TL;DR: I think the main arguments in the article miss the point; radio is one of the few classic-physics-allowed means of communication, communication gives a survival advantage, it's highly likely that organisms will develop classic-physics communications and use radio long before they develop other means of communication we don't know about, and thus any species that develops environment-altering intelligence will probably gain an advantage and probably eventually have something like radios. So it's highly unlikely, IMO, that radio is a human "species-specific" trait. This comment is based on my first reading of the linked article.
From the article, the primary argument against the possibility of non-human intelligence-that-builds-radios seems divided in two parts: 1) There is no visible "trend towards" human-like intelligence anywhere on Earth. 2) Even if some species develop "intelligence" and grow that trait, the specific subsets of this that a) give sentience or b) build radios are species-specific traits of humans.
Now, 1) is rather odd and has already been deconstructed elsewhere, and doesn't support the point that strongly, if I understand any of this. A mutation needs to have a noticeable effect on survival or reproductive rates in order to fix in - and I suspect that the intersection of these and mutations that lead towards human-like intelligence is rather small, in the space of possible mutations the various earth organisms can retain. A cursory scan of wikipedia's page on the evolution of human intelligence indicates that even this is rather poorly understood, and my first impression is that many models and theories indicate that our intelligence might have been a runaway feedback loop that would not be observable as a gradual process in other species (apart from observing the gradual development and growth of the requirements, e.g. hands with grip and brain sizes for some models).
As for 2), things here are a bit weird. AFAIK, there's a limited number of methods that individual organisms can transmit information to other individual organisms. I'm willing to consider exotic things that don't resemble anything here on earth, but really, communication between organisms confers some major advantages at many levels, from telling someone else where the predators are hunting to coordinating teamwork to teaching stuff to later generations.
I mean, there aren't 2^700 different possible techniques for transmitting information across organisms, even less to another planet. You've got to send radiations / matter / stuff from A to B. Unless you magically find some way to teleport information. I doubt any organism or intelligence or goal-optimizer or probability constrainer is going to invent teleportation before ever using any form of classical radiation-based information transmission. It's not out of the realm of the possible, but AFAICT the base-minimum configuration of matter required to even entangle two particles and then measure them is far, far more complex than the base-minimum configuration of matter required to transceive light or radio signals. And I hope any apparatus that can actually FTL/teleport/etc information in means unknown to us yet is at least as complex as entangling and measuring qubits (otherwise, what the hell have we been doing? Shouldn't that search subspace have been completely covered already? Feel free to correct me on this if you have better understanding though).
So in the space of things you can do, you can have super-organisms that don't require communication to coordinate, or are just so damn smart and powerful that they don't even need to coordinate to overwhelm all pressures and enemies and predators, or some other communication-obsoleting unlikely scenario... or you have species that communicate, because the game-theoretic advantages they gain from communicating let them win more often, which translates into more of them surviving at the expense of other species or organisms.
And for that communication to happen, you've got to use one of the means that physics allows. Radio and light and other forms of radiation are pretty much hard to avoid in this field, AFAIK. There aren't 2^700 means to get data from A to B. I'm probably missing stuff, but overall if I'm playing the Natural Selection™ game: having multiple reproduction-capable individuals that communicate with eachother regularly using energy radiation / vibrations / rapid matter transfer is probably better, ceteris paribus, than not having those two advantages.
Therefore it stands to reason that in the long run, on average, planet-dominant species will have some form of communication, perhaps akin to language or perhaps more exotic, using known forms of communication at some point in their history, and there will be planet-dominant species whenever one species develops these advantages naturally. Conjecture, but that I believe reasonably argued and more likely than its complement set of possibilities.
