In an eSkeptic last month, we ran dual reviews – one positive and one critical – of the Vince Sarich’s and Frank Miele’s book, Race: The Reality of Human Differences. In response to that eSkeptic we received a thoughtful letter from long-time Skeptic subscriber Chuck Lemme, an engineer from Tucson, Arizona with a deep interest in and knowledge of evolutionary theory. Lemme suggests that Sarich and Miele neglected to consider sexual selection in their analysis of the origins of human racial diversity, and instead focused too exclusively on natural selection. For this week’s eSkeptic, we present Lemme’s interesting letter and a thoughtful response from Sarich and Miele.
Race & Sexual Selection
a letter from Chuck Lemme, Tucson, Arizona
I thoroughly enjoyed the recent eSkeptic reviews of Vince Sarich’s and Frank Miele’s book Race, but I was somewhat surprised that none of the writers, neither of the book nor the reviews, mentioned Darwin’s convincing argument as to the “main agent in forming the races of man” (letter to Wallace, 1867). This main agent was the subtitle to his book Decent of Man, Selection in Relation to Sex. I don’t think that sexual selection has fallen from favor as a potent force in directing evolution; in fact, Amotz Zahavi has given it new credibility in the last couple of decades with his concept of honest fitness signals for intra- and inter-sexual communication. Fisher put sexual selection on a firm mathematical footing in the 1930s, showing that female whims in future generations match those inherited from the past because the genes are passed to both sexes. That is, males inherit the genes to produce the trait and females inherit the genes to prefer the trait (or one can reverse the sex roles and get the same result).
Jared Diamond, in The Third Chimpanzee, states that because mate selection is so important among humans, sexual selection is enhanced (p.64). He further states (pp.112–121) why he believes “visible human racial variation to be largely a by-product of the remodeled human life cycle.” He wrote, “sexual selection had a big effect on molding the external traits by which we pick our mates” (p.120). Richard Dawkins agrees with Diamond’s assessment of Darwin’s idea (A Devil’s Chaplain, p.76) and wrote a whole chapter on sexual selection and its relevance to human races (“Light Will Be Thrown”).
The differing, superficial racial characteristics are only visual and run the gamut from skin color, hirsuteness, steatopygia (large fat deposits on the buttocks), exaggerated labia minora, conical versus hemispherical breasts, and eyes with and without epicanthic fold, to name a few. None involve liver function, developmental rates or composition of the proteins that make up kidney tissue. Our insides do not vary like our outsides. The racial characteristics are all truly superficial, involving what the opposite sex can see. Although skin color might have some adaptive advantage as a function of latitude, there are so many counter examples as to make even this to be under only slight adaptive pressure. All the other racial characteristics that we use to classify humans into races have no adaptive use at all but are all very visual and obvious to others. So, how did they diverge to such a large degree in the 100,000 years or so that we have been human? Darwin’s answer of sexual selection still is the most persuasive to me.
Anytime a characteristic changes rapidly it is likely that neither genetic drift nor adaptation is at work because they work too slowly. Only sexual selection can direct rapid movement in genetic makeup. This is the main thrust of Geoffrey Miller’s book, The Mating Mind. Miller contends that the mental traits that make humans unique – language, art, morality, and others – are similar to a peacock’s feathers; that is, they are honest fitness indicators. He states that the mind’s most impressive abilities are “courtship tools, evolved to attract and entertain sexual partners” (p.4). It makes much more sense to me that sexual selection was the mid-wife for the rapid evolution of our large brains and the minds that inhabit them.
I agree that it is ridiculous to dismiss race as something that does not exist at all, as anyone can make reasonable classifications for groups living far apart; yet I also think that the evidence shows that the differences that produce the races are superficial and not driven by adaptation. I think that Sarich’s and Miele’s search for adaptive reasons for race are ill considered, especially in light of the arguments for the power of sexual selection. There are no borders that separate the races. There are no clear lines of demarcation, as the superficial characteristics that determine race are not discrete, but rather blend as one traverses geography. One can tell a Swede from a Nigerian, but has difficulty discriminating between a Pakistani and a Hindu or an Afghan. But, I think, the strongest argument against their conclusions is the uniformity of humanity. We have one of the smallest genetic variations of all the mammals, with only cheetahs, inbred lab rats, and some threatened species with very small populations having less variability. There is more genetic variation in any one “race” than there is between the means of all the races. That is, if you take any large sample of humans and measure their genetic variation, there will be more variation among the individuals of the group than the variation of that group’s mean compared to the mean of any other group. We are a very uniform species with some quite recent, sexually stimulated, superficial variations.
