Who We Are and How We Got Here: Ancient DNA and the New Science of the Human Past (David Reich)

We have all heard of the fad for DNA ancestry testing. Being a paranoid, I haven’t joined the crowd, because all testing companies are happy to hand over the results to the police, and what if I need to keep quiet some heinous crime I commit where I leave my DNA behind? Not to mention, what those tests claim to reveal about you is limited, in many cases, by inadequate comparison data, which the companies fill in with lies. But that lack of comparison data is swiftly being remedied, both in the present, and in the past, which is the topic of this book.

David Reich is a prominent scientist in the field of ancient DNA. This means that he and his colleagues collect DNA from skeletons around the world and then slice-and-dice the data to figure who moved where from where in prehistory—and to divide people into identifiable and distinguishable groups. It is this latter enterprise that is fraught with political peril, since if groups of humans are distinguishable on a genetic basis, then it may appear that we are not all one big happy human family. Reich therefore threads the needle, with mixed success. He has no doubt that groups of humans differ in many important ways—but those aren’t necessarily the ways we think. His key point in the entire book is that all human populations are mixtures, frequently of groups we would not expect, and so theories based on the supposed historical purity of an ethnic group are inherently silly. Whether that keeps him out of controversy, we will see in this review.

Reich begins with a fairly detailed description of the history and practice of DNA testing of samples from dead people. Nobody will ever accuse Reich of sparkling prose, but he competently transmits to the reader the relevant information, which is very interesting if you pay attention. Numerous very well-done maps and other visual aids complement the dense text. This science is surprisingly recent—all in the past ten years, and most of it in the past five. Thus, one of Reich’s frequently repeated points is how fast the field is changing and how the amount of data available is exponentially increasing. This does not change his conclusions, but does suggest that refinement and ever-more-narrow focus will be possible when examining human history through DNA (and, of course, that commercial DNA testing of live people will be more accurate in its results).

True, the author overstates the importance of his own project, which vanity is natural, I suppose. He tells us that grasping the precise differences between Neanderthals and humans, for example, will “take an evolutionary Manhattan Project.” That doesn’t sound like a great use of resources, since last I looked into it the Neanderthals had all checked out. But Reich instead concludes “This Manhattan Project of human evolutionary biology is one to which we as a species should commit ourselves. . . . I expect that the findings will be so complicated . . . that few people will find the answer comprehensible.” Still, this “scientific question is profoundly important.” Why? Beats me. Reich doesn’t tell us.

Anyway, the key scientific point is that all DNA contains mutations, and by comparing the resulting differences in sequences of DNA, it is possible both to group human populations and to roughly calculate at which point they diverged from a common ancestor. By this means a type of family tree can be constructed. Thus, for example, it is relatively easy to show not only that populations in Africa diverged from populations outside Africa about 50,000 years ago (the “out of Africa” hypothesis, now proven), but also that those outside passed through a “population bottleneck” reducing diversity, while populations in Africa never faced such a bottleneck, and therefore have more genetic diversity. (Actually, there were multiple bottlenecks—the Finns, for example, are subject to a variety of unique genetic diseases, since all are descended from two men about 3,000 years ago.) Tree, though, according to Reich, is the wrong metaphor. It is more like a trellis, as human populations combined and recombined over time, creating a tangled web of ancestry.

Reich spends quite a bit of time on how we became human—that is, homo sapiens as opposed to homo neanderthalensis or one of the other proto-human lineages. The common perception is that that there was a magic switch, perhaps not due to a large black alien monolith, but still some sudden change that enabled human language and tool usage, distinguishing us not only from animals, but from all our ancestors. Although this is not a focus of his book, Reich says that this is unlikely, since the most recent shared common ancestor of all modern humans was about 320,000 years ago, and the “switch” was about 70,000 years ago. Thus, different groups must have “switched” independently. As Reich points out, while groups of humans differ predictably and genetically on many traits, from eye color to height, it has become clear that in most cases a large number of genes each contribute to each trait, suggesting that a simple tale of natural selection for a particular gene is not accurate (although it is for some traits, such as selection for lactose tolerance). For that reason, at least as far as we can tell, there is no one single gene that enabled us to leap beyond all our ancestors.