On the other hand, based on our own experience, broadcasting radio signals is a waste of energy and bandwidth, so it is likely an intelligent society would quickly move to low-power, focused transmissions (e.g. cellular networks or WiFi). Thus the radio "signature" they broadcast to the universe would peak for a few centuries at most before dying down as they figure out how to shut down the "leaks". That would explain why we observe nothing, if intelligent societies do exist in the vicinity. Of course, these societies might also evolve rapidly soon after, perhaps go through some kind of singularity, and might lose interest for "lower life forms" -- which would then explain why they might not look for our signals or leave them unanswered if they listen for them.
Now that is a good argument that doesn't miss the point. My priors would say it's not even "a few centuries" - I'd expect less than one earth-century on average, with most of the variance due to the particular economic variations and social phenomena derived from the details of the species.
Without any other information, it is reasonable to place the average to whatever time it takes us (probably a bit over a century), but I wouldn't put a lot of confidence in that figure, having been obtained from a single data point. Radio visibility could conceivably range from a mere decade (consider that computers could have been developed before radio -- had Babbage been more successful -- and expedite technological advances) to perhaps millennia (consider dim-witted beings that live for centuries and do everything we do ten times slower).
Several different organizational schemes might also be viable for life and lead to very different time tables: picture a whole ant colony as a sentient being, for instance (ants being akin to neurons). Such beings would be inherently less mobile than humans. That may skew their technological priorities in such a way that they develop short range radio before they even expand out of their native island, in which case their radio visibility window would be nil because by the time they have an use to long range communication, they would already have the technology to do it optimally.
Furthermore, an "ant neuron" is possibly a lot more sophisticated than each neuron in our brain, but also much slower, so an "ant brain" might be the kind of slow, "dim-witted" intelligence that would go through the same technological steps orders of magnitude slower than we do while retaining very high resiliency and competitiveness.
and might lose interest for "lower life forms"
Lower life forms (as lower nonlife) forms are always interesting as a source of free enthalpy and from many other aspects.
You, as an advanced civilization have no luxury of ignoring. You have to engage, the "Prime directive" is a bullshit.
And you don't need to wait for a radio signal. You go there (everywhere) on your own initiative, you don't wait to be invited.
There are a lot of issues with this sort of claim. One that is most often missed is that you don't expect more than one very smart species with tool capabilities to evolve if one expects them to act at all like humans do. Humans have spread out to the entire planet in a short time from an evolutionary standpoint, and we've drastically and rapidly altered pretty much every ecosystem on the planet, in many cases putting major selective pressures on other species against them moving into at all similar niches. And when there is a smart, tool using species, one of the things we do is enslave it for our ends while hunting the wild ones (elephants are one of the good examples).
In this context, this argument isn't maybe that relevant since the authors are trying to look at the last 100 million years and are looking at the encephalization quotient across all species, so this sort of concern matters less for their version of the analysis, and the rest of the idea seems interesting. If so, then some major part of the Great Filter may be simply getting intelligent enough to start a civilization.
A number of species are smarter than others, and some are getting there. Their 'always 0 progress' reading is wrong.
To put it another way, there is no average drift towards larger brains, but individual lineages do have trajectories up or down. Encephalization is one adaptation suite out of many possible ones, and depends on context.
And even if there were no unusual evolutionary pressures on individual lineages toward greater intelligence - then it would be a random walk, starting from zero. The expected distance from the origin still grows over time.
Mammals evolve fast (I use them as the reference class here because they have encephalization about an order of magnitude higher than most nonmammals). Recent work seems to indicate that the entire diversity of mammals on Earth has a common ancestor after the KT event of 65 megayears ago. In an early fraction of that time, the diversity of mammals seems to have filled up a vast range of the possible body sizes and habitats. It would not surprise me if lineages also quickly explored most of the available encephalization ranges (ignoring weird feedback loops like those that lead to us) and the initial increase as those lineages were founded flattened on average.
Recent work seems to indicate that the entire diversity of mammals on Earth has a common ancestor after the KT event of 65 megayears ago.
Nitpick: that link talks about placentals; mammals also include monotremes and marsupials.
