By Frank Remele
I was reading the 10,000 Year Explosion by Greg Cochran and the late Henry Harpending. The thesis of the book, that culture accelerated evolution, was bewilderingly obvious to me. This is the case because of new selective pressures, or environments that a population needs to adapt to. I should clarify that I say this without a hint of arrogance, as I mean only that the notion of human evolution ceasing when we ventured out of Africa seems totally arbitrary. Moreover, if human culture shaped the environments we were in, and vice versa, there’s no reason to believe selective pressures wouldn’t emerge. You don’t need empirical data to envision these pressures. It makes sense intuitively. There’s a lion pride in Africa. Mass starvation in that ecosystem occurs. The smallest lions do the best—they don’t need so much food. So why does it matter that it’s [bewilderingly] obvious? Well, it lends an explanation for the book. There is no reasonable explanation for an exposition of the obvious, unless there is an audience that opposes it. Well-intentioned scientists refrain from evading the truth often write their popsci books in two parts: the first is effectively data, and the second are societal implications. It might sound foreboding: a book on the innate qualities of certain traits, and differences among populations in those traits, complete with an afterword about what this means for culture. Quite typically, however, the afterword is a piece on how to either reduce those differences, or how to live in a manner that effectively ignores (or accommodates) them. I can go on and on about my own speculation, but a lot aligns very closely with issues addressed in Steven Pinker’s The Blank Slate. This post was not intended to be one that deviates much away from the raw science, but I will say this: some people get worked up over the smallest things. And of those, many fight tooth and nail to rid of the “concept” of innate biological traits – height! That is why books like The 10,000 Year Explosion and The Blank Slate are not unnecessary.
The most fascinating event on the anthropological timeline is The Upper Paleolithic Revolution. At this time period, we see traits emerge that are precursors to culture: language, permanent settlements, and art. Anatomically modern humans had arrived long before, but now we begin to see behaviorally modern humans. Overwhelmingly, scientists argue that this change in behaviour was abrupt—very abrupt. Coherently, researchers suggest a genetic basis for this change, say, the FOXP2 gene. It isn’t clear yet what the specific change is, only that it’s fairly obviously biological in nature. However, not to some people, it seems. Some scientists point to tools that predate the putative timeframe for the Upper Paleolithic Revolution, as if that’s evidence for some sort of gradualistic development towards the era we call a “revolution.”
Here’s why it isn’t. The tools that start propagating during the UPR—tools we can actually call modern—are task-specific, discernibly so. The “tools” that gradualists use to suggest their case is correct could be used for anything, in the same way clay works. That doesn’t make them better; quite the contrary, in fact. They are tools only in that they are marginally more effective than bare hands at completing something. Any fool can take a rock and hit someone in the kisser with it: it just won’t be effective as a bow and arrow will.
If we know that the event we call a revolution really was just that, what sort of genetic phenomenon might have occurred? Major selective pressures? I don’t think so. Environmental change would have to be significant, far more significant than I can envision, and far more significant than archaeological records might indicate. If they did, we’d have our answer. Did the food supply suddenly become contingent on passing your calculus exams? I doubt it, unless Giorgio Tsoukalos of Ancient Aliens is correct in that aliens were the guiding influence of human culture. (You wouldn’t be in bad company if you believed it. The History Channel endorses it.) Greg Cochran and the late Henry Harpending believed that introgression was behind the UPR. Specifically, human-Neanderthal mating. In the 10,000 Years Explosion they address the anticipated reaction to this hypothesis: one of skepticism, scorn, and downright disgust. See here: “Many object to the notion of humans and Neanderthals mating and having offspring. Their first impulse is to suggest that anatomically modern humans and Neanderthals must have been too different, so that matings would not have produced fertile offspring. They say that humans would never have done such a disgusting thing. And they say that even if it happened, it was almost certainly rare, and thus biologically insignificant. None of these claims are correct: We will address them all.” Personally, I don’t really care, nor am I surprised. Because in some broad sense, race really is a social construct. This isn’t said with a revisionist leftist undertone; rather, it is the observation that races mixing makes the whole concept of race a little more dubious. Humans 40,000 years ago may very well have seen the Neanderthals merely as a different race.
Contributing to the disgust factor of this hypothesis might be that Neanderthals are household staples for jokes pertaining to intelligence (or lack of.) Does this idea have any scientific basis? The authors aren’t entirely sure. From chapter two, The Neanderthal Within: “Another idea is that modern humans were smarter—which might have been the case, but it is hard to prove.” Therefore, it might be possible, but the evidence isn’t crystal clear, and that doesn’t confer the stereotype that we’re all familiar with today. It begs the question: if it isn’t intelligence that was transferred as a product of introgression, then what advantageous allele(s) were? Perhaps a language gene. They make the case that the reason a language gene in Neanderthals didn’t yield similar cultural results is because it would not have been as revolutionary in comparison to a more advanced species that might make more use of it. Fair enough, but what genetic evidence do we have for it? Researchers Jeffrey Wall and Vincent Plagnol determined that five percent of genetic variation in Sub-Saharan Africans and Europeans originated in ancient humans (Neanderthals?). Cochran and Harpending argue that this prevalence in both groups would occur only if the allele had strikingly advantageous effects. A point is made that although inbreeding did occur, it was relatively rare, so the allele had to have spread on its own terms, through natural selection. Makes sense.
We have the general hypothesis laid out regarding the origins of the Upper Paleolithic Revolution. However, the book was published in 2009, and given the nature of the field (Cochran mentioned this recently in his West Hunter blog) there are claims that can be either proven or disproven. The authors asserted that the introgression was from Neanderthals specifically, unlike the claims that Wall and Plagnol make (broadly archaic human). Lucky them. Benjamin Vernot and Joshua M. Akey from the University of Washington found that more than twenty percent of the Neanderthal genome persists in individuals from Europe and Asia. Of course, sub-Saharan Africans aren’t mentioned, but I’d wager that has more to do with the sampling rather than whether or not those alleles actually persist. At any rate, I should clarify that I’d be doing a massive disservice to the authors by saying “lucky them.” Science is characterized by prediction and verification, and when the predictions don’t play out in reality it isn’t necessarily a bad thing. But when they are correct—well, let’s just say you can still be damn good at gambling.
Citations:
- Klein, Richard (1995). “Anatomy, behavior, and modern human origins”. Journal of World Prehistory. 9: 167–198. doi:10.1007/bf02221838.
- attersall, Ian (2009). “Human origins: Out of Africa”. PNAS. 106 (38): 16018–16021. Bibcode:2009PNAS..10616018T. doi:10.1073/pnas.0903207106.
- Plagnol V, Wall JD (2006) Possible Ancestral Structure in Human Populations. PLoS Genet 2(7): e105. https://doi.org/10.1371/journal.pgen.0020105
- Benjamin Vernot and Joshua M. Akey. Resurrecting Surviving Neandertal Lineages from Modern Human Genomes. Science, 29 January 2014 DOI: 10.1126/science.1245938