light years per year. Total volume of the galactic thin disc is on the order of 2*10^13 cubic light years. That produces a half life of sterilization on the order of trillions of years, though you can bring it down to billions if you increase the supernova rate by a factor of a thousand or increase sterilization radius out to 100+ light years.

We can probably discount the galactic core for any purposes though - I've seen fun papers proposing evidence that it undergoes periodic starbursts every few tens of millions of years and the galactic supernova rate then briefly goes up to something like one per year with most of them in the core.

Thanks, but it appears we're both wrong. Here is a nice intro article that gives proper numbers on this very subject and concludes supernovae aren't a life-forbidding problem even in the galactic center.

But high density of stars might lead to planetary orbit perturbations which could be. It appears the galaxy is a bit complicated.

7[anonymous]6yBTW, this recently showed up on arXiv: (“At z > 0.5” approximately means [] ‘more than 5 billion years ago’.) (I only have read the abstract so far.)
2chaosmage6yVery interesting, thank you! I especially like the insight that for evolution to go on uninterrupted for 5 billion years, you don't just need a particular type of planet (not hot, not cold, in a stable orbit) in a particular region of the galaxy (on the outskirts), but this planet also needs to be inside a particular type of galaxy (big, old, not dense) that happens to be in a particular type of intergalactic environment (not dense, lacking low metallicity dwarf galaxy neighbors). This helps with the sharper version of the Fermi paradox that assumes the possibility of intergalactic travel. I'm not a physicist, but as far as I understand the paper, their assumption of what constitutes a "lethal" amount of Gamma Ray Burst damage to a planet seems kind of arbitrary. Their description indicates that it'd kill everything on the surface and everything underwater that feeds on plankton. But I see nothing to indicate that, say, life on hydrothermal vents, or bacteria living deep underground (which exist on our planet at least two miles down) couldn't survive what the authors call "lethal". So abiogenesis would not need to happen again in those cases, nor would evolution of very basic metabolic structures that evolution would again build upon. Even a small bunch of tiny replicators that survived with, say, three billion years of previous evolution under their belt might re-colonize the planet much more quickly and diversely than newly arisen ones could. Meaning that as a layman, I don't see how we'd distinguish between a past where Earth was hit by a "lethal" GRB 2 billion years ago (when there were just eukaryotes, procaryotes and cyanobacteria), and one were it wasn't.

Actually, I'm not a layman, and I have some ideas.

The Proterozoic (2 billion years ago) is a time period that geologists affectionately call the 'boring billion'. In those rock strata, we very often find biogenic stromatolites, crumpled accretionary structures produced by the accumulation of mineral waste products in microbial metabolism. In the wild, they look like lumpy rocks on coastlines and in lakes, with a thin biofilm on top. Think of them as the microbial forests through which the early eukaryotes would have foraged and hunted. These ecosystems are also exclusively shallow-water, since they require sunlight and water in copious supply.

As such, they would be wiped out by a 'moderate' gamma ray burst, since they don't have the protection of deep oceans. In other words, there would be a specific moment at which accretion halted for every biogenic stromatolite at the same time. This would be followed, in geologic history, by a shortish period in which newly lithified sediments lacked a biological influence, as life clawed its way back from the deep oceans. Even if the biosphere that followed was indistinguishable from the previous incarnation (which itself seems unlikely... (read more)

2[anonymous]6yIndeed, according to Wikipedia at least, we don't know whether the Ordovician–Silurian extinction event was caused by a GRB or not.
4private_messaging6yA much more plausible filter, along the same lines, is earth not ever going outside a certain range of temperatures, over four billions years or so, as Sun shone brighter. There could be many filters along the same lines, such as never happening evolution of a very successful but simple organism that eats everything complex, prompting a restart. Given our own existence, we can perhaps rule out theories which give very low probability of emergence of life in the whole universe, but the probability of emergence of life on a given habitable planet may still be incredibly low (if some molecules have to randomly combine in a certain specific way).
3Galap6yI don't agree that metals and heavy elements are necessary for industry and spaceships: you can do quite a lot with light elements, particularly carbon (for example plastics, carbon fiber, etc.). Also, biology makes all of its structure through lighter elements. That being said, I think you're very much on the money with the general idea: I also thought something similar while reading the artifcle (that the filters are likely multivariate and interdependent), but not in as well thought out a way.
0AnthonyC5yWe can do quite a lot with light elements now, after we spent millennia figuring out metals. We still use a lot of metal equipment and catalysts in the manufacturing of polymers and carbon fiber. I'm sure there are processes for making them without metals, but getting civilization going in the first place would be much harder without elements heavier than iron.
1skeptical_lurker6y(gorillas have theory of mind)[ [] ] Although, maybe an ancestor of theirs was a omnivore?

Agree. the road from creation of life to creation of any nervous system at all is an extremely long and fraught one.

Life on our planet has a very specific chemistry. It's possible that almost all possible chemistries limit complexity more than ours - leading to many planets of very simple organisms. Very large number of phyla on earth reach evolutionary dead ends both archae and bacteria are stuck as single cellular organisms, (or very simple aggregrates) - Plants cannot develop movement because of their cell walls, while insects cannot grow bigger because their lungs and exoskeletons do not scale upwards.

Genetics is an entire optimization layer underlying our own, neural one. I think the fact that it had to throw up an entire new, viable optimization layer represents a filter.

7twanvl6yThis is another good explanation instead of / in addition to the Great Filter. It could be that there are many local optima to life, that are hard to escape. And that intelligence requires an unlikely local optimum. This functions like an early Great Filter, but in addition, failing this filter (by going to a bad local optimum) might make it impossible to start over. For example, you could imagine that it were possible to evolve a gray goo like organism which eats everything else, but which is very robust to mutations, so it doesn't evolve further.
4zslastman6yYes. And this is what has happened to most branches of the tree of life. E.g. Archae Bacteria, the various Protists. Only very basic multicellularity occurs in most kingdoms.
2Houshalter6yCould it be that different niches of life don't independently evolve because those niches are already being filled? Can we say with confidence that if all animals died, something like animals wouldn't eventually evolve again? Or any order of life.
1zslastman6yThat's a good point. I guess not. My intuition is that a lot of organisms have evolved simple multicellularity, and so would probably be doing better as unified multicellular organisms, but it's possible, as you say, that they haven't gotten to that point for lack of the niche. I don't know enough about the topic to say.

One theory gaining support recently is that the transition from prokaryote to eukaryote was damned hard, so that seems like a decent candidate given our limited knowledge today.

If the current model - merger of multiple prokaryotes - is correct, then the linked article (which says "And in more than 3 billion years of existence, it happened exactly once.") is incorrect. Nuclei, mitochondria, and cholorplasts represent 3 distinct merger events here on Earth. Actually, the article even mentions nuclei, mitochondria, and chloroplasts all being likely endosymbionts, then goes and repeats the claim of uniqueness.

In any case, if it can happen 3 times on one planet, it probably isn't dramatically unlikely, especially since at least one of those three events (chloroplasts) is strictly unnecessary for intelligence (in that no known intelligent species possesses them).

2someonewrongonthenet6yWait, nuclei? Link? Where's the host's DNA, then?
3Nornagest6yThat's a version of the "chimeric theory", one of a few for the origin of eukaryotic organization: see Wikipedia's article []. The DNA of the host cell would have migrated into the encapsulated bacterium or archaeon, through processes that I'll admit I'm a bit fuzzy on. (Wikipedia links several papers in support of this theory; the only un-paywalled one I could find, however, is Margulis et al. 2000 [].)
2someonewrongonthenet6yHuh. I've skimmed this a few times and it's pretty hard to understand... so they are saying that the nucleus ancestor was a fast swimming oxygen avoider, and it basically chose to avoid oxygen by hiding inside another cell like a hermit crab - and in exchange, pushing the "shell" cell around...and eventually fusing genomes with it?
1AnthonyC1moLink [,1a%3B%20%5B15%5D).&text=Models%20describing%20the%20origin%20of%20the%20nucleus%20in%20eukaryotes.] to a review article I don't know the answer to your question other than "they merged more fully than the genomes of other endosymbionts," and in any case endosymbiosis is only one proposed explanation for the origin of the nucleus.
2lukeprog6yI wasn't proposing the merger of multiple prokaryotes as a candidate for Great Filter, I was proposing the transition from prokaryote to eukaryote as a candidate for Great Filter.
1AnthonyC1moFair enough. I was reaching too far in assuming endosymbiotic events were the limiting factor in that transition.

If the Machiavellian Intelligence Hypothesis is the correct explanation for the runaway explosion of human intellect - that we got smarter in order to outcompete each other for status, not in order to survive - then solitary species like the octopus would simply never experience the selection pressure needed to push them up to human level. Dolphins, in contrast, are a social animal, and maybe dolphins would be susceptible to intra-species selection for intelligence.

However, dolphins would hit a different filter, with their unfortunate body plan, lacking any type of fine manipulator limb whatsoever, making it infeasible to build complex tools.

8Azathoth1236yOctopuses also have the feature that they die after mating (it's unclear why this evolved). This makes it impossible for them to develop a culture that they can pass on to their children.
4CCC6yNot necessarily. A culture that include the concept of a "raiser" - an octopus with the job of raising the babies, and passing the culture on to them, without mating at all - can avoid that issue. The "raiser" would also improve his average genetic fitness if he is a sibling of one of the parents, since the children would then all have approximately one-quarter of his genes. If it's not enough to kill off the species, evolution generally won't drop the feature.
6Azathoth1236yThis is a lot less motivation than for parents. Well, for starter if you don't die after mating you might be able to mate again. According to my source, which is a blog comment that doesn't site its sources, the death is a form of controlled cell-death and scientists have been able to remove the gene responsible and the resulting octopuses (or squid) can mate again later.
2CCC6yThat is true. This might - purely hypothetically - lead to a massive boom in octopus population, causing the octopi to eat everything edible, causing mass starvation. Or it might be that octopi lack any form of parental instinct; that, six months after the babies are born, the parents see them as "food", severely reducing the probability of there being another generation. (This would even be an advantageous mutation for octopi that die after mating, because it means that a given genetic line will work towards eradicating the children of any other genetic lines, giving their children less competition...) Either way, until an octopus in the wild develops the "does-not-die-after-mating" mutation on its own (or possibly escapes from the lab, if what those scientists did is inheritable), evolution will do nothing to get rid of it. And once it does turn up in the wild - well, all else being equal, I'd expect that mutation would supplant the previous, "die-after-mating" model eventually... after a few thousand years or so. Evolution is not, by any means, a completed process.

This might - purely hypothetically - lead to a massive boom in octopus population, causing the octopi to eat everything edible, causing mass starvation.

This relies on group selection to work.