Increased encephalization has evolutionary costs - high energy expenditure and (in humans) difficult birth of underdeveloped infants due to head size. Natural selection will not allow encephalization beyond a certain size unless it has offsetting benefits, which depend on the species and its environment. So it's not a random walk (=neutral genetic drift) once you get far enough from the average, like we have.
If intelligence is good for every environment, we would see a trend in the encephalization quotient among all organisms as a function of time. The data does not show that. The evidence on Earth points to exactly the opposite conclusion. Earth had independent experiments in evolution thanks to continental drift. New Zealand, Madagascar, India, South America... half a dozen experiments over 10, 20, 50, even 100 million years of independent evolution did not produce anything that was more human-like than when it started. So it's a silly idea to think that species will evolve toward us.
In a word cetaceans. Some have bigger brains than humans.
The encephalization quotient that Galaxy cites isn't a direct measure of brain size, it's a ratio of actual brain mass to the value that a mammal is expected to need in order to manage things like breathing and coordinating body movements. Cetaceans and particularly dolphins do have some of the beefiest brains among mammals in terms of EQ, but humans still beat them by a wide margin.
Ants then. They are 6% brain, which easily trumps humans in terms of EQ.
The idea that there's no trend towards bigger brains seems stupid. Almost as stupid as the idea that we should expect of see such a trend in all organisms.
All modern organisms evolved from bacteria-like critters, with little nervous tissue. Of course there's a trend towards bigger brains. The only issue is why - and that seems pretty obvious too: brains pay.
A random walk away from no brain by a large number of lineages would also give you a constantly increasing upper bound on brain size.
That was S. J. Gould's model - in Life's Grandeur. Assuming that a trait like brain size behaves as though it is a neutral trait seems pretty loopy, though. Now we have enormous data centres to explain, the "random drift" model is surely no longer worth entertaining.
Ants then. They are 6% brain, which easily trumps humans in terms of EQ.
That doesn't fly either, I'm afraid. EQ is not a straight brain-to-body-mass ratio; the expected brain mass in the formula scales sublinearly against body mass, giving smaller animals a tendency to have proportionally larger brains. This is motivated by the fact that some nervous functions (diaphragm contraction, for example) are relatively constant in complexity but still have to be handled by small animals' brains, so the smaller an animal is the more nervous overhead it has to deal with.
The formula this works from was only designed to apply to mammals; different body plans have different neural requirements, and arthropod nervous systems are very different from mammalian. If we ignore that and apply the mammalian formula Ew(brain) = 0.12w(body)^0.66 to something ant-sized, it gives us an expected brain mass of about three milligrams for an ant weighing four milligrams (obviously absurd, but we knew the formula was bogus) and an encephalization quotient of about 0.08 if your 6% value is accurate. Human EQ is about 7.5.
Local minima. Dependencies between genes, other genes, and environment.
It's better to be smarter "other things being equal". But most things involve tradeoffs. The region of genetic/environmental state space where increased encephalization helps, and is likely to occur, may be very small.
It is possible that we are just the first "radio acquiring" intelligence on this planet. In this case we could expect others to evolve in the next hundred million years. Sure, if we disappear somehow without a technology left behind.
But it is also possible that we are the last as well no matter what. That our type of intelligence is just a tinny island in an ocean of possibilities.
What do you think?
[pollid:421]
What information is the poll meant to provide? The correct answer to this question doesn't depend on LWer opinion.
What information are the poll results meant to provide? The correct answer to this question doesn't depend on LWer opinion.
"The Planet-of-the-Apes Hypothesis" Revisited --Will Intelligence be a Constant in the Universe?
If intelligence is good for every environment, we would see a trend in the encephalization quotient among all organisms as a function of time. The data does not show that. The evidence on Earth points to exactly the opposite conclusion. Earth had independent experiments in evolution thanks to continental drift. New Zealand, Madagascar, India, South America... half a dozen experiments over 10, 20, 50, even 100 million years of independent evolution did not produce anything that was more human-like than when it started. So it's a silly idea to think that species will evolve toward us.