Edit: Q&A is now closed. Thanks to everyone for participating, and thanks very much to Harpending and Cochran for their responses.
In response to Kaj's review, Henry Harpending and Gregory Cochran, the authors of the The 10,000 Year Explosion, have agreed to a Q&A session with the Less Wrong community.
If you have any questions for either Harpending or Cochran, please reply to this post with a question addressed to one or both of them. Material for questions might be derived from their blog for the book which includes stories about hunting animals in Africa with an eye towards evolutionary implications (which rose to Jennifer's attention based on Steve Sailer's prior attention).
Please do not kibitz in this Q&A... instead go to the kibitzing area to talk about the Q&A session itself. Eventually, this post will be edited to note that the process has been closed, at which time there should be no new questions.
I haven't read your book yet, so forgive me if you discuss this there. But I’ve been wondering:
Simple traits (such as an organism's height) are probably relatively easy to alter via genetic mutations, without needing to combine many different genes chosen from huge populations. So, e.g., dog breeding altered dogs’ size relatively easily.
Complex adaptations aren’t nearly so easy to come by.
If intelligence is a conceptually simple thing, there might be simple mutations that create “more intelligence” -- it might be possible to make smarter people/mice/etc. by tuning a setting on an adaptation we already have. (E.g., “make more brain cells”).
If intelligence is instead something that requires many information-theoretic bits to specify, e.g. because “intelligence” is a matter of fit between an organism’s biases and the details of its environment, it shouldn’t be easy to create much more intelligence from a single mutation. (Just as if the target was a long arbitrary string in binary, and the genetic code specified that string digit by digit, simple mutations would increase fit by at most one digit.)
From the manner in which modern human intelligence evolved, what’s your guess at how simple human (or animal) intelligence is?
You are even meaner than Shulman. We don't know how human intelligence evolved and we need to know it in order to answer your question I think. This is where evolutionary psychology and differential psychology (Am I using that term right?) must come together to work this out.
We think that we know a little bit about how to raise intelligence. Just turn down the suppression of early CNS growth. If you do that in one way the eyeball grows too big and you are nearsighted, which is highly correlated with intelligence. BRCA1 is another early CNS growth suppressor, and we speculate in the book that a mildly broken BRCA1 is an IQ booster even though it gives you cancer later. BTW Greg tells me that there a high correlation between IQ and the risk of brain cancer, perhaps because of the same mechanism.
But these ways of boosting IQ are Red Green engineering. (Red Green is a popular North American comedy on television. The hero is a do-it-yourselfer who does everything shoddily.)
On the other hand IQ seems to behave like a textbook quantitative trait and it ought to respond rapidly to selection. We suggest that it did among Ashkenazi Jews and probably Parsis. IQ does not seem to have a downside in the general population, e.g. it is positively correlated with physical attractiveness, health, lifespan, and so on. Do we get insight into the costs of high IQ by looking at Ashkenazi Jews? Do they have overall higher rates of mental quirks? Cancer? I don't know.
They're engaged. :)
There is now substantial evidence that there is a causal link between prolonged focusing on close objects - of which probably the most common case is reading books (it appears that monitors are not close enough to have a substantial effect) - and nearsightedness/myopia, though this is still somewhat controversial. This is the typical explanation for the correlation between myopia and IQ and academic achievement.
A genetic explanation is possible, and would be fascinating, but I wouldn't want to accept that without further evidence. If the genetic explanation is true and environment makes no contribution, then I think one should find that IQ is more highly correlated with myopia than academic achievement -- I don't know if this has been found or not.
From The 2% Difference, an article by Robert Sapolsky:... (read more)
Do you see any difficulties for very high IQ children other than isolation?
It's a little much to expect people to have so much patience, but doing moderate IQ increases generation by generation, with large numbers of increased IQ children in each generation would do a lot to solve the social problems.
Michael Vassar is having trouble accessing this site right now, so asked me to relay this question:
You mention in your book (p. 69) that from 100,000 BC to 12,000 BC, the human population increased from half a million to six million thanks to better hunting tools and techniques. On the other hand, from page 100 onwards, you discuss Malthusian limits to population, implying that the sizes of primitive populations were proportional to the amount of food available. In other words, you seem to be saying that from 100,000 BC to 12,000 BC, the human population grew because better hunting techniques increased the availability of food.
But better hunting technologies won't generally tend to raise Malthusian limits strongly. While hunting better will mean that new prey become exploitable, it also means that old prey are continually hunted to extinction. The net result isn't a systematic trend. How strong is the evidence for any prehistoric population sizes? How do the implied population densities compare to those for other large omnivores, such as black bears and pigs, in their territories, or to the population densities at which Chimps live? Why would human densities have been much lower?