Since everybody wants to know, Reich talks about sex with Neanderthals. Yes, they interbred with humans. Not all humans. Reich claims that “non-African genomes today are around 1.5 to 2.1 percent Neanderthal in origin,” a percentage that has declined linearly over time, something Reich attributes in part to hybrids potentially having reduced fertility. (African genomes contain zero Neanderthal genes, since only the populations that left Africa interacted with the Neanderthals.) The Neanderthals weren’t the only “archaic humans,” though. DNA has shown evidence of more, including the Denisovans (from DNA found in Russia) and the Flores Island “hobbits.” (And I see in the news today that an entirely new one was just discovered in the Philippines). Again, the lineage of these other archaic humans can be traced—those modern humans with the most Denisovan ancestry, for example, are found only in New Guinea, the same place where modern humans have the most Neanderthal ancestry, as it happens. In some ways this is the tip of the iceberg, because, Reich tells us, the DNA data shows evidence of “ghost populations”—precursor archaic populations of whom no skeletons have been found, even farther back in the human family tree. The evidence suggests it is possible, for example, that humans left Africa more than a million years ago, and sometime before 300,000 years ago returned to Africa, then left again in the migration we are more familiar with. Reich is certain this and many other puzzles will soon be solved, and he’s probably right.

In all his analysis, Reich doesn’t rely only on DNA, fortunately—he ties in other archaeological data, and to the extent feasible, linguistic data. At the same time, he gives DNA primacy, gleefully pointing out various instances in which, he says, DNA has overturned received wisdom based on archaeology. Among these are the destruction of Nicholas Dirks’s claim that caste endogamy in India was a creation of British rule. Instead, the DNA shows ultra-strict caste endogamy, even within very narrow caste subgroups, has existed for thousands of years (although, naturally, Reich feels he has to virtue signal, noting “I find restrictions on marriage discomfiting,” even though nobody asked him, and nobody cares what his personal opinions are).

Reich focuses a good deal on Eurasia, trying to trace the movements of peoples, and in particular focusing on the relationship of farming to different identifiable groups, noting that farming spread in part by groups replacing other groups, and partially by cultural transmission or local invention. In Europe, populations were repeatedly swept aside by others—for example, the genetics embodied by the builders of Stonehenge, around 3500 B.C., were within a thousand years nearly totally replaced by those with Eurasian steppe ancestry, the Bell Beaker people. And somewhat later, the Corded Ware people, both a culture and an identifiable genetic group, came from the steppes and replaced much of the European population in the second millennium B.C.

This question of the relative importance of replacement and cultural transmission in the movement of technology is fraught, since ever since the nineteenth century brought us scientific racism, various proponents of racial purity have claimed that their ancestors replaced inferior peoples, as shown by the spread of technology, and therefore they are better and more deserving. Reich notes that the reaction to this line of thought has improperly elevated the importance of mere cultural transmission, or, put more accurately, politicized science and eroded its reliability. And, in fact, he says that German co-authors on papers of his have resigned as authors, afraid that the DNA evidence supports German racial theorists (pre-Nazi ones, but still).

For all the fascination in this, Reich loses the plot when he tries to stretch his narrative beyond his competence. Some of this is simple political correctness—Reich consistently uses the annoying and inaccurate term “Native American” instead of the more accurate, and normally used in anthropology (at least until recently—I’m not sure now), term of “American Indian.” Reich kowtows to the ideology behind this propaganda repeatedly, probably because Indian tribal demands to veto harvesting and use of genetic data are a real problem for him getting the data he wants. Thus, we get abasement like “There is also an awareness that some scientists have studied Native Americans to learn about questions of interest primarily to non-Native Americans, without paying attention to the interests of Native Americans themselves.” Well, yes. Why would it be different? On the other hand, when your studies involve tearing apart the skeletons of a tribe’s ancestors so you can get at the richest source of DNA, a bone in the inner ear, I have a lot of sympathy for horrified Indian elders. We also get dumb statements like “the last five hundred years have witnessed repeated cases in which people of European ancestry have exploited the indigenous peoples of the Americas using the toolkit of Western science.” I’m not sure what those “cases” are, since none are named, though perhaps by “exploiting” he means the West blessing the natives with our toolkit of antibiotics and anesthetics.