1Capla6yWhy was this down-voted?
1CCC6yI'm not quite sure; I think it might be because of the claim that one of the possibilities I'd suggested required invoking group selection to work (a claim which I'm not sure is valid, but I'm also not sure enough of my grounds to argue against). That's the only reason I can think of...
1Eugene6yFor a species driven entirely by instinct, yes. But given a species that is able to reason, wouldn't a "raiser" who is given a whole group to raise be more efficient than parents? The benefit of a small minority of tribe members passing down their culture would certainly outweigh those few members also having children.
3Decius6yIn addition, cultural memes can evolve and be passed down completely independently of genes. It doesn't matter to the cultural memes if they propagate using genetically unfit people; celibate monks were a culture where celibate monkhood was a real thing.
2RichardKennaway6yFrom the genes' point of view, the soma is just a vehicle for transporting the genes through time. With each generation, the genes shed the soma like people change their car. If the parent is unnecessary for the survival of the children, the genes in the children may be better off for not having the parent around to compete for food.
1Azathoth1236ySee my comment about group selection below.
1RichardKennaway6yThis is competition between the parents and their own offspring. No group selection.
1felzix6yOrson Scott Card uses this dynamic in the later Ender's Game books.
-1hairyfigment6yThe world-building in the first Ender's Game book can be made roughly consistent if we assume that all the adults have turned their decision-making over to a computer program (which does not eat the solar system Because Magic). But the later books have no standard or intended models.
3Vladimir_Nesov6yDo you expect animals with human-like intelligence and dolphin-like bodies will fail to develop technological civilization? As a first approximation, I expect a community of modern human engineers (with basic technical background, but no specific knowledge) in dolphin bodies can manage to do that eventually, if they form a society conductive to long-term pursuit of the project. It's less clear if at human level this happens spontaneously, since it did take 200,000 years for humans with hands to get to technological civilization, and an additional difficulty could make it millions of years if intelligence is kept fixed. (Assuming that machiavellian intelligence pressure can run further than it did with humans, machiavellian dolphins could at some point become even smarter than humans, which can be used to overcome the no-hands difficulty more effectively than human-level dolphins could. Alternatively, human-level dolphins can learn of selective breeding and create smarter dolphins irrespective of whether smarter dolphins would arise on their own.)
6Jan_Rzymkowski6yThere's also an important difference in their environment. Underwater (oceans, seas, lagoons) seems much more poor. There are no trees underwater to climb on, branches or sticks of which could be used for tools, you can't use gravity to devise traps, there's no fire, much simpler geology, lithe prospects for farming, etc.

I wonder - if an underwater civilisation were to arise, would they consider an open-air civilisation impossible?

"You're stuck crawling around in a mere two dimensions, unless you put a lot of evolutionary effort into wings, but then you have terrible weight limits on the size of the brain; you can't assign land to kelp farms and then live in the area above it, so total population is severely limited; and every couple of centuries or so a tsunami will come and wipe out anything built along the coast..."

It's hard to evaluate for the same reason it's hard to evaluate whether off-world life could be non-carbon/water-based (maybe we just don't have the imagination), but I think that excluding humans, land-based 'civilization' would still look superior on the merits of what animals and other creatures have done. If we look at compilations of tool use like land life dominates.

Complex sea life mostly consists of octopuses and cetaceans; the former seem to only use rudimentary tools for shelter, while the latter do 'bubble netting' (interesting but not a step towards anything), nose protection with sponges (proto-clothing?), and shells as scoops. Otters hammer open sea urchins with rocks, similar to some fishes. Further, they're cut off from sea sources of metal and minerals like deep-sea vents - dolphins can't go that deep.

In contrast, land life has tool use spread over all sorts of creatures from insects to birds. They benefit from sharp unworn stones (smashing, throwing), abundant sticks and thorns (which can be used in all sorts of ways - picking up termites, jabbing for fish, measuring water depth, impaling & storing prey like th... (read more)