First, you have to remember that old-fashioned humans were one predator among many: improved hunting techniques could raise our share of the pot, as well as decreasing other predators' tendency to eat us. Also, modern humans seem to have used carcasses more efficiently than Neanderthals: they had permafrost storage pits and drying racks, so could have preserved meat for long periods. Neanderthals didn't, and I think they must have wasted a lot. Next, moderns used snares, traps, nets, bows etc to catch smaller game not much harvested by Neanderthals: they also made more use of fish and molluscs. And lastly, more plant foods. Altogether, their innovations gave them a larger share of the game, used that share more efficiently, tapped marine resources (lots of salmon in Europe), and harvested resources at a lower trophic level ( plants for example), which are always more abundant.
Hunting to extinction happened in some places, but not everywhere: it hardly happened in Africa at all. It happened most in places with no previous hominid occupation.
Implied population densities are, I think, e... (read more)
If a trait is being selected for, the alleles with large positive effects will compound with a faster growth rate than those with small effects (even if there are initially many more small-effect alleles) and tend to account for a large portion of the heritability of that trait (at least until they have almost swept the population).
You suggest that psychological traits such as personality and cognition have been subject to recent positive selection, so why haven't GWAS (or targeted investigations, e.g. microcephalin) found much in the way of common large effect alleles for psychological traits? What are your best guesses on the genetic architectures of personality and cognition?
Yikes! This is worse than my PhD orals.
There have been some (tentatively) identified like the 7-repeat version of the D4 dopamine receptor, the serotonin transporter, and others that Greg will be able to dredge up from his memory.
We may have found others but not identified them. Imagine that it would be highly beneficial to have a little bit less of substance s. If so then a mutation that broke the gene producing s would be favored a lot and would sweep until people with two copies of broken s started being born. How likely is it now that two broken copies of s will still work? A lot of the sweeps identified from SNP scans seem to have stalled out at intermediate frequencies (as opposed to going to fixation) suggesting that heterozygote advantage is widespread.
If so the genome wide association studies ought to find them, and they find a lot, many of the findings are not replicable. So after all the above I have no coherent answer to your question!
Do you have an overall view on the feasibility and timeline for genetic engineering of human intelligence?
For example, at what odds would you bet that we will have the ability to create hundreds of IQ +6 sigma super-geniuses by 2020 (for a reasonable cost, e.g. total project cost <$1bn)? 2030? 2040? 2050? 2075?
This is quite relevant for people interested in the singularity, because if it is highly feasible (and there are some who think it is), then it could provide a route to singularity that is independent of software AI progress, thereby forcing a rational observer to include an additional factor in favor of extreme scientific progress in the 21st century.
I would say that it is some sense obvious that higher intelligence is possible, because the process that led to whatever intelligence we have was haphazard (path-dependent, stochastic, and all that) and because what optimization did occur was under severe constraints - some of which no longer apply. Clearly, the best possible performance under severe constraints is inferior to the best possible with fewer constraints.
So, if C-sections allow baby heads to get bigger, or if calories are freely available today, changes in brain development that take advantage of those relaxed constraints ought to be feasible. In principle this does not have to result in people who are damaged or goofy, although they would not do well in ancestral environments. In practice, since we won't know what the hell we are doing... of course it will.
Still, that's too close to an existence proof: it doesn't really tell you how to do it.
You could probably get real improvements by mining existing genetic variation: look at individuals and groups with unusually high IQs, search for causal variants. Plomin and company haven't any real success ( in terms of QTLs that explain much of the variance) but f... (read more)
I don't know but I can give you some candidates. One is torsion spasm (Idiopathic Torsion Dystonia). It will give you about a ten point IQ boost just by itself. Most of the time the only effect of the disease is vulnerability to writer's cramp, but 10% of the time it puts you in a wheelchair. So you could do science just fine.
Similarly the Ashkenazi form of Gaucher's disease is not ordinarily all that serious but it also give a hefty IQ boost. Asperger like stuff would probably also increase: many super bright people seem to be a bit not quite. Of course lots of other super-brights seem to be completely normal.
I am just babbling, I have no special insight at all...
The Neanderthal genomics work showing a few percent of non-African human genomes inherited from Neanderthals suggests that any individual handy Neanderthal alleles would have needed only a few doublings to reach fixation. Any news on whether the Neanderthal variants show more or less post-mixture selection than you would have expected?