Reich also offers examples, fortunately only a few, of atrocious history. Most notably, he repeatedly cites the totally discredited 1950s anthropologist Marija Gimbutas, whose fantasy of a wholly imaginary female-led, pacifist early European culture is the stuff of comedy. (Among other silliness, she claimed that images of young girls and bulls in Minoan Crete depicted a game where happy girls jumped over bulls as part of their training in the matriarchy. What they actually showed, as real archaeologists proved, was virgins being sacrificed by being thrown to wild bulls.) Gimbutas also believed that Neolithic Eurasian cultures were peaceful, another joke disproven by Lawrence Keeley in War Before Civilization, although weirdly, still desperately believed by many. None of this really detracts from the book, but when Reich sticks to hard science, his book is a lot better.

No doubt mixtures are what all humans are. Reich makes that very clear, with no wiggle room. What causes Reich his first problem is how those mixtures came about. Namely, often by conquest, and his data repeatedly confirms legends of conquest, most notably in the subjugation of the Dravidic peoples of India by people from the North, just as the Rig Veda claims. Reich tries to soften this, aware of the Nazi focus on the spread of Indo-European language by “Aryans,” and the current conflicts in India over these matters, but the facts are what the facts are, and those line up with the legends. Trying to avoid the hate patrol, he says “we groped toward a formulation that would be scientifically accurate as well as sensitive to these issues” of “cultural resonance.” Ha ha. Nicely put. So they slapped fresh labels on the relevant people, calling the invaders “Ancestral North Indians” and the conquered people “Ancestral South Indians,” said they were all mixed up in the modern era, and called it a day.

Ah, but how did they get “all mixed up”? That’s where Reich’s second problem shows up. This, not discredited racial theories of pure group descent, is where Reich gets himself tied in knots. It’s easy enough to disprove racial theories, or rather racial group origin theories, since it’s now easy to prove that human populations repeatedly mix, and as I say Reich does so, covering all the continents. But the mixing isn’t uniform. Reich is just shocked, shocked, to find that two things are true. First, when populations mix, usually a very small number of men from Population A, the invaders, have the most children. Second, the women of Population B all give it up only to men from Population A, so the genetic material of the men of Population B mostly disappears. This is true, among other places, in India, Latin America, and among descendants of those conquered by the Mongols. Who could have guessed? Not Reich, who maunders on and on about how this shows “inequality” and that most dread of maladies, “sexual dominance.” He also name-checks “sex bias” and “sexual inequality.” Welcome to the real world, where absent an opposing moral code biology dictates human action and strong men get the women, many and often. This isn’t a “genetic scar,” it’s how the world works. And it’s a bit much for a geneticist to demand “struggle” against the “demon” of “sexual inequality” because it is an “ennobling behavior”; it may be, but on what basis an atheist materialist like Reich claims that, I have no idea. (Looking at Reich’s picture, one imagines that he doesn’t think he’d come out among Population A’s winning alpha males, which may account for his snippy reaction to reality. Unlike me—I look like the Kurgan in Highlander.)

And for his pièce de résistance, Reich faces, but then tries to slip by, his biggest problem. That is that racial mixing doesn’t obviate his other finding, that as of today there are distinct populations, by which Reich means “races,” and those populations have very different genetic characteristics. He admits that to say “race is a social construct” is just a total falsehood, and the work of people like Richard Lewontin purporting to show that groups cannot be legitimately distinguished has been totally falsified. The logical next question is what the differences mean for the perceptible characteristics of those populations. Some are merely cosmetic, but are there others? Certainly there are—Reich himself notes many, such as height, tolerance of high altitudes, and so forth. How about others, such as general intelligence?

This is the third rail of genetic research, though, understandably. True, the modern groups discerned by DNA testing don’t line up with the old racial groupings, or at least not completely, due to the extensive mixing in relatively recent history that Reich documents. But the visceral reaction against these types of claims usually prevents any admission of them. It even prevents wholly legitimate medical research that might be of profound help to some population groups. Reich narrates various demands to censor his and others’ genetic research, among other things citing a Northwestern political scientist who is demanding that Congress pass a law banning the publication of any federally-funded research (i.e., almost all of it) that even mentions “genetics associated with variables of race, ethnicity, nationality, or any other category of population that is observed or imagined as heritable.”