9CCC6yYou make a very compelling argument, and on balance I think that you are probably correct in your conclusions. Part of it may be because, for a land animal, the ground is always there. There's always a strong probability of a rock at your feet to pick up. For sea creatures, it's possible (in theory) to wander around for months without seeing another solid object. So, land animals have less space to move about in, but have an easier time finding simple tools. This, of course, relies on the idea that tools - unliving lumps of matter used for a purpose - are a necessary component of a civilisation. It goes without saying that tools are a necessary component of our civilisation; but are they a necessary component of all possible civilisations? The theoretical underwater civilisation has one thing in great abundance - space. The oceans cover three-quarters of our planet, and sea creatures can move up and down easily enough. Is there any way that that space can be used, as a foundation for some form of aquatic civilisation? Thinking about bubble netting - it should be possible for dolphins to practice a form of agriculture, herding and taming schools of edible fish, much like shepherds. (I believe ants do something similar with aphids, and I'm pretty sure a dolphin is more intelligent than an ant). Once one has shepherds, one can easily move towards the idea of breeding fish for a purpose - breeding big fish with big fish to get bigger fish, for example. Or breeding tasty with tasty to get tastier. There's certainly space in the oceans for the dolphins to create a lot of fish farms... and then for these fish farms to swap and interbreed particularly interesting lines. I'm not quite sure how to believably get beyond a basic agricultural/nomadic existence, though. (Unless perhaps the dolphins start breeding intelligent octopi with intelligent octopi to get more intelligent octopi or something along those lines).
5PeterisP6yDolphins are able to herd schools of fish, cooperating to keep a 'ball' of fish together for a long time while feeding from it. However, taming and sustained breeding is a long way from herding behavior - it requires long term planning for multi-year time periods, and I'm not sure if that has been observed in dolphins.
6Strange76yKelp and fish can be farmed.
5FiftyTwo6yWhy would they want to? A modern dolphin can get basically all the food its needs with minimal effort,so the main competition is intra-species. So for a dolphin society to advance technologically you would require every individual within it to give up their own reprodutive fitness but putting time and energy into the great project with no immediate benefit. For a technological society to develop it isnt enough that with sufficient coordination they could do so, but that it is in their self interest at every step along the way. edit It may also be possible to fall into local maxima and not get out of them even once a species has got a starting level of technology. Consider that humans spent 2.6 million years or so at paleolithic technology levels, and were probably only knocked out of it y sudden environmental change not by a gradual process of improving technology.
5Thomas6yThey don't. They either starve, be killed by predators, humans or by something. They haven't escape this bloody cycle of exponential population grow on one, and mass death on other hand. There is nothing like a "stable population" among dolphins.
4Vladimir_Nesov6yThis is part of a hypothetical intended to explore the issue of technical feasibility of developing technology using only dolphin bodies (underwater, etc.). This hypothetical removes two other most obvious issues in order to focus attention on this one. It removes the issue of developing useful-in-practice understanding of science by assuming that we have modern engineers. It removes the issue of unfavorable incentives by assuming that the incentives are directed towards the project. You can explore other issues in other hypotheticals.
1CCC6yThis group of dolphins might do it as a (long-term) way to better compete with that group of dolphins over there.
3EGI6yHow? You can not have fire (no magnesium, phosphorus and so on do not count, since you do not get them without fire), thus you do not get metals, steam and internal combustion engine. Since you do not get metals, you do not get precision tools, or electricity. You are more or less stuck with sharpened rocks and whale bones as a very poor substitute for wood (if you get them in the first place). I am very curious how you think a human or even smarter than human inteligence might bootstrap an industrial civilisation from there.
9Vladimir_Nesov6yMostly I expect creative surprises [] based on overall impression about the power of engineering. Let's try to do a bit of exploratory engineering [], consider projects that include steps that are clearly suboptimal, but seem like they could do the trick. (A practicing engineer or ten years of planning would improve this dramatically, removing stupid assumptions and finding better alternatives; a hundred thousand years of actually working on the subprojects will do even better.) Initially, power can be provided by pulling strong vines (some kind of seaweed will probably work) attached together. It should be possible to farm trees somewhere on the shoreline, if you don't mind waiting a few decades (not sure if there are any useful underwater plants, but there could be). A saw could be made of something like a shark jaw with vines attached to the sides, so that it can be dragged back and forth. This could be used to make wooden supporting structures that help with improving control of what kind of change is inflicted on the material by a saw. Eventually, incremental improvements in control and precision of saws would allow getting to something functionally similar to sawmills, bonecraft and woodcraft tools. These enable screws, joints, jars and all kinds of basic mechanical components, which can be used in the construction of tools for controlling things on surfaces of rafts, so that in principle it becomes possible to do anything there given enough woodcrafting and bonecrafting work. At this point we also probably have fire and can use tides to power simple machinery, so that it's practical to create bigger controlled environments and study chemistry and materials. And we get concrete/cement to create watertight buildings and possibly canals with locks for land access. Something like ironsand [] or ores from surface explora
7EGI6yI think the basic problem here is that I have to proove a negative, which is, as we all know, impossible. Thus I am pretty much reduced to debating your suggestions. This will sound quite nitpicky but is not meant as an offense, but to demonstrate, where the difficulties would be: Power to what? Whatever it is it has to be build without hands !!! and with very basic tools. No Seeweed would not work, because there is no evolutionary pressure on aquatic plants to build the strong supportive structures we use from terrestrial plants. No, trees do not grow in salty environment (except mangroves). How does a dolphin plant, and harvest mangroves without hands and without an axe or a saw (see below). No it can not: Shark teeth would break quickly and even if they would not, they do not have the correct form to saw wood. Humans allmost exclusively used axes and knives for woodcrafting before the advent of advanced metallurgy. And you do not get wines. I think you severely underestimate just how helpless a dolphin would be on such a raft or are we talking remote operation? Without metall? Without precision tools? (I mean real 19th century precision tools - lathe, milling cutter and so on, not stone age "precision tools") To get land access and do uesful work there (gather wood, create fire, smelt metal ect.) a dolphin would imho need something like a powered exoskeleton controlled perhaps by fin movement or better by DNI. Modern humanity might perhaps be able to build something to enable a dolphin to work on land, but not a medival or a stone age human civilisation and certainly not a stone age civilisation without hands. I hope I have brought across which kind of difficulties I think would prevent your dolphin engineers from ever getting anywhere. If you disagree on a certain point I am willing to discuss it in greater detail
2Vladimir_Nesov6yIt's not impossible. [] Significant evidence of the negative will be obtained if performing a thorough investigation (which would be expected to solve the problem if it can be solved) fails to solve the problem. Applying this to flaws in particular steps, the useful goal is to show that something can't be done (that we won't find an alternative solution), not just that something won't work if done in a particular way. For constructing a plan, I have another idea. Start with the simpler problem of developing technology as dolphins with hands. This hypothetical isolates the problem of dealing with underwater environment, from the problem of dealing with absence of hands. Let's suppose that it's possible to solve this simpler problem. Then, I'm not sure that when we have a particular tiny operation that could be performed with hands (a step in the process of developing technology by dolphins with hands, such as smashing something with something else, or tying a knot), it's impossible to reproduce it without hands (much more laborously, slowly, using more people). Can you come up with a particular example of a very simple action that can be performed with hands (underwater, etc.), which doesn't look like it can be reduced to working without hands?
2private_messaging6yGo to a prehistoric museum, even the simplest items you see (stones tied to sticks very securely for example) are not at all easy to do with your hands and are going to be so hard to do with just the snouts that they could be deemed impossible (and would be properly impossible if you consider e.g. the rate of decay of your materials combined with the minimum time to build it, or the like. Sufficient difficulty is impossibility). It's not that you can't tie some knot, it's that you can't do so reliably and with high precision in the spot where you need it. I think we can all agree that the difficulty gap is absolutely immense. Perhaps dolphin bodies, with no magical knowledge, could do it, but at an intelligence level that is utterly, immensely superhuman.
2EGI6yYou could allways argue that we are both not creative / inteligent enough to find a solution and that this is not indicative that a whole society would not find a solution. And this argument may well be correct. What does that even mean? A dolphin body with functional human arms and a human brain attached and the necessary modifications to make that work? Well now you have got more or less a meremaid with very substantial terrestrial capabilities (well exeeding those of a seal; watch this to get an impression of what I mean [] ). A group of creatures like that with general knowledge of science might well make it. Now imagine this creature as strictly waterbound and I think even in this much simpeler problem we can identify a major showstopper: Iron smelting. Imagine this meremaid civilsation with propper hands, and flintstone tools (Can flintstone be found in the oceans? I don't know) and modern scientific knowledge trying to light a fire. They gather mangrooves using their flint axes, build a raft and throw some wood atop to dry. What now? They cannot board the raft to strike or drill fire so they might try to bulid a mirror to use sunlight. Humans did not do that, but they did not know science, so granted. How do they build it without glass or metal? I don't know, but let's say they manage. So now they have fire, not controlled fire, but a bonfire atop a wooden raft. But they don't need a bonfire they need something like a bloomery and then they need to do some very serious smithing only to build something like a very crude excavator arm to do very basic manipulations in a terrestrial environment. And you cannot do smithing under water. Can you imagine a way a group of quadruplegics ( imho a good aproximation of a stranded dolphin with a human brain - except that their skin does not dry out - ) could fell a tree with stone tools? And delimb it? And bring it to the construction site? And erect it as a pillar?
2CCC6yI don't know about quadruplegics, but I can imagine a way that a group of dolphins might be able to fell a tree using only stone tools and a bit of seaweed. First, they would need a suitable tree. One that grows near the water (probably near a river they can swim up) where it's easy enough to get to (and other dolphins can stay in the river and splash the woodcutter to prevent his skin from drying out). Then, they need a stone axehead. This can be made, fairly laboriously, using only stone; chipping away until is is the right shape and sharp enough. The dolphins then elect one of their number to be the woodcutter, and use the kelp to tie the axehead to his tail, at a carefully chosen angle. (This part can be done underwater, where the dolphin(s) tying the knots can swim around at all angles to get the kelp in position; another dolphin would probably need to hold the axehead in position while this is going on). A dolphin's tail can certainly swing back and forth (or, up and down) with some force, as this motion is used when swimming. So the woodcutter would then need to climb out of the water, turn on his side, and strike the tree repeatedly with the axehead... If he has a better idea of what he's doing than I would, he may even be able to arrange for the tree to fall into the river, at which point transportation is comparatively easily handled.
2Vladimir_Nesov6yGiven an expectation of how hard it is to solve the problem if it can be solved, inability to solve it with given effort produces corresponding evidence of impossibility of solving the problem. Not responding to inability to solve the problem amounts to actually expecting the problem to be very hard. If I don't expect that, I would be wrong in suggesting that inability to solve the problem is not evidence for impossibility of solving it. Another framing is to generalize "inability to solve the problem" upon the conclusion of the project, to a situation where the expectation that the problem can be solved eventually is reduced. Correspondingly, generalize "ability to solve the problem" with expectation having gone up upon the project's conclusion. This way, it's clear by conservation of expected evidence [] that you can't expect that the estimate for the probability that the problem is solvable will go in a particular direction upon the conclusion of the project. Either the expectation will go up (and so the project produces evidence of the possibility of eventually solving the problem), or else it must go down (and so you gain that elusive evidence of the negative). Sure, depending on what you are thinking about as the reference procedure of, say, chopping down a tree when using hands. Dolphins with hands won't just be swinging an axe on the surface, as they would first need to solve the problem of being able to move around, so I'm responding to the analogy with humans who have to do the task without hands, but do have legs. For dolphins, we would need to start with the reference procedure where it's clear how dolphins with hands can do something. To chop down a tree, you need to strike it repeatedly with an axe (this is what I assume you meant). To strike it repeatedly, you need to be able to strike it once. It's such actions as striking a tree with an axe once that I meant as something that I expec
2EGI6yAgreed No they are not. They are much less waterbound than seals (watch the video), because they can move around on their hands and use their hands to cover themselves with seaweeds or somesuch to protect against drying / sun. I fully agree with you that such creatures are can bootstrap a civilisation especially if they have scientific knowledge. Where I disagree is the point where an unmodified dolphin or a strictly waterbound (arbitrarily defined as cannot leave the water for more than 5 seconds) "dolphin with hands" gets anything done on the surface without having significant technology to start with (arbitrarily defined as anything humans could not build 40000 years ago). They would run into the problem that they have to build complex contraptions to perform simple tasks (felling a tree) without being able to build those complex contraptions without the help of even more complex contraptions (You cannot build what you described in the above quote without having wood and being able to work with it - and do that in a terrestrial environment, where you can not do anything in the first place, because you can not move.).
1Lalartu6yIt is not a major problem at all. Given that creatures have hands and can keep them out of water, they can build a bloomery inside a diving bell.
3Azathoth1236yChicken and egg problem. What are you building the diving bell out of?
2CellBioGuy6yMore to the point, why would they want to? What would drive them to do so?
1Lalartu6yFor example, out of animal skins. This construction is supported by internal pressure, it does not need strength. Want exactly what? If "smelt metal", then probably the same as humans, accidentally placing copper or tin ore in furnace. If "having underwater furnace" - it is easier to operate than one placed on raft. If "why use fire at all" - to make watertight pottery.
2Houshalter6yThe dolphins could practice eugenics and evolve hands or lungs. If they find that unethical, they could selectively breed other organisms for various tasks. The same way us humans bootstrapped our civilization. We didn't start farming and building cities overnight, we had to selectively breed productive crops first. Then useful work animals like horses.
1private_messaging6yBut how you imagine that would work? How will a longer timespan help? Let's picture that we literally took 10 000 top human engineers and scientists, with all our human knowledge, into dolphin bodies, on another planet with no human artefacts. So, our dolphin people now need to somehow develop a way of writing down their knowledge underwater, which they can only do very laboriously because they haven't got hands. They can write very large letters with immense energy expenditure per letter. They can barely store any knowledge. They also got short lifespan and sharks to worry about. And on the tools side, you need tools that are good enough so you can use them to make better tools. That generally requires ability to harden things - make something while it's soft, let it harden, use something softer to crack apart something harder. And to get that started, you need hands, because without hands you can only make the kind of tools that doesn't help you make better tools. If you can't make an improvement in any single generation, you can't make any improvement in a thousand generations either. Meanwhile, a planet populated with those same scientists and engineers in human bodies - hell, dog bodies, cat bodies, elephant bodies - would've had it all sorted out in no time. They'd have steel, electricity, running water, radio, and so on, in less than a generation - hell even 10 people can do that. (assuming they all cooperate). The gap due to the body shape and environment appears utterly immense. The only hope would be that dophins would evolve much greater than human intelligence and come up with something that we can't come up with (e.g. mind controlling some animal with hands). edit: That is not to say a small number of top scientists and engineers would single handedly create industrial manufacturing, but that is to say they would re-create pre-industrial village level technology and then hand-make many important bits of 20th century technology. You can take a 1
4Lumifer6yThat's a bad start. The issue is not whether intelligent dolphins will be able to replicate human civilization, the issue is whether they might be able to develop their own -- one which will look very different from human and which, I suspect, would be largely beyond our imagination at the moment.
1private_messaging6yThe point of the example is to provoke a concrete discussion. Appeals to unimaginable are not very useful. The underwater environment doesn't seem as conductive to technological visible-from-a-distance civilization, in any case. Dramatically different civilizations may not go into space, and if we are discussing civilizations whose apparent absence in the sky is suspicious, those recreate a huge chunk of our own civilization. edit: let's put it this way. The only data point we got on things such as civilization not becoming stagnant, or civilization becoming visible, is our own. The further we go from there the less reason we have to expect those to occur.
0Lumifer6yI see absolutely no reason for that to be so. Generalizing from the sample of one is foolhardy.
0private_messaging6yGeneralizing from the sample of one is where you get the idea that we'll see them from. edit: let's just agree that the assumption that aliens would be visible has uncertainties, that are much larger for some really really alien unimaginable aliens.
3Lalartu6yTaken literally, no. There will not be any civilization above hunter-gatherers without domesticated plants and animals, and that cannot be done in one generation. Remember that ox and wheat also are human artefacts. Well, realistically (in human variant) most of them will be dead very soon, survivors become nomadic hunters.
1private_messaging6yHunter gatherers had a lot of free time, though. And as for the most of them getting dead very soon... I dunno, wildlife survival is not really that hard in general. We only have wildlife left in the regions where it's very hard for humans to live, so if you drop people into the remaining regions of wilderness, they don't fare very well. And we didn't start on the wheat cultivation with the grand plan of going to the moon, we did that because the wheat as it was naturally gave huge and immediate benefits. I don't think you'd end up with a culture resembling any culture that existed in history. You have those smartest engineers and scientists, who already know how to make bows, steel, glass, firearms, electrical generators, and so on, and once settled in, they have a lot of free time (because there's a ton of wildlife - buffalo herds, passenger pigeons, all that other easy to kill stuff that's extinct - which will take many generations to deplete. They're not in the modern day wilderness in the region where people can barely survive and almost all the food is extinct. They're the new predator).
1Lalartu6yFirst, hunting with stone age weapons is far fom easy. Second, most engineers and scientists are not hunters, noone of them know how to hunt with spear and almost noone with bow. Third, they have no food supplies and so no time to learn. They will survive olny in very favourable conditions, like on tropical island with plenty of shellfish and tortoises (I think most people can hunt those).
1private_messaging6yI were thinking of my experience in Russia where engineers, mathematicians, and physicists absolutely loved going out on various nature trips (Didn't really think of Sheldon and US tv shows). Of course, not everyone did, but we're dropping a huge number of people, and those who know can teach those who don't. Healthy person can go for 2 months without food. Let's say that they spawn on 1kmx1km zone in a grid with 10m spacing, in the temperate climate in the late spring, clothed in earliest stone age clothing (for same reason why we don't spawn dolphins into a desert, we don't spawn people into the Arctic).
3juked076yThis strikes me as very human centric. Why should another species' hypothetical ascension look so much like the one we happened to observe in humans?
1private_messaging6yIf it looks too different, we won't see them in space, though. Our own intelligence is at the level where it's just barely sufficient to build a civilization when you got hands, fire, and so on. Note that orcas have much larger brains than humans, and had those larger brains for quite a long time, yet we're where we are, and they're where they are.
3Stuart_Armstrong6yLikely because the first beings that could do that, did do that - no need to wait for the evolution of higher intelligence (so, in particular, this doesn't show that higher intelligence couldn't evolve).
1private_messaging6yYeah, that's precisely my point. If there's more obstacles, intelligence has to go further before the technological civilization. We did get higher intelligence but only by other means (e.g. having paper and pencil helps, better nutrition gives higher IQ, and so on).
2Mizue6yThe Wikipedia article listing number of neurons in the cerebral cortex [] shows humans as significantly higher than whales, even though raw brain size may look better for whales. Wikipedia also describes an encephalization quotient [] which takes account of the fact that the brain is used for bodily functions, and on which whales don't score as highly as they may seem to from brain size.
1private_messaging6yYeah, that's quite interesting. Raises the question though, why do they not have more neurons? They do have larger glia to neuron ratios, it's not like everything's simply bigger. Perhaps aquatic environment simply doesn't reward intelligence that much. Well, the bodily functions are the same but occurring at a lower rate, for a larger mammal. Most of whale's body is fat, anyhow, which doesn't need to be controlled by brain, and it's not generally the case that people drop many IQ points when they become overweight. Nor are smaller people with same sized heads more intelligent. edit: on the other hand, EQ may be a (very crude) measure of how well brain tissue pays off for an animal. If you have high quality brain tissue and you're in a complex environment, at the equilibrium between costs and benefits you would haul around more brain mass per body mass. With the obvious caveat that this tradeoff is very different between land animals, flying animals, and aquatic animals.
1[anonymous]6yWomen are in average approximately as intelligent as men (though it depends on how you weigh visual intelligence vs verbal intelligence, and anyway their variance is smaller) even though they have smaller heads.
1private_messaging6yBut is it because of the smaller body sizes using less brain for the bodily functions? I don't think so. edit: I frankly don't get the point with EQ. If we had to make a computer control for bodily functions (e.g. to grow ethical meat), we could do with a weaker cpu for larger animals because they work slower. It just doesn't make sense that body size would be using up brain to control it, irrespective of the composition of that body.
2Lalartu6yYou greatly underestimate population size nesessary for civilization.
1private_messaging6y10 people, of course, can't rebuild the whole civilization, but 10 top scientists and engineers with relevant expertise, given access to the natural resources, can make iron, steel, copper, tooling, build an electric generator, and so on [assuming they don't get eaten by wildlife early on]. Of course, when they die out, it's gone with them - the heavily inbred future generations aren't going to be able to continue that, and probably won't even survive.
4Lalartu6yNo they cant. For example to make copper you need copper mine workers, smeltery workers, woodcutters, charcoal burners, wagon drivers to transport wood, ore and coal, carpenters to make wagons, builders to build mine and smeltery and farmers to feed them. That is impossible for population less then few thousands at least. Industry nesessary to make a generator requires population in millions.
1private_messaging6yTo make copper, you need copper ore and charcoal and a fire and bellows out of animal hide. Those things weren't produced in a modern industrial manner until something known as "industrial revolution". You had a little town, it had a blacksmith, and the blacksmith could smelt his own iron (and copper, if he has the ore, as copper smelting is pretty easy). You'd be surprised how much technology existed entirely locally within a small village.
3Lumifer6yActually, to make copper tools all you need is copper nuggets (which aren't all that rare []) and a couple of rocks. Humans made tools out of meteorite iron before they developed metallurgy.
4private_messaging6yHeh, yeah. But when you don't have transportation and it's just 10 people it may be difficult to find such things without a metal detector... I was just recalling one time I made a little bit of copper from low grade malachite, using a torch. It is really easily reduced from the ore. More easily than iron.
1AshwinV6yNot necessarily. For reasons that are completely intuitive, I imagine our top 10 000 scientist et al. would be able to fashion tools, that could be used very effectively. You make the assumption (albeit loosely) that progress happens along a straight pre-determined path, where things happen in a specific sequence, much like they did in human history. This is far from so. We are talking about a different planet out here. I'm not suggesting that different laws of physics will be applicable. But the odds are that the oceanography, will be vastly different, with all sorts of different materials that would be available. There's no guarantee that this planet (from here on called "Dolphin Alpha") that steel would even exist or the necessary elements are present on the planet. On the other hand, you could possibly have all manner of other material. Perhaps, under water civilization would have a very different set of social rules. HEAVY USE OF HYPERBOLE FOLLOWS Given that these are the most brilliant 10 000 scientists that are present on the planet, I'd expect a sizeable number of them to know morse code, which can then be replicated in dolphin sounds (am no expert, but you'd need only two distinguishable sounds if I've got the concept correct). A good number more would be experts in Game theory. The homo sapiens dolphinus (again no expert, but this sounds authentic enough to me! How about we call them HSD for short?) that happen to know both morse code and be well versed in the more salient features of Game Theory, would probably rise to political power within the ranks of the HSD, and since these arent politicians who are in it for material gain (that part comes much later in the advent of a civilisation) and are truly interested in the welfare of the civilisation, would probably find ways to domesticate (or if you prefer the harsher equivalent "enslave"), all sorts of smaller creatures that could work for them!! For the sake of simplicity, if we assume that mari
1private_messaging6yI have your 'domesticate other animals' listed in a footnote. Would take a long time and getting the domesticated animals to the point where they're a replacement for your hands... that's on par with a breeding program to regrow your own hands. The time during which you can make environment easy enough that your intelligence de-evolves.
1CCC6yThey don't need to write it down, they just need to store it. A certain amount of knowledge can be "stored" as oral tradition; alternatively, a lot more knowledge can be stored as (say) a pattern of rocks, carefully gathered and moved into position, in an area that can be easily visited. Some knowledge will almost certainly be lost in the first few generations, despite that.
2private_messaging6yOral traditions decay quickly, though. And rock placement is an example of far higher effort per letter. The point is, they find it much harder to retain knowledge. If the rate of loss is greater than the rate of creation, there's no progress at all. And even after you're storing the knowledge, you're still entirely out of luck on tools. Even if they have waterproof'd encyclopaedia handed to them, they still have this make tools to make tools to make tools cycle that they can't even bootstrap. The point is, putting that side to side with humans in some land animal bodies, you have on one hand a bunch of dolphin people who lost pretty much everything in a few generations, save for a few myths that are of no practical use, and on the other hand you have those land people with electricity, radio, and everything, a good chunk of 20th century tech.
1CCC6yWhy on earth would they lose everything? Yes, there would be some significant losses in the first few generations. But if you teleport the top 10 000 scientist and engineers onto an alien world with no human artifacts and leave them in human bodies, there will also be some significant losses in the first few generations. Once data storage technology is able to keep up with the volume of knowledge retained, then the losses will stop, and knowledge will slowly start to be regained. If they're sensible, they'll realise that they can't retain everything, and put some effort into retaining that which is important. Why not? Hydraulic cement [] will harden underwater, and can be carefully pressed and moulded into shape. And while I have no idea how dolphins can get to that point, apparently even underwater welding [] is possible.
3private_messaging6y'cause nothing they know is particularly useful for future generations. You just get distorted myths, and it doesn't take much distortion until technical knowledge becomes entirely non trustworthy and thus worthless. But can you make hydraulic cement underwater? I was under the impression that you needed fire to make it.
1CCC6yKnowing how to make hydraulic cement isn't useful? I am quite certain that the 10 000 top engineers and scientists know quite a few things that would be very useful for future generations. Since I am not in that number, and since I am only one person, I do not know what those things would be, but I estimate a high probability that they exist. I'm not sure. The Wikipedia article mentions that the ancient Romans used a mixture of volcanic ash and crushed lime, and you certainly do get underwater volcanoes, so the ash should be available... there are probably industrial processes now, but just mixing volcanic ash with the right sort of mud and getting something that hardens if you leave it for a day or two sounds usable underwater to me.
4EGI6yNo, the ash would react with water immeadetly and thus be useless and you need burned lime (CaO or (CaOH)2), not limestone (CaCO3)
1CCC6yAh, thank you. I wasn't sure about that.
2private_messaging6yBut it's not enough to convey the formulas, you need also to convey the context. And you need to do so reliably, without later generations adding in nonsense of their own. When the knowledge is in use, it's naturally checked against reality and protected against decay. re: cement, my understanding is that you still need to fire components to make hydraulic cement, and underwater ash won't work.
1CCC6yWhich means that they will best remember things that they can immediately put to use, yes. Such as how to breed fish for desired characteristics, maybe? Or how to create some basic tools.
1private_messaging6yBut what those tools may be, besides the tools real dolphins already invented? And breeding fish requires some sort of enclosure, ability to manipulate individual fish, etc. It's not even clear there's anything to gain from breeding fish if you don't do some underwater agriculture for fish food (and thus need fish very different from available species to make full use of that). Perhaps the reasons dolphin's large brains are not particularly optimized (comparing to ours) in terms of neural density, despite ample time at their brain volume, is that they already do pretty much everything that a greater intellect would do. On the ground and with the hands, when our intelligence was the same as of dolphins, we had a lot of complex and useful things we could have been doing if we were a little smarter, and that's how we evolved our intelligence (and conversely, how they didn't evolve much further).

