A Troubling Distortion of Science – A Review of A Troublesome Inheritance: Genes, Race and Human History by Nicholas Wade.

Sy Garte and Aniko Albert

The use of pseudo-scientific arguments to advance philosophical and political agendas is quite familiar to most readers. From eugenics to Lysenkoism to some of the anti-theistic arguments of the new atheists, the name of science has been misused to cloak questionable ideas in a mantle of unassailable truth. This is a dangerous game, since the public is generally ill-equipped to distinguish real scientific arguments from those that sound scientific but are in fact specious.

The new book by Nicholas Wade, “A Troublesome Inheritance” (1), is indeed a troubling example of non-science being used to bolster a bad idea. In particular, the book is a good illustration of the dangers of certain widespread misunderstandings about the science of evolution and genetics. Wade claims that “researchers at present routinely ignore the biology of race…”, by which he means the genetics of race. He concludes that human evolution proceeded recently and divergently among “the three major races” and that such “genetic evolution” explains many behavioral differences, including, among other things, why Jews are smart, and why western cultures are more technologically advanced than others.

In fact, Wade’s book is an attempt to explain why “the West” rose to economic and political prominence in the past five hundred years (and why, he seems to fervently hope, it is not about to lose its leading position to Asia, as some predict). His answer is that the West owes its success to genetically evolved social behaviors. Wade claims that human genetic evolution has continued in historical times along “racial” lines – that it has been “recent, copious and regional”.

In his review of human history over the past ten thousand or so years, Wade makes frequent references to the idea that genetic changes were involved in each major transition. We are told, for example, that within the few centuries just prior to the Industrial Revolution, people in England genetically evolved to be less violent, more hardworking, and more trusting of government and strangers in general, while people in the Middle East remained largely tribal in their behaviors and Islamic civilization declined as a consequence. The proposed reason for this difference is that in the Middle East the more trusting, modern-state-compatible behaviors were not selected for, because people lived under “largely predatory” regimes that “extract[ed] taxes from their citizens but provide[d] few services.” How this circumstance was not true for medieval England is not clear, and of course the actual genes supposedly responsible for these changes are not identified.

In many parts of the book, what Wade claims to be a central concept is nicely refuted by his own writing. When it comes to the question of how many races there are, Wade usually refers to three or five “major races”, and admits that it is possible to think of seven races. He even says “the more DNA markers that are used… the more subdivisions can be established in the human population”. It isn’t clear why Wade doesn’t see this as a fatal error in his overall thesis. He is absolutely correct that the number of races defined by genetics is indeterminate, and that fact renders the concept of racial biology meaningless. Furthermore, if one were inclined to divide the human population into three groupings according to genetic distances (F_st), they would not be Africans, Asians and Europeans (as Wade says), but Africans, Australians and everyone else, including everyone from Asia, the Americas and Europe.

In his discussion of the genetics of populations, Wade follows a minimalist definition of evolution as an inherited change in the allele frequencies in populations. Allele frequencies differ to various degrees among all populations, defined in any way one likes. Most people think of evolution as the mechanism by which new species arise from common ancestors (descent with modification), but this is emphatically not what Wade is talking about.

The fact that there is some extent of allelic frequency variation in the human population (but actually very little compared to other primates) does not in any way imply evolutionary changes leading to permanent divergence, which requires fixation of alleles in defined, and usually isolated populations. For example, we know that chimpanzees and humans evolved from a common ancestor, and the differences between chimp and human behavior are understood to be genetically fixed and a result of evolution. From this, it follows – Wade tells us – that the differences in social behaviors between different human cultures are the result of genetic evolution, too.  But even Wade admits that none of the human allelic changes found between populations have become fixed, all of them are reversible, and they do not lead to permanent or significant alterations in the critical phenotype of any human population. The analogy to human/chimp evolution is scientifically absurd.

While it is true that Africans have some unique genetic polymorphisms (one of which was discovered by one of us (2)) and that the mutations allowing for malaria resistance and lactose tolerance in adults began as regional changes under strong selection, these examples of population-specific genetic alterations actually refute rather than support Wade’s racially based evolutionary claims. Lactose tolerance began as local variants, but has spread over the globe, and is still spreading.