I personally find it of little importance or interest if different races differ as to intelligence, though no doubt general intelligence correlates with individual success in the modern world. Like Thomas Sowell, I suppose I’m open to the idea that different races have different characteristics such as intelligence; I just don’t care that much. First, I do not think a flourishing society can take an instrumentalist view of human beings, reducing them to their capacities on a set of defined traits. I therefore agree with Reich that whatever the differences, “If we aspire to treat all individuals with respect regardless of the extraordinary differences that exist among individuals within a population, it should not be so much more of an effort to accommodate the smaller but still significant average differences among populations.” The flaw in applying Reich’s reasoning, though, is that it doesn’t appeal to our modern society, which is inherently instrumentalist, since it has abandoned any coherent moral code at the same time it abandoned religion. I also agree with Reich that every person should be given “every chance to succeed”—although that does imply that some groups will then potentially succeed at greater rates than others. In practice, then, it becomes a question of what, if anything, is to be done to alleviate inequalities across groups potentially resulting from genetic differences.

Second, as to any given society, even if the average intelligence of that society were found to be lower than another, for whatever reason, it would still have enough highly intelligent people to run the society as well as any human society has ever been run—if the society has the right culture, able to get everyone, even the less intelligent or less able on whatever measure is relevant, to pull the society along together. Unfortunately, most cultures in human history have been pretty crap, a few have been mediocre, and only one, the Christendom of the West, has ever been excellent (and it’s mostly gone now, with the West now running on fumes, so those in Europe complaining about Muslims swamping Europe are, in large part, barking up the wrong tree).

Reich, though, flails. He tries to establish his “I’m not a racist” bona fides by attacking Nicholas Wade, the only major popular author in recent years to suggest that heritable genetic characteristics created the success of the West, in part by correlation of desirable genetic traits to “Caucasians.” Wade’s is a pretty mild point, in essence that superior social institutions were the result of small genetic differences, and those social institutions made the difference, which is impossible to argue, though the origin of superior social institutions is open to question. Now, I had my quibbles about Wade’s book, but Reich tries to have it both ways, saying that Wade “combines compelling content with parts that are entirely speculative,” and “he does not identify any serious scholarship in genetics supporting his conclusions.” But Wade’s point is that, as Reich himself summarizes, “a politically correct alliance of anthropologists and geneticists has banded together to suppress the truth that there are significant differences among human populations.” Given that Reich says the same thing, though not quite so baldly, and that Reich is the type of person Wade thinks should be doing the “serious scholarship,” yet he makes very clear he has no intention of doing so, one can’t really complain that Wade doesn’t prove his points.

Wade relies heavily on Gregory Clark, whom Reich also tries to whack in passing. Clark suggests the possibility that the English developed genes for thrift, hard work, and patience, which helped them outrace the rest of the world and escape the Malthusian Trap in the Industrial Revolution. Reich points out that “transmission of culture” could explain the same thing. Which is entirely true—but it suggests some cultures are superior to others, something I am sure Reich knows he cannot openly maintain and keep his job. I can, though, and I suspect that culture is everything, and intelligence relatively little.

Reich, finally, tells some anecdotes that cast James Watson in a creepy light, but flunks his response to Watson’s claim that “African intelligence” (not a unitary thing by any means, as Reich proves) is lower than “ours” because that’s what “all the testing says.” This claim seems dubious to me, but Reich’s rebuttal is that “No genetic evidence for this claim exists.” Watson’s claim, though, is obviously not about genetic testing, which does not measure intelligence, but intelligence tests, which do, so this isn’t much of a rebuttal. Reich is on somewhat more compelling ground when he ascribes, at least as a possibility, the dominance of West Africans in sprinting competitions to a higher standard deviation, that is, higher genetic diversity, than among Europeans (though he does not relate this to average ability in sprinting, which perhaps can’t be reliably measured, but is critical to such an analysis, and in other places the center of Reich’s analysis). Such differences in standard deviation are known to explain why there are many more male geniuses (and imbeciles) than females (despite desperate attempts to pretend this is not true, yet another example of the corruption of science). Reich, at least, is very clear that truly enormous genetic differences separate men and women, although he doesn’t mention standard deviation, aware that this data is busy being suppressed because it explains why men have always made nearly all the spectacular intellectual accomplishments in human history, and always will, at least if “spectacular” is judged by reality, not by hope and dreams.

Reich is concerned that these political matters will hamper his scientific research, his “Manhattan Project.” He’s probably right to be concerned, but since this is a global effort (Reich gives full credit to his many collaborators), that’s unlikely to hold the science back—though it may hold Reich back. He’s also probably right to fear the resulting data will be mis-used in these conflict-ridden, atomized times, especially if those groups currently demonized by identity politics start organizing on the basis of identity, like others are encouraged to do, since no contradiction can exist indefinitely. He’s not responsible for that, though, and his book is an interesting read simply for the science.

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