Note that AI is certainly not a great filter: an AI would likely expand through the universe itself

What makes you confident that there's not high probability of there being an AI somewhere outside our light cone, but shortly after an AI (or any other highly expansionist extraterrestrial) enters our light cone there are no longer conscious observers, so the vast majority of human consciousness-seconds are spent observing that there's no visitors? Even if it's vanishingly unlikely that no destructive intelligence explosion occurred in a randomly selected ... (read more)

Then the universe we observe should be much younger, because most evolutionarily-arising life will exist on worlds that don't have a nearby AI neighbor. Our telescopes can see older galaxies than this one, and we expect those to contain much older planets with all the heavy elements. On your hypothesis, most observers should not utter that sentence in conversations like this one.

3RussellThor6yThis person claims that all AI will rationally kill themselves and that the great filter would be after AI. [] (I havn't got the paper but even if this is correct, to me it still would not explain the filter fully because a civilization could make a simple interstellar Replicator e.g. light sail propelled asteroid mining robot and let it lose before going AI and we see no evidence of these) Also what about the Planetarium/galactic zoo/enforced noninterference possibility. Say that 99% of the time AI will take over the light cone destructively, but 1% of the time the AI will desire to watch and catalog intelligence arising then darkly wipe it out when it gets annoying and tries to colonize other stars and hence stuff up other experiments. Or more nicely it could welcome us to the galaxy and stop us from wiping out other civilizations etc. For us it would mean that we got lucky with a 1% chance say 1 billion years ago when the first intelligent civilization arose, spread through the galaxy/light cone and made the watching/enforcing AI. (or made the watching AI then fought itself etc) There could have been ~1 million space-faring civilizations in the galaxy since and we are nothing special at all, on an average star in the middle age of the universe. In the case the filter is sort of ahead of us because we cannot expand and colonize - the much more advanced AI would stop us. Either way if we make a simple replicator and have it successfully reach another solar system (with possibly habitable planets) then that would seem to demonstrate that the filter is behind us. We would have then done something that we can be sure noone else in the galaxy has done before as I have said we see no evidence of such replicators. I am talking about one that could not land on planets, just rea
4chaosmage6yExcellent! So, wouldn't that mean that the best way to eliminate x-risk would be to do exactly that? It is counterintuitive, because "eliminating x-risk" implies some activity, some fixing of something. But we eliminated the risk of devastating asteroid impact not by nuking any dangerous ones, but by mapping all of them and concluding the risk didn't exist. As it happens, that was also much cheaper than any asteroid deflection could have been. If sending out an interstellar replicator was proof we're further ahead (i.e. less vulnerable) than anything that could have evolved inside this galaxy since the dawn of time, it seems mightily important to become more certain we can do that (without AI). If some variant of our interstellar replicator was capable of enabling intergalactic travel, that'd raise our expectation of comparative invulnerability because we'd know we've gone past obstacles that nothing inside some fraction of our light cone even outside our galaxy has been able to master. Ideally we'd actually demonstrate that of course, but for the purpose of eliminating (perceived) x-risk, a highly evolved and believable model of how it could be done should go much of the way. Of course we might find out that self-replicating spacecraft [] are a lot harder than they look, but that too would be information that is valuable for the long-term survival of our species. Armstrong and Sandberg [] claim the feasibility of self-replicating spacecraft has been a settled matter since the Freitag design in 1980. But that paper [], while impressively detailed and a great read, glosses over the exact computing abilities such a system would need, does not mention hardening against interstellar radiation, and probably has a bunch of other problems that I'm not qualified to discover. I haven't looked at all
2Stuart_Armstrong6yActually, bacteria, seeds and acorns are our strongest arguments for self-replication, along with the fact that humans can generally copy or co-opt natural processes for our own uses.
2RussellThor6yThanks for the comment. Yes I agree that if we had made such a replicator and set it loose then that would say a lot about the filter. To claim that the filter was still ahead of us in that case you would need to make the more bizarre claim that we would with almost 100% probability seek and destroy the replicators and almost all similar civilizations would do the same, then proceed not to expand again. I am not sure that a highly believable model would go most of the way because there may be a short window between having a model, then AI issues changing things so it isn't built. It seems pretty believable for the case of mankind that there would be a very short time between building such an thing and going full AI, so to be sure you would actually have to build it and let it loose. I am not sure why it isn't given much more attention. Perhaps many people don't believe that AI can be part of the filter e.g. the site Also I expect there would be massive moral opposition to letting such a replicator loose from some people! How dare we disturb the whole galaxy in such an unintelligent way. Thats why I mention the simple one that just rearranges small asteroids. It would not wipe out life as we know it but would prove that we were past the filter as such a thing has not been done in our galaxy. I sure would be interested in seeing it researched. Perhaps someone with more kudos can promote it? Likely a replicator would be a consequence of asteroid mining anyway as the best, cheapest way to get materials from asteroids is if it is all automatic.
2Lumifer6yWhy would that be so, especially in the immediate future?
2RussellThor6yImagine if we had made a replicator, demonstrated that it could make copies of itself, established with as high confidence as we could that it could survive the trip to another star, and had let >100,000 of the things off heading to all sorts of stars in the neighborhood. They would eventually (very soon compared to a billion years) visit every star in the galaxy and that would tell us a lot about the Fermi paradox and great filter. As I said before (discounting planetarium hypothesis) we could have a high degree of confidence that the great filter was then behind us. It couldn't really be the case that thousands of civilizations in our galaxy had done such a thing, then changed their mind and destroyed all the replicators as some civilizations would probably destroy themselves between letting the replicators loose and changing their mind, or not change their mind/not care about the replicators. Therefore we would see evidence of their replicators in our solar system which we don't see. The other way we can be sure the filter is behind us is successfully navigate the Singularity (keeping roughly the same values). That seems obviously MUCH more difficult to have confidence in. If our goal is to make sure the filter is behind us then it is best to do it with a plan we can understand and quantify. Holding off human level AI until the replicators have been let loose seems to be the highest probability way to do that, but no-one has said such a thing before now as far as I am aware.
3Lumifer6yI still see no answer to my question. Where is the outisize value to our species? Not to mention that "very soon compared to a billion years" isn't a particularly interesting time frame.