Among the most telling cases of self-refutation of Wade’s hypothesis is the example he gives of African Americans losing the sickle cell trait SNP because malaria is no longer providing a strong selection pressure on this population.  His example refutes the idea that Africans have undergone any sort of actual evolution, since within a very brief time span, the proposed phenotypic segregation of Africans due to selection for the S allele in hemoglobin is being reversed. The same kind of malleability is true of many so-called racial features such as skin color and body shape.

Human populations have been on the move and intermixing for the past 50,000 years. While some human genetic isolates exist, they are rare and represent a tiny fraction of the total human population. Wade does admit that there exist some populations that he calls “admixed”, such as the modern residents of Ethiopia, who are genetically more European than African. But what he doesn’t seem to understand is that all human populations are mixed – there are no genetically “pure” populations. Even the Icelanders, who many scientists thought would be homogeneous enough to allow for studies of Mendelian inheritance of disease traits, turn out to be just as mixed as the Germans, the Japanese, and so on. The idea of a pure race is pure myth.

Wade speculates that Jews have undergone some kind of selection for genes conferring higher intelligence because some of them (actually the wrong ones, but we don’t have the space to discuss Wade’s numerous historical errors) were bankers during the middle ages. Wade bases this absurd idea on a misunderstanding of the scientific literature. He cites papers from the Goldstein group to claim that Ashkenazi Jews are a distinct genetic grouping. What the key paper (3) actually showed was that by principal component analysis of 550,000 genetic markers, Americans who claimed to have four Jewish grandparents can be genetically identified and differentiated from non-Jewish Europeans. This does not mean that Jews differ in any allelic or gene frequencies (soft sweeps) from Europeans, but only that principal component analysis of half a million markers can detect familial relationships. The same result would be obtained comparing Welsh and English people, or two neighboring towns in Germany. In fact, the data used for the paper includes Jews from Russia, Poland and Lithuania, whereas the non-Jews are from Italy, UK and Germany. It would be quite surprising if the results presented in the paper were not obtained.

Despite being a respected science journalist, the author frequently fails to distinguish between scientific arguments based on data, and conjectures that aren’t. Two examples illustrate this serious deficiency. Wade mentions the work of Richard Lewontin on human genetic diversity within and between populations. Wade does not dispute Lewontin’s findings that there is less genetic variation between populations than between individuals regardless of what population they belong to (15% vs. 85%). To counter this, Wade invokes Sewall Wright, one of the pioneers of population genetics, as quoted in the textbook Principles of Population Genetics by Hartl and Clark (4). Wright is quoted as saying that an F_st of 15% between populations indicates a major difference between potential subspecies. What Wade leaves out is that this is only true if the within-population F_st is much lower. The very same textbook clearly indicates that the total average human F_st (given as 0.069) is less than that of different villages within the Amazon tribe of the Yanomamö (0.077), confirming Lewontin’s point.  Neither Hartl and Clark nor Wright disagreed with Lewontin’s conclusions on the relative importance of genetic diversity within compared to between populations.

Even more troubling is Wade’s reasoning as to why “Wright’s judgment” should be preferred over Lewontin’s (as if the two were in disagreement). Wade says “Wright was one of the three founders of population genetics… Wright invented the fixation index… Wright, unlike Lewontin, had no political stake in the issue.” Even if there had been any controversy, these are not scientific reasons to choose one side over another. Notice that evidence is not even mentioned. Wade seems to have forgotten that one of pillars of the scientific revolution was the fall of the argument from authority as trumping actual evidence.

The second example relates to Wade’s discussion of Jared Diamond’s ideas concerning the reasons behind differences in technological and cultural achievements between populations, which Diamond asserts have nothing to do with genetics.  To set the tone, Wade consistently identifies Diamond (who, unlike Wade, has a PhD in physiology and biophysics), as a “geographer”. Diamond’s theory, Wade declares, is driven by ideology – the desire to deny the importance of race – not science. This is a moment of high irony, given the thoroughness of Diamond’s data and the admitted lack of actual genetic evidence for Wade’s own conjectures about racial differences in social behavior.