No word on that yet. They identified regions of the genome where there are (1) deep gene trees in Europe and/or Asia, (2) we share variants with Neanderthals, and (3) these shared variants are absent in Africa, and they found a lot of them. But if some variants in Neanderthals were positively selected in humans very early on then they would have spread through all humanity, and no one has scanned for those yet.
Our favorite candidate is the famous FOXP2 region, without which one has no speech. Every human has it, and the diversity hear it on the chromosome suggests that it is 42,000 years old in humans. Neanderthals have the human version (so far), so a likely scenario is that we stole it from Neanderthals.
Paabo seems to think it unlikely that any of these introgressed alleles had a a significant selective advantage in humans, but that's unlikely. I'll bet money on this.
To be fair, I should explain why that is a sucker bet. John Hawks and I discussed about a situation with just a few tens of matings over all time: we were making the point that even in that minimal scenario, alleles with large advantages (on the order of 5%) could jump over to modern humans. The Max Planck estimate of 2% Neanderthal admixture is far more favorable to introgression: with that much of a start, and with at least 50,000 years to grow in, any allele with a selective advantage > 0.2% is likely to be over 50% today. Many such Neanderthal alleles should be fixed in Eurasians - or in some Eurasian populations in the right environments - or even in Africans, if the allele conferred global advantages. of course we'd have trouble proving this in Africans: the Science study really shows how much more Neanderthal ancestry Eurasians have than Africans, not the absolute amount in either population.
Note that the Fisher-wave velocity goes as the square root of the selective advantage: a Neanderthal allele with an... (read more)
What are your thoughts on the Flynn effect?
When I did fieldwork in the late 1960s in backcountry Botswana I hit upon the idea of asking my sister (a dairy farmer) to send me a box of back issues of American cattle magazines. It was unbelievable: I could have made a fortune selling pictures from them, not to mention whole issues, to the local cattle people. At that time people carefully hoarded little scraps of paper to use writing messages.
In the late 1980s I brought some more such magazines with me, and no one was interested at all. The media storm had penetrated and everyone had school textbooks, magazines, radios, etc.
I have the same impression, though it could be partly due to the growth and specialization in the pop-culture market, so that the sample you happen to see today is mainly from the output targeted at smarter audiences. But the difference seems too large to explain just by that effect; the old shows are often truly mind-numbingly dull, as you describe. There was a post about this topic a few years ago on Marginal Revolution with some striking diagrams: http://www.marginalrevolution.com/marginalrevolution/2005/04/tv_and_the_flyn.html
What makes it even more puzzling is that these apparent huge increases in average folks' sharpness were not accompanied by anything similar at the higher levels of intellectual accomplishment. In many countries, a teacher or professor who taught for, say, 30 years during the se... (read more)
This study (which HughRistik originally pointed to here) suggests that IQ distribution might be better modeled as two overlapping normal distributions, one for people who are not suffering from any conditions disrupting normal intelligence development (such as disease, nutritional problems, maternal drug or alcohol use during pregnancy, etc.) and the other for those who suffered developmental impairment. If this model has some validity the Flynn effect could perhaps be explained as a reduction in the number of people falling into the 'impaired' distribution due to improved health and nutrition in the population. This would seem to explain an increase in the average score without a corresponding increase in the number of 'geniuses'.
The discussion's been going on for a while and it's been slowing down, so I think it's time to close down the official Q&A session. Henry and Gregory, you're of course still free to check the post and write comments if you want to, but there's no "official" expectation for that. Of course, you're also free to familiarize yourself with the rest of the site, if you think it's interesting enough, but that's entirely up to you. :)
I would like to take the chance to thank you for your excellent answers. There was a lot of interesting stuff in there... (read more)
The mathematical models for an acceleration of human evolution seem like they could have been developed earlier. Would more researchers, or more 'maverick' researchers have much advanced progress in the field? Or would an increased stock of mathematical analysis have simply sat around unused until the advent of the new genomics tools and their ability to measure selection?
That is a big and interesting question. I do not think that evolutionary biology needed more math at all: they would have done better with less I think. The only math needed (so far) in thinking about acceleration is the result that the fixation probability of a new mutant is 1/2N if it is neutral and 2s if it has selective advantage s. The other important equation is that the change in a quantitative trait is the product of the heritability and the selective differential (the difference between the mean of the population and the mean of parents).
The history is that there was a ruckus in the 1960s between the selectionists and the new sect of neutralism, and neutralism more or less won. Selectionists persisted but that literature has a focus on bacteria in chemostats, plants, yeast, and such. Neutralism answered lots of questions and is associated with some lovely math, but as we took it up we (many of us) lost sight of real evolutionary issues.