Another fairly plausible great filter is in the interaction between life and geochemistry- this is a variant on 'central nervous systems are unlikely'.

There is some reason to think that microbial metabolisms are somewhat destabilizing in the history of the planet, at least on very large scales. There is of course the classic example of photosynthesis producing atmospheric oxygen. Can you imagine what would happen if bacteria injected large amounts of free oxygen in to Titan's atmosphere? Given the space of all geochemistry for terrestrial planets in the... (read more)

Interesting, but I would have two more things to add :

  1. Both dolphin and octopus seem to be a "dead-end" for the purpose of technological civilization. The main reason for that, I would say, is that there are water-based, and water-based makes early civilization much harder (tools are harder to make and use underwater, you can't make fire, ...).

  2. Evolution from common predecessor to dolphins and octopus aren't completely independent from our evolution. They are all dependent on Earth being globally stable enough. Gravity strong enough to hold th

... (read more)
2Stuart_Armstrong6yThat is a very valid point. It will be interesting to see the climatic stability of other Earth-like planets in the galaxy...
1Slider6yHave humans broken the "chain of stability"? It also comes to mind that evolving is a kind of unstableness. For example the energy innovation introduced oxygen into the air certainly filtered out a lot of development paths. This wasn't that much due to external circumstances. We didn't survive the cold war of oxygen. Also how long do dolphins and octopusses have time to come up with current human level intelligence until considered "filtered out"? I would recorn they would still have atleast a couple ten million years left. What if the reason we got so far was because we didn't evolve that rapidly and could thus develop more enduring traits ie we were boring? A planet that evolves to from one chemistry to another might do a lot of work on keeping the basics of kinetics going but not really getting deep in any branch or spend time adapting to circumstances that come about in a unique way that won't be repeated. That migth up the level of danger from AI. The AI might do more damage than simple extinction of humans it can to some extent try to dial the clock back on evolution. If that kind of "negative progress" is possible giving arbitrary time won't force an inevitable progress state. Anyone know any basis to believe that non-progressive or anti-progressive evolution could overshadow progressive evolution?
3Nornagest6yWe don't know much about the evolutionary history of octopuses -- they're practically nothing but soft parts and don't fossilize well -- so it's hard to say exactly how long the clade's been around. Our best guess is that they diverged from the vampyromorphs sometime in the Devonian, or ~360 mya (!), though of course octopuses of that era might not have been very smart. Given the clade's modern diversity, though, octopuses seem likely to have been fairly intelligent as animals go for a very long time. That's suggestive of a soft filter of some sort; two possibilities might be their short lifespans (octopuses rarely make it five years, and die soon after mating) or the fact that they're largely solitary animals. Some squid, however, are more social. Cetaceans are a much younger clade, having evolved from wolf-like ancestors (albeit more closely related to cows) in the Eocene. And their intelligence is probably younger still; if encephalization quotient is anything to go by, archaeocetes were dumb as rocks []. Unfortunately, most cetacean species are poorly researched, cognitively speaking, so we can't nail down the evolutionary timeline with precision.
3Lumifer6yThat's an awesome name X-D Even better, the sole living representative of the order is Vampyroteuthis infernalis, lit. "vampire squid of Hell", says Wikipedia.
2CCC6yPersonally, I would consider them "filtered out" if and when they go extinct. So they may still have quite a bit of time left.

I suspect you are correct that the great filter does not lie between urbilatiran and dophin intelligence, but I did think of one possible hole in the argument (that I don't think is likely to end up mattering). It is possible that instead of it being easy in general for something like an urbilatiran to evolve significant intelligence, it might only be easy on places like Earth. That is, while there exist environmental conditions under which you would expect an urbilatiran-level organism to easily evolve to dolphin level in several independent instances, such conditions are very rare, and on most planets where urbilatiran-level organisms evolve, they don't advance much further.

6Stuart_Armstrong6ySo far we haven't seen any evidence the Earth is particularly rare, I think.
3[anonymous]6yA few astronomical studies have come out this year giving evidence that Earth is actually more common than we thought, in terms of geology among planets within this galaxy.
8CellBioGuy6yCan you elaborate/point us in their direction?

Getting from dolphin to human intelligence is unlikely.

I think this is my current favorite (but not by much): it seems to me that the evolution of human intelligence from ape intelligence may have been contingent on several geographic factors of the early pre-human environment, and a planet where those features don't occur could be teeming with intelligent life, but nothing quite intelligent enough. But I'm not a geologist who could estimate how many randomly chosen planets would have those features.

3Toggle6yCould you clarify which geographic features you mean? Off the top of my head, I am thinking of the savanna, (which favors height and endurance running, indirectly freeing up hands for tool use) and possibly fluctuating sea level due to glacial/interglacial cycling.
2Vaniver6yI am not an expert in human prehistory, and I remember reading this account as being speculative the last time I looked into it, so take the following with a grain of salt. That said, it seems that several features of modern humans evolved separately in different environments- color vision in the jungles to identify fruits, standing upright (which led to more useful hands) in the savannah, easy access to micronutrients useful for brain development along rivers and the coast. So if a planet has savannahs and coastline and jungles, but not next to each other like they were in Eastern Africa during the relevant timeframe, then the path that we took is blocked (or, at least, harder to follow). But how easy are alternate paths, and how likely is a habitable planet to support at least one pathway like that? I don't have the expertise to guess well.
4Azathoth1236yIt's not clear why color vision is necessary for intelligence. In any case most vertebrates have (at least) three color vision. In most mammals this was reduced to two but in primates a mutation increased this to three. So its not like three color vision is hard to evolve.
1Vaniver6yI think the more stuff your brain does for you, the more you benefit from any gene that benefits your brain. But is 3-color vision all that different in this regard than 2-color vision? Perhaps not.
1Azathoth1236yI'm not sure about that it seems that the higher up the evolutionary tree you go the more the emphasis shifts from "more senses" to "better use of fewer senses". Sharks can detect bio-electric fields and minute water vibrations for example.
2Toggle6yIt's hard to argue that anyone does, I suppose. The narrow argument would be that, temporally speaking, savannas and colored fruits are rare even on Earth. For any solar-powered primary producer in any theoretical biosphere, there is a basic evolutionary height advantage- you increase the percentage of the time you are in sunlight, spread reproductive tissues over a wider area, and cast shade on nearby competitors. As soon as Earth plants developed vascular systems for vertical nutrient transport (~350 million years ago), forest-morphologies began to dominate the most fertile land areas, so that open areas correlated with geographically distant harsh conditions or a lack of nutrients (deserts, tundra, inland mountains). The last 60 million years or so have been the exception to this rule, leading to the distinctive savanna ecosystems of the Cenozoic. They really took off after an evolutionary innovation in photosynthesis, C4 carbon fixation [] , which has its own environmental contingencies. The drought tolerance and efficiency in carbon fixation of these plants are responsible for the existence of 'fertile' areas that also have high visibility- and in particular, the close proximity of dense forests and open plains (and coastlines where there are coastlines). As such, the geographic feature is highly contingent on a specific evolutionary pathway within a particular atmospheric regime- and the window could have been closed after a brief period of time by further developments. The broader argument would point out that, as the wiki page notes, C4 carbon fixation evolved independently a lot, implying that it is closely adjacent to many plant types. The 'height race' in terrestrial primary producers may even increase the probability of this development, since it exacerbates the problem of evapotranspiration. If our method of chemical photosynthesis is a common first step in

I will again try for a poll.

Where do you think the great filter most likely lies:


Can somebody explain to me why people generally assume that the great filter has a single cause? My gut says it's most likely a dozen one-in-a-million chances that all have to turn out just right for intelligent life to colonize the universe. So the total chance would be 1/1000000^12. Yet everyone talks of a single 'great filter' and I don't get why.