Wade’s misunderstanding – or misrepresentation – of Diamond’s argument goes as far as declaring that the case of Australia disproves Diamond’s theory, since as soon as the Europeans appeared, they started a thriving modern “European economy” on a continent where native societies had been stuck in the Paleolithic Age. Any cursory reader of Diamond (5) could point out the obvious omission: at the root of the Europeans’ “economic method” was the agricultural package (wheat, barley, sheep, and cattle) domesticated in the Fertile Crescent about 10,000 years ago. In other words, the Europeans did not work with what was available on the Australian continent, which is what the Aborigines would have had to do, but with the very “founder package” that in Diamond’s theory gave Eurasia its advantage. There were in fact no domesticable species on the Australian continent that could have provided the Aborigines with a viable agriculture, and this is, of course, Diamond’s point. Nowhere is the disconnect between facts and Wade’s presentation as acute and his substitution of rhetorical flourish for evidentiary argument as obvious as in his discussion of Jared Diamond´s ideas.

Regarding his own theory, Wade states that even though social behavior is difficult to attribute to specific genes, “nonetheless, it is reasonable to assume that if traits like skin color have evolved in a population, the same may be true of its social behavior”.  This is a staggeringly unscientific statement in a book supposedly devoted to science. Wade gives no examples of specific alleles that might account for such differences, since of course none are known. He also admits that such traits are likely to be multigenic, and almost impossible to detect, in addition to the fact that what constitutes differences in social behavior is not easily measurable.

Therefore we don’t find his proposition reasonable at all. Social behavior is known to be highly variable both between and within populations as a function of environmental and social change, which occur very rapidly. While skin color is under enormous and constant selection pressure, even that phenotype requires thousands of years to manifest. The parallel between skin color and social behavior fails on temporal, genetic (the genes of skin color are complex, but probably much less so than those related to “social behavior”) and selection criteria grounds.

One of the more obnoxious themes of the book is the claim that “social scientists” who deny the biological reality of racial genetic differences are motivated by a desire to be politically correct. Wade quotes extensively from statements by anthropologists typical of this view. It is both insulting and demeaning to characterize the scientific positions of the majority of anthropologists, population geneticists and evolutionary biologists as deriving from political motivations. This charge reminds me of similar claims made by some climate change denialists about the scientific consensus of climatologists.

There is a great deal of correct information about genetics in this book, and a few useful explanations of some basic aspects of evolution. But none of the correct information is new or controversial. On the other hand, many of Wade’s key ideas regarding human racial differences (which are also not new) are deeply flawed scientifically, and most of them are refuted within the book. Wade’s central thesis of recent, rapid and regional human evolution is based on misinterpretations of the literature of human population genetic variation, and a misleading interpretation of biological evolution in human beings.

While science remains the most powerful tool for understanding the world, and Darwinian evolution is the best explanation for how biological change happens, the misuse and misinterpretation of science clearly remain an obstacle to all who seek truth. The Christian belief that all human beings are made equally in the image of God is a matter of faith and not a scientific statement, but there is still no scientific evidence to refute it.

References

1. Nicholas WadeA Troublesome Inheritance: Genes, Race and Human History. Penguin Press New York 2014

2. Crofts F, Cosma GN, Currie D, Taioli E, Toniolo P, Garte SJ. A novel CYP1A1 gene polymorphism in African-Americans. Carcinogenesis.1993 Sep;14(9):1729-31

3. Need AC, Kasperaviciute D, Cirulli ET, Goldstein DB A genome-wide genetic signature of Jewish ancestry perfectly separates individuals with and without full Jewish ancestry in a large random sample of European Americans. Genome Biol. 2009;10(1):. Epub Jan 22

4. Daniel L. Hartl and Andrew G. Clark Principles of Population Genetics 3^rd Ed. Sinauer Assoc. Sunderland MA 1997

5. Jared Diamond Guns, Germs, and Steel: The Fates of Human Societies W. Norton New York, 1997.