Milford Wolpoff, in a review of our book in the American Journal of Physical Anthropology points out that his student Dave Frayer collected a lot of data on changes in European skull size and shape that implied very rapid evolution. In other words we "knew it all along" but never paid attention. In fact Cochran and I "knew" it but never put it together with the new findings from SNP chips. John Hawks did, right away.
So fashion rules and we it is difficult to get away from it I suppose.
Hawks and I were talking about new genetic studies that showed a surprising number of sweeps, more than you'd expect from the long-term rate of change - and simultaneously noticed that there sure are a lot more people then there used to be - all potential mutants.
As for why someone didn't point this out earlier - say in 1930, when key results were available - I blame bad traditions in biology. Biologists mostly don't believe in theory: even when its predictions come true, they're not impressed.
My advantage, at least in part, comes from have had exactly one biology course in my entire life, which I took in the summer of my freshman year of high school, in a successful effort to avoid dissecting. If I ever write a scientific autobiography, it will be titled "Avoiding the Frog".
I think Greg's 'biologists' are a special subset of biologists. As I see it CP Snow was right about the two cultures. But within science there are also two cultures, one of whom speaks mathematics and the other that speaks organic chemistry. Speaker of organic chemistry share a view that enough lab work and enough data will answer all the questions. They don't need no silly equations.
In our field the folks who speak mathematics tend to view the lab rats as glorified techs. This is certain not right but it is there and leads to a certain amount of mutual disdain.
This kind of mutual disdain is apparently just not there in physics between the theoretical and experimental physics people. I wish evolutionary biology were more like physics.
[I waited until I could get a copy of the book and read it before making my point here.]
In the book you say that foragers had little reason to fight wars or to to be patient for long term investments. But forager wars are often about grabbing women, and they might also make long term investments in particular women or in developing skills, like singing, that can attract women.
I don't agree with you except a little bit. And there are foragers who do have some low time preference, like on the US Northwest Coast where they harvested lots of salmon that they smoked and stored. Interior Eskimo slaughtered migrating caribou herds and stored the meat by freezing.
But in general forager life has been almost literally hand to mouth. I have spent a lot of wasted time pulling my hair out about this. We have had lots of Bushman employees in the Kalahari, well compensated. We have spent hours pointing out that we would go back to America, they should invest in goats or cattle, build up a herd, so they will have something to live on after we left. Everyone agreed with us, but they minute Aunt Nellie got sick everything was slaughtered. Again and again and again. Aargghh......
I thought RichardKennaway's previous comment was interesting, and would appreciate hearing your comments on it. Commenting on the hypothesis that life under the rule of others may have selected for submissiveness, he wrote:
My feeling is that the dichotomy between societies where males are threatening and violent and societies where males are submissive and not threats to each other is the most interesting social dichotomy we have. In some societies where males are threats there is a clear alternative niche like the Berdache on the Great Plains. In urban ghettos with drug dealers and street corner males there is a significant set of males who hold down jobs and, often, bring the proceeds to support their matrifocal families. How much such males reproduce is not clear. A wonderful description of this, with a zany analysis, is (Sharff, J. W. (1981). Free enterprise and the ghetto family. Psychology Today, 15, 41-8.)
There may well be stable distributions lurking in the social system but they are likely different everywhere: that for Bushmen would be quite different from that for Mundurucu.
Rulers do not always leave more descendants than proles. I highly recommend Gregory Clark's "Farewell to Alms", in which he shows that the medieval ruling class in Britain essentially all killed each other and have no descendants today. On the other end peasants and laborers did not reproduce themselves, so almost everyone in the UK today is descended from the medieval gentry, prosperous merchants, and so on.
When I think of evolutionary psychology I generally jump to sharp and well defined claims that "mental modules" exist that (1) enable superior cognitive performance in specific domains relative to what typical people can do when they rely on "general reasoning" faculties, (2) evolved due to positive selection on our ancestors to deal with problems we faced over and over in our evolutionary history, and (3) should be pretty much universal among humans who don't have too many deleterious mutations.
When I think of people who focus specific... (read more)
For both/either: What are you working on right now?
I have always been curious about the effects of mass-death on human genetics. Is large scale death from plague, war, or natural-disaster likely to have much effect on the genetics of cognitive architecture, or are outcomes generally too random? Is there evidence for what traits are selected for by these events?
Wow! I haven't got any questions (yet) but I am very eager to dive into this Q&A. Thanks to everyone involved in organizing this.
By the way, you spelled Steve SailEr's name wrong.