3[anonymous]6yI don't think anyone really assumes that.
9Sophronius6yMaybe not explicitly, but I keep seeing people refer to "the great filter" as if it was a single thing. But maybe you're right and I'm reading too much into this.
3Luke_A_Somers6yNormal filters have multiple layers too - for example first you can have the screen that keeps the large particles out. Then you have the activated charcoal, and then the paper to keep the charcoal out, and for high-end filters you finish off with a porous membrane. And yet, it's all one filter. SO... we're speculating here on where the bulk of the work is being done. The strength could be evenly distributed from beginning to end, but it could also be lumpy.
4[anonymous]6yFrom the OP: That's very non-obvious to me; I can't see why there couldn't be (say) a step with probability around 1e-12, one with probability around 1e-7, one with probability around 1e-5, one with probability around 1e-2, and a dozen ones with joint probability around 1e-1, so that no one step comprises the majority (logarithmically) of the filter.
2torekp6yGood point, but note that in your example, the top filter does a lot more than the runner-up. There could be a lot of value in knowing what that top one is, even if the others combined are more important. (But that wouldn't answer the question, how much danger do we still face? Which may be the biggest question. So again - good point.)
7[anonymous]6yIt is. But even there, I'm under the impression that many people are focussing on the answers “most of it” and “hardly any” neglecting everything in between. -------------------------------------------------------------------------------- A few possible hypotheses (where by “supercomputers” I mean ‘computation capabilities comparable to those available to people on Earth in 2014’): 1. Nearly all the filter ahead. A sizeable fraction of all star systems have civilizations with supercomputers, and about one in 1e24 of them will take over their future light cone. 2. Most of the filter ahead. There are about a million civilizations with supercomputers per galaxy in average, and about one in 1e18 of them will take over their future light cone. 3. Halfway through the filter. There is about one civilization with supercomputers per galaxy in average, and about one in 1e12 of them will take over their future light cone. 4. Most of the filter behind. There is about one civilization with supercomputers per million galaxies in average, and about one in a million of them will take over their future light cone. 5. Nearly all of the filter behind. There have been few or no other civilizations with supercomputers than us in our past light cone, and we have a sizeable chance of taking over our future light cone. ISTM people push too much of their probability mass near the ends and leave too little in the middle for some reason. (In particular, I'm under the impression that certain singularitarians unduly privilege hypothesis 5 just because they can't imagine a reason why we will fail to take over the future light cone -- which is way too Inside View for me -- and they think the only thing left to know is whether the takeover will be Good or Bad.) I think there's pretty little practical difference between 3 and 4 (unless you value us taking over the future light cone at somewhere betw
3[anonymous]6yBTW, I think that 1 is all but ruled out (and 2 is slightly disfavoured) by the failure of SETI (at least if you interpret the present tense to mean ‘as of the time their wordline intersects the surface of our past light cone’), and 5 is unlikely because of Moloch [] (if he's scary enough to stop cancer from killing whales [] he's totally likely to be scary enough to stop > 99.9% of civilizations with supercomputers from taking over the light cone). My own probability distribution has a broad peak somewhere around 4 with a long-ish tail to the left.
1peter_hurford6yFrom the article: That doesn't sound like it admits the possibility of twelve, independent, roughly equally balanced filters.
1[anonymous]6yYou're being uncharitable. "[It's] likely [that X]" doesn't exclude the possibility of non-X. If you know nothing about a probability distribution, it is more likely that it has one absolute maximum than more than one.
9peter_hurford6yMaybe I am being uncharitable, but when Sophronius asks "[c]an somebody explain to me why people generally assume that the great filter has a single cause?" and you reply "I don't think anyone really assumes that", I have to admit that I've always seen people think of the Great Filter in terms of one main cause (e.g., look to the poll in this thread where people choose one particular cause), and not in terms of multiple causes. Though, you're right that no one has said that multiple causes is outright impossible. And you may be right that one main cause makes a lot more sense. But I do think Sophronius raises a question worth considering, at least a bit.
5AnthonyC6yAt least in other Less Wrong posts and comments on the topic, the question is usually presented probabilistically, as in "Does the bulk of the great filter lie ahead of us or behind us?" Though, it is usually not specified whether the writer is asking where the greatest number of candidates gets ruled out, or the greatest fraction. Maybe there are ten factors that each eliminate 90% of candidates prior to the technological civilization level (leaving maybe a hundred near-type-I civilizations per galaxy), but one factor (AI? self-destruction by war or ecological collapse? Failing to colonize other worlds before a stray cosmic whatever destroys your homeworld?) takes out 99% of what is left. In that case nearly all the great filter would be behind us, and our odds still wouldn't be good.
1amcknight6yI don't have an answer but here's a guess: For any given pre-civilizational state, I imagine there are many filters. If we model these filters as having a kill rate then my (unreliable stats) intuition tells me that a prior on the kill rate distribution should be log-normal. I think this suggests that most of the killing happens on the left-most outlier but someone better at stats should check my assumptions.
1Galap6yI'd liken it to a chemical reaction. Many of them are multistep, and as a general statement chemical processes take place over an extremely wide range of orders of magnitude of rate (ranging from less than a billionth of a second to years). So, in an overall reaction, there are usually several steps, and the slowest one is usually orders of magnitude slower than any of the others, and that one's called the rate determining step, for obvious reasons: it's so much slower than the others that speeding up or slow down the others even by a couple of orders of magnitude is negligible to the overall rate of reaction. it's pretty rare that more than one of them happen to be at nearly the same rate, since the range of orders of magnitude is so large. I think that the evolution of intelligence is a stochastic process that's pretty similar to molecular kinetics in a lot of ways, particularly that all of the above applies to it as well, thus, it's more likely that there's one rate determining step, one Great Filter, for the same reasons. However (and I made another post about this here too), I do think that the filters are interdependent (there are multiple pathways and it's not a linear process, but progress along a multidimensional surface.) that's not really all that different than molecular kinetics either though.
1Sophronius6yInteresting. However, I still don't see why the filter would work similarly to a chemical reaction. Unless it's a general law of statistics that any event is always far more likely to have a single primary cause, it seems like a strange assumption since they are such dissimilar things.
0Galap6ySorry for the delayed response; I don't come on here particularly often. The assumptions I'm making are that evolution is a stochastic process in which elements are in fluxional states and there ere is some measure of 'difficulty' in transitioning from one state to another, an energetic or entropic barrier of sorts, that to go from A to B (for example, from an organism with asexual reproduction to an organism with sexual reproduction) some confluence of factors must occur, and that occurrence has a certain likelihood that's dependent on the conditions of the whole system (ecosystem). I think that this combined with the large numbers of physical elements interacting (organsims) is enough to say that evolution is governed by something pretty similar to statistical thermodynamics. So, from the Arrhenius equation, k = Ae^{{-E_a}/{RT}} where k is the rate of reaction, A is the order of reaction (number of components that must come together), E_a is the activation energy, or energy barrier, and RT is the gas constant multiplied by temperature. The equation is mostly applied to chemistry, but it also has found uses in other sectors, like predicting the geographic progression of the blooming of Sakura trees ( []). It really applies to any system that has certain kinetic properties. So ignoring all the chemistry specific factors (like temperature), the relation in its most general form becomes k = Ae^-BE This says essentially that the rate is proportional to a negative exponential of the barrier to the transformation, and small changes in the value of the barrier correspond to large changes in the value of the rate. Thus, it's unlikely that two rates are similar. I don't see why two unrelated things would be likely to have a similar barrier, and given this, they're even less likely to have a similar rate.
1ChristianKl6yPareto principle. There also the Fermi formula.
6FiftyTwo6yI think you need to explain your meaning more
4wadavis6yThe Pareto principle is the 80-20 rule. Meaning if there are 4 great filters each with an effectiveness of 0.9,0.9,0.99, and 0.9, it will be the 0.99 filter that requires ten times the attention / luck and will get the name 'Great', even if there are many other hurdles adding to the end result. This is a troubleshooting problem where we are still on the first stage of the diagnosis: Identifying the largest contributor to the problem, identifying the low hanging fruit. The whole filter that prevents life on every planet is going to the a combination of many stacked smaller filters, but we want to find the most relevant filter, either the 0.999 filter or the locally relevant filter. This discussion is all part of that diagnostic process to find the most relevant single cause.
[-][anonymous]6y 12

To whoever voted for “Multi-cell life unlikely”: Multicellularity has evolved independently at least 46 times.

5William_Quixote6yI voted for that, but my view is a bit more fine grained. I think complex multicellular life with efficient energy is rare. My view is based on the fact that there was life about as soon as possible on earth but it took billions of years to get mitochondria and large complex multicellular life. Once you got that you had a very rapid explosion and tons of highly complex species within a few hundred million years. And multiple fairly intelligent species within a few hundred million after that. My assumption is the step with the longest gap is the most unlikely piece.
1[anonymous]6yWait... don't all eukaryotes have mitochondria, including unicellular ones? I think “Complex single cells unlikely” on the poll is a better fit to your position.
6CellBioGuy6yIt is worth noting that there are numerous examples of endosymbiosis all over the tree of life and the mitochondrion and plastids aren't the only ones, just the most successful and most ancient. There are bacteria that have bacterial endosymbiotes, and I've seen electron micrographs of large bacteria with strange uncharacterized archaea hanging off them like tassles. Some animals, mostly insects that drink plant sap, have endosymbiotic bacteria that have had their genomes stripped down to only 150 genes and cannot make their own cellular energy that only exist to make essential amino acids so that the animal does not have to eat them. Large numbers of photosynthetic microbes have taken up eukaryotic green algae as second-order endosymbiotes, or even have taken those organisms up as tertiary endosymbiotes. EDIT: here's a chart [] of the bizarre known history of clades acquiring photosynthesis via known primary, secondary and tertiary endosymbiosis. By the time you are at tertiary endosymbiosis, the plastid has 6 nested membranes and may have some vestigial nuclei between some of them.
1William_Quixote6yYeah, somewhat. I think what I was getting at by complex multi cellular life is that I think the cambian explosion [] is rare.
3CellBioGuy6yIt is worth noting that the Cambrian also coincided with the Earth releasing from an ice age that makes everything since look mild, as well as the increase of atmospheric oxygen to levels within an order of magnitude or two of today. It is also worth noting that there is equivocal evidence of multicellular life before the Cambrian that nobody quite agrees on what it means - things that look like worm-trails in seafloor sediment a billion years old (but that some think could be trails from the motion of giant protists []), flat sheets [] with a distinct center and edge 2 gigayears old, and macroscopic curly fibers [] two or more gigayears old...
1[anonymous]6yWhy did it take 0.6 billion years from Eukaryotic cells to simple multi-celled organisms?
1[anonymous]6yDefine "independently."
3CellBioGuy6yI'm wary of calling cyanobacteria with their specialized nitrogen-fixer cells or the various colonial sporangia-forming bacteria 'multicellular'. They do some hellacious cell specializing within colonies, and there are other bacteria that form chains between reducing and oxidizing environments with bacteria in the middle passing electrons back and forth so as to allow the whole colony to metabolize things one bacterium couldn't, but it's arguably a little different than what we think of when we think of a mushroom or an animal. Eukaryotes have however evolved unambiguous multicellularity on many occasions.
2[anonymous]6yIn lineages not directly discended from one another (though they do have a common (unicellular) ancestor). According to the article I linked to it even happened to prokaryotes, though “complex” multicellular organisms (whatever that means -- I guess cells not only bound together but also specialized?) ‘only’ evolved six times among eukaryotes. It is possible that eukaryotes are particularly propense to becoming multicellular the way the OP claims bilaterians are propense to becoming intelligent, but I'd interpret each item of the poll to be conditional on all of the above, and I'd take “complex single cell life” to mean eukaryotes on Earth or similar.
7FeepingCreature6y[x] other reasons What if we're the first in a winner-takes-all scenario? If the first-mover prevents (or vastly reduces the likelihood of) the evolution of latter intelligent life, intelligent life should not be surprised by being the first intelligent species to evolve.
1pinyaka6yThat we're not that special is an assumption of the Great Filter argument. We could be the first intelligence to arrive on the scene, but it probably will be more harmful to underestimate upcoming pitfalls than overestimating them.
3[anonymous]6yI answered "Complex single cell life unlikely" simply because it took the longest time - 1.6 billion years - to develop.
1Stuart_Armstrong6yA very valid point.
3[anonymous]6yThe logic is actually from Hanson's "The Great Filter" essay. []
1[anonymous]6yI voted "see results only". Based on the wide, unconcentrated distribution of evidence and beliefs about the so-called Great Filter, I think an option has been excluded: there is no Great Filter, and we are only one among many intelligent species in the universe (or even in this one galaxy) on one among many planets to develop such. Other intelligent life may well be totally unlike us, or, very rarely, parallel evolutionary pressures might have operated and produce something whose mentality we could almost understand. We don't know. We do know that our world hasn't been strip-mined by a long-since-transhuman intergalactic supercivilization... but that's not really good evidence that no other intelligence has evolved in our light-cone at all. This whole thing has too much an air of mystery for me to believe we really understand it.
3[anonymous]6yThat would be a late Filter (between intelligence and intergalactic supercivilization).
5CellBioGuy6yI think calling it a "filter" implicitly primes people for the impression that the options are supergalactic civilization or death, and to exclude possibilities where things keep going but don't become astronomically visible.
1Stuart_Armstrong6yWhat about central nervous systems?
1Gunnar_Zarncke6yI took the list from wikipedia (except for added differentiation after now).

