The 10,000 Year Explosion: How Civilization Accelerated Human Evolution

This book, published in 2009, was written by Gregory Cochran and Henry Harpending, two of the authors of the study of intelligence among Ashkenazi Jews cited earlier. It is an expansion of the ideas behind that hypothesis and attempts to show that human evolution is ongoing and did not, as many believe, stop about 40,000 years ago. They argue that the rate of evolutionary change in humans has increased since the end of the last ice age, about 10,000 years ago, and that this change has been driven primarily by the shift from a hunter-gatherer subsistence to an agricultural subsistence. Although I find most of their arguments persuasive, their placement of biology ahead of culture as an explanation for certain human characteristics has caused them to be labeled as racists by some. The book was not widely reviewed, but still seems to have developed somewhat of a cult following. Generally, it is consistent with many of the positions that I've taken in this blog, and I consider it to be an admirable effort to place scientific investigation ahead of unfounded academic ideology, though it may prove to be incorrect in some respects. I'll summarize it and then comment broadly on the detractors of this kind of thinking and how their objections may be resolved.

Several pages are devoted to the Neanderthals, who were, as of the time of writing, suspected of interbreeding with the first wave of humans to enter Europe. Since the book was written, that has been confirmed, with some modern humans inheriting and retaining immunity genes from Neanderthals, which is consistent with the theorizing of the authors. In general, it is becoming increasingly possible to study such matters with the help of advances in molecular biology. The heart of the book concerns the development of agriculture, which the authors believe created new evolutionary pressures among humans. On the one hand, food became more consistently available, but on the other hand farming made certain new abilities and skills advantageous. Previously, hunter-gatherers had little use for private property and escaped contact with many diseases through their nomadic existence. Because farming made them stationary, their populations grew and their proximity to livestock exposed them to new diseases, the authors speculate that immunity to disease became an important biological adaptation. Furthermore, humans were pressured to develop systems for the protection of private property, since their immobility made them more vulnerable to the theft of their food supplies. Eventually, as agricultural systems became prevalent, civilization led to governments and record-keeping. In the authors' view, genetic changes emerged during the process.

The principal example of genetic change cited is the development of lactose tolerance, which occurred more than once during this period. With a constant supply of digestible dairy milk, it became possible for populations to increase dramatically in size during a short period of time. Once large, concentrated populations came into being, it became possible for more mutations to occur over shorter periods of time, and new alleles which conferred greater fitness spread rapidly. Much of the book describes real-world genetics and gene flow. The analysis contrasts with ones such as that of Jared Diamond, who argued in Guns, Germs and Steel that cultural changes associated with food production gave those groups an advantage over other groups. Cochran and Harpending believe that natural selection occurred, that there is a genetic basis for the changes and that since then there has been a change in cognition and personality traits that conferred an advantage to those groups. Specifically, they claim that the people who first transitioned away from a nomadic life had an advantage which eventually led them to develop modern science and to initiate the Industrial Revolution. While their view can be interpreted as racist, they present it as a scientific hypothesis that has conceptual merit in its own right. They believe that the societies which practiced agriculture for the longest periods became genetically different from societies which adopted agriculture later on. As they explain:

Human evolution didn't stop when anatomically modern humans appeared, or when they expanded out of Africa. It never stopped – and why would it? Evolutionary stasis requires a static environment, whereas behavioral modernity is all about innovation and change. Stability is exactly what we have not had. That should be obvious, but instead the human sciences have labored under the strange idea that evolution stopped 40,000 years ago.

When it comes to identifying the actual groups that underwent this evolution, the book is a little unclear. The authors posit the main group as the one that first adopted the Indo-European language, also known as the Proto-Indo-Europeans. They are even murkier when it comes to identifying the actual alleles that behaviorally differentiated them from other humans. The most specific example of recent evolution offered is the one concerning inherited intelligence among Ashkenazi Jews, and though they associate this with alleles related to certain diseases, they are short on proof. However, this writing is primarily of a theoretical nature and serves mainly as a guide to future research.