Alternative anthropic principle: There must be a first Type 3 civilization.

3Stuart_Armstrong6yYes, that's one explanation. Though that doesn't explain why the Earth is a late Earthlike planet, rather than an early one.
2Decius6yEarth could also be an early Oth-like planet, the first to contain the unique combination of features that we would immediately recognize in retrospect.
1Stuart_Armstrong6yDo you have any candidates for these features? Because there are two ways of seeing your argument: a) There are some very rare features (like the moon) that are necessary for life. This makes intelligent life very rare. b) There are some features that Earth has that are necessary for life, and Earth is one of the earliest planets with these features. a) explains the Fermi paradox by rarity of intelligence, while b) explains it by saying the first intelligence will expand and prevent other from developing independently. But b) requires that we guess what these features could be.
3Nornagest6yLarge moons are rare, but very rare? The Pluto/Charon system is even more extreme than the Earth/Moon in that respect, although obviously it formed under different conditions.
3Azathoth1236yWell, one unusual feature of Earth are the hybrid solar eclipses [], caused by the sun and moon having the same apparent diameter. Seems like an extraordinary coincidence that Earth should have this feature in the exact epoch when intelligent life evolved.
2Decius6yGood point; lottery-low odds are inadequate to explain the paradox. Literally astronomical odds against a feature of Earth would be required. "Has been observed to not have a large moon" is not something that we can say about 99% of observed planets.
1Decius6ySuppose I had a hypothesis about something that was present in many Earth-era planets but not astronomically younger planets. How would I falsify such a hypothesis? I don't think something with lottery-low odds like the moon would adequately explain the paradox. I also recognize the possibility that Earth might not ever become a Tegmark I civilization, much less a III.
3Stuart_Armstrong6yDepends on the hypothesis. We have some pretty good picture about the development of the Milky Way. If your theory was about rates of supernovas or a certain proportion of heavy metals, then we could check whether those happened recently. If it was more specifically about Earth-like planets, we could record the hypothesis, and check it in a few years or decades as our picture of Earth-like planets around other stars gets clearer.
1Decius6ySilly me. "Suppose I had a hypothesis that all Earth-era and earlier planets shared some feature that some later planets don't." Given that we don't know what the requirements are to be a galactic phenomenon, figuring out which one we don't have is impossible.
1Stuart_Armstrong6yThen we can do the reverse approach - crush all the data we do know, and see what changed about the time our Earth came around. We can then take all these candidates, and check whether any seem plausible, then do some further investigation.
2Decius6yWhile not logically impossible, a test that requires an astronomical amount of time to attempt is not something I can update on. That said, there is a fairly low prior that the conditions for a galactic civilization to develop in the current era are better than they were last era. There is, however, quite a bit of evidence that there is not currently a galactic civilization.

For what it's worth, my personal judgement is that the filter lies before the creation of a central nervous system.

Why? Having dabbled a bit in evolutionary simulations, I find that, once you have unicellular organisms, the emergence of cooperation between them is only a matter of time, and from there multicellulars form and cell specialization based on division of labor begins. Once you have a dedicated organism-wide communication subsystem, why would it be unlikely for a centralized command structure to evolve?

My personal guess would be that the great... (read more)

6[anonymous]6yOn Earth multicellularity arose independently several dozen times but AFAIK only animals have anything like a central nervous system.
2PeterisP6yIf animal-complexity CNS is your criteria, then humans + octopuses would be a counterexample, as urbilaterals wouldn't be expected to have such a system, and the octopus intelligence has formed separately.
4Nornagest6yThe last common ancestor of humans and octopuses probably didn't have a very complicated nervous system, but it probably did have a nervous system: most likely a simple lateral cord with ganglia, like some modern wormlike animals. That seems to meet the criteria for shminux's "dedicated organism-wide communication subsystem".
4[anonymous]6ySee James Miller here [] . Sure, the space of possible value systems is vaste, but I doubt that much less than (say) 0.1% of them would lead agents to try and take over the future light cone, so this could at most explain a small fraction (logarithmically) of the filter.
1Luke_A_Somers6yThat quote doesn't rule out it being before the earliest thing you mentioned.
1shminux6yRight, of course. My mind inserted "right before" without a good reason.
1Stuart_Armstrong6yAnd I implicitly did mean "right before", so your reading was correct.
1The_Duck6yI'm very curious: in what evolutionary simulations have you seen these phenomena evolve?
4shminux6yIf I recall, you start with a single cell like an amoeba, which has to be smart enough to not accidentally eat its own pseudopods, so the relevant mutation sticks, and results in it also not eating its clones and other cells of the same type. This only sticks if there is enough food around so that there is no competition between them. This is how you get cooperation with the same kind. At this point the mutation disappears if you reduce the food supply, as defection (evolving cannibalism) becomes the dominant adaptation. However, if you provide the right conditions for the collections of cells (colonies) to win over single cells (because feeding in packs gives you better odds of eating vs being eaten), then the simple defections do not stick, as single defectors lose to colonies of cooperators. The most fit organisms are those which create colonies right away, with each division, not waiting for a chance to cooperate. Once you have cell colonies competing, the division of labor is next. A relatively simple mutation which lets a cell to become either a hunter, if it is outside-facing, or a food processor, if it is surrounded by the same kind during the first part of its life, is a simple model of how cell specialization might appear. Colonies with two kinds of dedicated cells are more efficient and win out. And so on. The immune system also appears naturally, as hunter cells already perform this role. The models above are, naturally, a gross oversimplification, but they show how the multicellulars could evolve. The simulation code itself is almost trivially simple, I can probably dig it out at some point. I don't recall doing much more than what I've described, but presumably a communication subsystem would increase genetic fitness, eventually resulting in the appearance of the nervous system. I kind of lost interest when it got overly complicated to code. I bet there are people out there who do this for a living.
2RichardKennaway6yThere's this Ph.D. thesis [] and video [] all about multicellular coordination in slime moulds. This is an organism which switches between unicellular and multicellular habits, with cell specialisation, and competition among cells to be among those that make spores and get their genes into the next generation.

"Note that AI is certainly not a great filter: an AI would likely expand through the universe itself"

I was confused by this, what is it supposed to mean? Off the top of my head it certainly seems like there is sufficient space between 'make and AI that causes the extinction of the human races or otherwise makes expanding into space difficult' and 'make an AI that causes the extinction of the human race but which goes on to colonize the universe' for AI to be a great filter.

6James_Miller6yThe universe has a limited amount of free energy. For almost any goal or utility function that an AI had, it would do better the more free energy it had. Hence, almost every type of hyper-intelligent AI that could build self-replicating nanobots would quickly capture as much free energy as it could, meaning it would likely expand outwards at near the speed of light. At the very least, you would expect a hyper-intelligent AI to "turn off stars" or capture there free energy to prevent such astronomical waste of finite resources.
2pinyaka6yAn AI should only avoid wasting energy if energy were a resource that was limiting the maximization of their utility function. If you're a gold-ingot-manufacturing-maximizer, you don't need all the energy available from your star because there isn't enough gold to use it. Even if you're converting everything that isn't a gold ingot in your system into seeds for turning other star systems into gold ingot factories, it's not obvious (to me at least) that you need all the energy available to do that.
5PeterisP6yA gold-ingot-manufacturing-maximizer can easily manufacture more gold than exists in their star system by using arbitrary amounts of energy to create gold, starting with simple nuclear reactions to transmute bismuth or lead into gold and ending with direct energy to matter to gold ingots process. Furthermore, if you plan to send copies-of-you to N other systems to manufacture gold ingots there, as long as there is free energy, you can send N+1 copies-of-you. A gold ingot manufacturing rate that grows proportionally to time^(n+1) is much faster than time^n, so sending N copies wouldn't be maximizing. And a third point is that if it's possible that somewhere in the universe there are some ugly bags of mostly water that prefer to use their atoms and energy for not manufacturing gold ingots but their survival; then it's very important to ensure that they don't grow strong enough to prevent you from maximizing gold ingot manufacturing. Speed is of the essence, you must reach them before it's too late, or gold ingot manufacture won't get maximized.
2pinyaka6yAre you saying that because gold can be produced that energy is always going to be the limiting factor in goal maximization? That was an example, not a proof. The point was that unless energy was the limiting factor in meeting a goal, you wouldn't expect an arbitrarily intelligent AI to try to scrape up all available energy. Earlier tonight, I had a goal of obtaining a sandwich. There is no way of obtaining a sandwich that involves harnessing all the free energy of our sun or expansion into other solar systems that would be more efficient than simply going to a sandwich shop and buying one, thus any arbitrarily intelligent AI would not do those things if it took on the efficient obtainment of my sandwich as a goal. Again, this is just an example that is meant to show that the mere existence of AI does not necessarily require an AI to "turn off stars" as James_Miller was saying you'd expect to see "for almost any goal or utility function than an AI had."
6Stuart_Armstrong6yTo be absolutely certain that you obtain that sandwich, that it's a genuine sandwich, that no-one steals it from you, that you cana lways make a replacement if this one goes bad or quantum tunnels, etc... you need to grab the universe. Grabbing the universe only adds a tiny, tiny bit of extra expected utility, but since there is no utility drawback to doing so, AIs will often be motivated to do so. Bounded utility doesn't save you (though bounded satisficing would, but that's not stable [] ).
3pinyaka6yOK. Replace "efficient" with quick. Getting me a sandwich within a short amount of time precludes being able to take over the universe.
1Stuart_Armstrong6yThat seems safer (and is one of the methods we recommended in our paper on Oracles). There ware ways to make this misbehave as well, but they're more complex and less intuitive. Eg: The easiest way this would go wrong is if the AI is still around after the deadline, and now spends its effort taking over the universe in order to probe basic physics and maybe discover time travel to go back and accomplish its function.
2James_Miller6yYou are forgetting about quantum uncertainty. There is always a chance that all of the gold on earth will jump to a blackhole. The more free energy you have, the more you can reduce this probability.
2[anonymous]6yIt rests on the hypothesis that the AI is not only dangerously intelligent but able to self-improve to levels where it can more-or-less direct an entire civilization's worth of material infrastructure towards its own goals. At that point, it would have an easy time getting a space program going, mining resources from the rest of its solar system, and eventually, achieving interstellar existence (via the sheer patience to cross interstellar distances at sublight speeds).

Regarding anthropics, specifically this:

Is intelligence hard to evolve? Well, we're intelligent, so it must be easy... except that only an intelligent species would be able to ask that question, so we run straight into the problem of anthropics. Any being that asked that question would have to be intelligent, so this can't tell us anything about its difficulty

I think the line of reasoning is valid, it's just that there's a lot of confusion about probabilities and events to which the probabilities apply. Of course the probability of life arising - once... (read more)

0[anonymous]6yDon't think this works. For all we know, the vast majority of possible universes are entirely dead, and only our tiny backwater of configuration space happened upon the right low-probability event. The probability of life existing given that we're in a configuration with life in it is of course 1, but we can't use that to derive a high probability for abiogenesis without independent data points, which we don't have. (This is unlikely to actually be the case, of course -- unicelluluar life appeared so early in our planet's history that we can't pinpoint it with stratigraphic methods, which is unlikely if abiogenesis were the hard part. But we're talking unlikely, not impossible or nearly impossible.)

I'm sorry but I think this article's line of reasoning is irreparably biased by the assumption that we don't see any evidence of complex technological life in the universe. It's entirely possible we see it and don't recognize it as such because of the considerable difficulties humans experience when sorting through all the data in the universe looking for a pattern they don't recognize yet.

Technology is defined, to a certain extent, by it's newness. What could make us think we would recognize something we've never seen before and had no hand in creating? M... (read more)

4Stuart_Armstrong6yYes, it's possible. But that argument proves too much: any observation could be advanced technology that we "don't recognize [...] as such". The fossil record could be that, as far as we can tell, etc... We have to reason with what we can reason with, and the setup of the universe - galaxies losing gas and stars, stars burning pointlessly into the void, supernovas incredibly wasteful of resources, etc... - all points to natural forces rather than artificial. It still could be artificial, but there's no evidence of it.
2JoshuaMyer6ySomething which cannot be observed and tested lays beyond the realm of science - so how big a signal are we looking for? A pattern in quasar flashes perhaps? Maybe the existence of unexplained engineering feats from civilizations long dead? The idea that advanced technology would want us to observe it, the existence of vague entities with properties yet to be determined ... these exist as speculations. To attempt to discern a reason for the absence of evidence on these matters is even more speculative. Perhaps I should clarify: none of the data discussed really helps us narrow down a location for the filter because we aren't really discussing methods of testing the filter. It's existence is speculative by design. You can't test for something as vaguely defined as intelligent technology. I do agree that examining other species may yield a better conceptualization of intelligence. I very much like that the discussion has drifted in that direction.
2Stuart_Armstrong6yI'm more thinking of mega engineering projects, the reforming of galaxies to suit the needs of a civilization, rather that the messy randomness and waste of negentropy that we seem to see. I'm not assuming that advanced technology would want us to observe it - I'm assuming that advanced technology has no reason to stay hidden from us, at tremendous opportunity costs for it.
1JoshuaMyer6yWhy? Anything massive traveling between stars would almost certainly be either very slow turning, constantly in search of fuel, or unconstrained by widely accepted (though possibly non-immutable) physical limitations ... Would we be a fuel source? Perhaps we would represent a chance to learn about life, something we believe to be a relatively rare phenomena ... There's just not enough information to say why an entity would seek us out without assuming something about its nature ... intelligence wants to be seen? To reformat the universe to suit it's needs? An interesting concept. It certainly can evolve as an imperative (probably in a more specific form). Perhaps you could refer me to more writing on the subject. I've been imagining Von Nueman machines crawling through asteroid belts -- Arthur C. Clarke chases them away from a first contact scenario by convincing them we will never conquer the stars. Clearly, I'm missing some links. Oh and thank you for engaging me. The way you deal with concepts makes me happy.
2Stuart_Armstrong6yWe argue that travelling between galaxies - let alone between stars is very "easy", for some values of "easy". See [] or [] Major cosmical restructuring would be trivial (under the assumptions we made) for any star-spanning civilization.
2JoshuaMyer6yThank you. Not entirely convinced, but at least I'm distracted for now by not knowing enough astrophysics. :-)
0CCC6yHmmm... reformatting a galaxy to suit the needs of a civilisation will likely mean using all the energy that that galaxy produces internally. If the energy is all being used internally, then it stops broadcasting in the form of electromagnetic radiation; the galaxy goes dark. The same would apply to a solar system; entirely reformatting a solar system to the needs of a civilisation would mean that, to an external observer, the sun would go dark. The system could only be observed by its gravitational potential, not by any energy it puts out. ...which, now I come to think of it, would make that solar system indistinguishable from dark matter, would it not?
4Azathoth1236yYou still have to get rid of waste heat, you can't recycle it because of the second law of thermodynamics. So they'd radiate highly in the infrared. Incidentally, there is an object [] in the Triangulum galaxy that's dim in the visible and near-infrared but the most luminous thing in that galaxy in the mid-infrared.
2CCC6yWaste heat. Sorry, my internal editor cringes at that... As to the object, I notice something interesting. In the writeup: And then I look at the paper - and it was submitted in December 2010, only a few years ago. Which then leads to the question - has anyone looked for things that are dim in near-infrared but bright in far-infrared? Do we actually know how much apparent dark matter is (or isn't) pumping out waste heat all over the place? (That is a very interesting page, by the way...)
2CellBioGuy6yIt's also extremely bright in total luminosity across the spectrum (including infrared) - 100,000x as bright as the Sun. Other similar objects have been seen as supernova sources in other galaxies, suggesting they are massive stars shrouded in self-produced dust which blocks visible light but lets IR through. If this is the case, various models suggest we should see the dust around this thing clear in decades to centuries - or a supernova. You can bet people are watching it closely though...

I'm extremely curious: how did you come to conclude that the Great Filter was probably a particular evolutionary leap?

1Stuart_Armstrong6yUsing bad reasoning: intuition and subjective judgement. The chances of a late great filter just don't seem high enough...
1Paul Crowley6yWhat do you make of Katja Grace's SIA-based argument for a late Filter?
2Stuart_Armstrong6yI no longer believe that anthropic probabilities make sense (see [] and subsequent posts - search "anthropic decision theory" in less wrong), only anthropic decisions do. Applying this to these situations, total utilitarians should (roughly) act as if there was a late filter, while average utilitarians and selfish beings should act as if was an early filter.

Bonobos are one of Earth's most intelligent species, and seem much kinder than humans. The existence of altruistically motivated human inventors like Stanford R. Ovshinsky and Douglas Engelbart suggests that being bonobo-level kind would not prevent technological development.

This seems like evidence against certain kinds of late Great Filters.

Another point: I imagine if we had evolved from bonobos, we would be doing effective altruism on a much larger and better scale than we are now, for instance. So based on the existence of bonobos, one could argue th... (read more)

4skeptical_lurker6yGiven that ants developed agriculture despite having tiny brains, I would imagine that it might be easier for eursocial animals to develop a technological civilisation, which provides more evidence against these filters.
2Lumifer6yDo they now? Looking at the Wikipedia page you linked to...
3John_Maxwell6yI'm not claiming that they're some paragon of peace and cooperation, just that they seem substantially more peaceful and cooperative than humans do. E.g. []
2Azathoth1236yHow many bonobos are there in captivity? How many non-bonobo chimps have killed other chimps?

With at least three intelligent-ish species on earth, while there is only one technological species, intelligence would not seem to be a great filter.

The things that allow us to be technological seems to me to be at least these four things occurring in parallel: 1) intelligence, 2) complex language, 3) dexterity, 4) an "instinct" to trade. Ridley suggested in Rational Optimist that other apes lack the instinct to trade even when we teach them language. I have no idea how this hypothesis fares in the wider world.

The great filter could concei... (read more)

6Lalartu6yHe is just plain wrong [] []
1mwengler6y|He is just plain wrong That might be overstating it. In both the articles you cite, some Apes are able to do some exchanges when the situation is set up for them by experimenters. Neither article reports exchanges occurring outside of highly artificial laboratory situations set up by humans, and the 2nd article states right in its abstract that
1AshwinV6yCould you perhaps elaborate on the apes part? Or rather how the difference between the "instinct to trade" and "language" ended up being distinguished as such? I somehow think of the two as being extremely inter-related, language (in its rudimentary form, not the advanced language of humans that humans such as Orson Scott Card use) would probably be used in all ways to obtain a sort of 'comparative advantage', as opposed to a species that doesn't use language. It is in essence a tool used to obtain/give aid, and I cant think of another purpose why it would evolve suo moto. Therefore, I may want to take issue with Ridley's claim that apes were "taught Language"(it sounds to me like they were thought words and corresponding actions or the rough equivalent of that). Nevertheless, it is an interesting theory and I would like to know more.
1mwengler6ySome references in a review of Ridley's Rational Optimist [] describing claims about Apes not being able to barter and exchange the way humans do. Not quite on the apes but this [wsj article by Matt Ridley[( []) talks about how exchange was the unique innovation of humans that caused our achievements and that evidence is that Neanderthals didn't have exchange the we did.

My current estimates lead me to think either AI is hard, the filter is already behind us or there are implementable "mundane" solutions to existential risk. Or technological risk/progress on earth is very unusual (maybe some organisms would never be tempted to use a nuke as they are too "emotionally" connected to the pain of other members of their species).

Consider the following possibilities for how long it will take for humans to develop AI (friendly or otherwise) if we don't kill ourselves via viruses, nuclear catastrophe etc.

30 ye... (read more)

1CCC6yYou think that, without using uploads or AI, humanity has less than a 50% chance of surviving the next hundred years? That seems very surprising to me. Viral threats are a danger, yes, but while they may cause massive depopulation, even kill off a significant fraction of Earth's population (especially if genetically engineered viruses are used as a terrorist weapon), they seem unlikely to be able to kill off everyone - especially if people on small islands start shooting down any approaching planes to prevent contamination. Nanotechnological threats may be more all-inclusive, but while that might destroy an entire continent, it would seem unlikely that nanotechnology that can cross an ocean before countermeasures can be developed could be created accidentally And within thirty years, there's even a chance of a small colony on Mars - if they can get to the point where they're growing their own food, rather than having it shipped from Earth, and where they have enough people to sustain their population, then even something that renders Earth uninhabitable would not wipe out all of humanity; and the Sun appears stable enough to keep going for a good few million years still. So... am I misunderstanding you, or do you see some threat to humanity that I fail to notice?
2Lalartu6yThere are other possibilities. One is simply "never", other is that AI is much less powerful than current predictions tell, third that interstellar travel is impossible, fourth that AI singletons don't reproduce and therefore don't colonize. But does not exist. There are lots of problems with this concept. But first, to reduce global risks that requires world goverment, and it almost certainly will stop progress. Chance to have sustainable colony in foreseeble future (~20 years) are close to zero.
1Stuart_Armstrong6yI got two of those three options :-) []

Let's make the further assumption that our common ancestor with dolphins was dumber than the modern octopus. This doesn't seem a stretch seeing how intelligent the modern octopus can be, how minor in terms of ecological role the common dolphin-human ancestor must have been, and seeing the stupidity of many of the descendants of that common ancestor.

Could you expand on the second point, as to why it must have a minor ecological role, and why this means it would be dumber? I know little evolutionary theory, and would appreciate the explanation. Cheers.

2PeterisP6yI'd read it as an acknowledgement that any intelligence has a cost, and if your food is passive instead of antagonistic, then it's inefficient (and thus very unlikely) to put such resources into outsmarting it.
[-][anonymous]6y 0

You assume that going to the stars is a measure of intelligence, and it does seem logical, but what if a comparably intelligent race decided against doing it? For example, if they have a way to live forever on their planet but lack the means to support the same conditions when they leave it, let alone the incentive to change other planets to habitual for them, then developing the star-reaching technology is not a Great Filter for them, but merely a step outward.

0Stuart_Armstrong6yThat's a category of solutions to the Fermi paradox, but it requires uniformity of motive inside a species (no-one will want to expand) and between species (all species will stay put). I've addressed these issues at the end of: []