On some fronts Cochran and Harpending have been attacked as racists. Cochran is probably safe professionally, since he is a self-employed physicist. Harpending was a professor in the Anthropology Department at the University of Utah and died last year from a stroke. However, they have received some positive recognition, and Steven Pinker, the cognitive scientist, supports their theory of Ashkenazim intelligence. Although I am ideologically neutral, I am shocked by the extent to which political correctness has infiltrated the world of American intellectuals. Stephen Jay Gould, the well-known paleontologist and evolutionary biologist, argued, incorrectly in the view of the authors, that human evolution could not have occurred since humans left Africa, because that was too short a time span. He also went overboard in discrediting IQ tests, which, though imperfect, do have some use and have shown that intelligence is more the result of inheritance than cultural environment. Another offender has been the evolutionary biologist Richard Lewontin, who argued against sociobiology and popularized the idea that 85 per cent of human genetic variation occurs within groups as compared to 15 percent between groups, supporting the idea that all modern humans are basically the same. On this, Cochran and Harpending say:

Using the same reasoning that Lewontin applied in his argument about human populations, one would have to conclude that differences between individual Great Danes must be greater than the average difference between Great Danes and Chihuahuas.

Lewontin may technically be correct if you count all genes, but there is a lot of junk to be found in genes, and it is misleading to lump in the critical genes of an organism with ones that serve no known function. Gould and Lewontin represent the liberal dogma that is still prevalent at the New York Review of Books.

Not being a scientist, my views are the result mainly of lifelong observation. On that basis it has been obvious to me that heritable intelligence is a real phenomenon that cannot be ascribed entirely to environmental influences. Thus I agree with Cochran and Harpending that Ashkenazi Jews received a boost in intelligence through natural selection. Other aspects of their argument are too vague for confirmation anytime soon. Although there is probably something to it, we're nowhere near finding anything that would resemble the genes for complex behavior such as "the Puritan work ethic," which Cochran and Harpending seem to think constitutes a recent evolutionary development. In my view there are many real differences between individuals, and no amount of politically correct indoctrination is about to convince me otherwise. To some extent the movement to consider all people the same has a desirable side, in that it might potentially reduce conflict. However, to the extent that it ignores reality it is anti-scientific and encourages delusional thinking. It also has a theological quality which I find offensive. My own preference is to think in terms of eusociality and law and to emphasize legal equality over biological sameness. The meme that is currently circulating in favor of equality seems to deny the possibility that significant biological differences can exist between groups, and there are costs to such misunderstandings. The most obvious ones pertain to public policies such as the use of education to foster economic equality among all groups. The fact is that, for biological reasons, not all groups are going to be able to produce the same percentage of rocket scientists as the Ashkenazi Jews no matter how well-educated they become. If you fully buy into the arguments of Cochran and Harpending, you may also want to look at some world conflicts as having causes related to differences between populations that have long agricultural histories and those that have maintained nomadic or pastoral practices until recently. Whether or not such speculations are fruitful, they would certainly be more mind-expanding than the dogmatic clichés repeated perpetually in politically correct circles.

Much of the rancor that surfaces whenever there is a hint of racism or bigotry relates to the perception that one group is being considered inferior to another. My view is that, given the sloppy, random process of evolution and the general limitations of human beings as organisms, such thinking is a waste of time. It is true that some people have cognitive skills that enable them to perform tasks that others can't and that other people have other skills that are lacking in intelligent people, but there is no point to arranging everyone into a meaningless hierarchy. From a policy standpoint the only thing that is important is that people are treated equally under the law, and there is no reason to pretend that all people would have identical abilities under the right circumstances. In my futurist frame of mind I like to think that what is currently seen as high intelligence will someday be seen as a small differentiation compared to what becomes available through AI. As an exercise, I entertain myself by thinking of apps such as ones that decide which career suits you, which colleges you apply to, whom you marry, where you live, whom you vote for and which hobbies you adopt. There is no reason to think that such apps couldn't do a better job than people have been doing without them up to now. In this framework humans become simple inhabitants of the universe rather than exalted beings worthy of awe, and I find that preferable to the petty posturing and one-upmanship that seems to dominate contemporary life.