Race & Race Differences are Real
a response to Lemme’s letter
by Vincent M. Sarich and Frank Miele
Chuck Lemme criticizes our book, Race: The Reality of Human Differences, on two grounds: first that “racial characteristics are all truly superficial,” and that “none involve liver function, developmental rates or composition of the proteins that make up kidney disease. Our insides do not vary like our outsides.” Second, since racial characteristics are allegedly solely in “what the opposite sex can see,” he cites Darwin, Jared Diamond, and Richard Dawkins that human racial differences are almost entirely the result of sexual, not natural selection.
We did not say more about the matter of sexual selection because we do not regard it as a coherent explanation of human racial variation. In reading Richard Dawkins’ The Ancestor’s Tale, where he puts forward the idea that bipedalism was the result of sexual selection (pp.267–270), we recognize a need to expand on our reasoning in this regard. Bipedalism constitutes a speciation event involving a degree of morphological change enormously beyond the racial level. Then why dismiss sexual selection operating at the lower taxonomic level? Probability. Which is more likely: that sexual selection took place in each racial lineage more or less synchronously, early on in its history, or that the same process of adaptation to the environment took place in our species as has been well documented in others?
For example, Bergmann’s Rule and Allen’s Rule state that those in cold regions are heavier than those in the tropics, with a higher ratio of extremity length to trunk length, and greater weight per unit of stature. Why? Maintenance of body temperature. The sphere has the least surface area of any shape of equal volume. Are the body builds of the Inuit and the Tutsis more likely the result of natural selection or sexual selection? Not only body build, but head shape is correlated with latitude.
Lemme asserts that “natural selection could not have produced the pronounced observable racial differences in 100,000 years.” The Inuit/Tutsi example provides one clear refutation. No one believes that the separation between those two groups is anywhere near that ancient, and yet there can be little doubt that natural selection has been very hard at work.
Lemme buttresses his assertion with the statement that we “have one of the smallest genetic variations of all the mammals.” In fact, the amount of human genetic variation is commensurate with the times of separation for the lineages. Natural selection could have turned Tutsis into Inuit in, at most, a few tens of thousands of years.
The incongruity in distance between neutral genetic markers and morphological features also applies to interspecific comparisons. The differences between pygmy and common chimpanzees on the one hand, and humans on the other, are only about 1.5% in neutral DNA markers; between the two chimpanzees less than half that. Yet the physical and behavioral differences between apes and humans are immense; even between different species of apes they are substantial.
On page 212 of Race we note the seminal insight of anthropologist Glynn Isaac that “the shorter the period of time required to produce a given amount of morphological difference, the more selectively/adaptive/functionally important these differences become. Race and race differences are real, and we document that fact in a number of converging lines of evidence: everyday observation (even by naïve three-year olds), the art and language of ancient and non-Western civilizations and cultures, measurement of skulls and of blood group frequencies, analysis of mitochondrial DNA (which traces the female ancestral line), Y-chromosome DNA (the male line), autosomal (i.e., non-sex chromosome) DNA, and Short Tandem Repeats (STRs). This would be just as true even if they were the result of sexual selection.
In our book, Chapter 7 (“Race and Physical Differences”) and Chapter 8 (“Race and Behavior”) use the example of wolves and dog breeds to demonstrate that an exceedingly small difference in neutral genetic markers (the use of which in “clocking” evolution one of us [VS] pioneered) produces immense differences in morphology and behavior. (The artificial selection exercised by breeders is nothing but “evolution run in fast forward.”) As noted, the race and skin color of a serial killer were determined from analysis of his DNA (p.22). Interestingly, about the same number of gene loci are needed to distinguish among dog breeds as among human races.
Our Chapter 7 clearly documents that human racial differences are definitely more than “skin deep.” Racial differences in cranial morphology are greater than those between species of chimpanzees or gorillas! Forensic anthropologists routinely identify the race of human skulls, as is regularly depicted in “Crime Scene Investigation” TV shows.
Much more important are racial differences in physiology (body chemistry). When you go in for a medical exam, one of the first things they do is get your family history. Races are simply super-extended families. One life and death example: Individuals of African origin suffering from hypertension do not benefit as much (on average) from ACE (angiotensin converting enzyme) inhibitor as do individuals of European origin. Nitric oxide, a gas that is normally produced by the cells that line the blood vessels, dampens the contraction of muscle cells, relaxes and thereby lowers blood pressure. Blacks, however, are more likely to have a nitric-oxide insufficiency. A new hypertension medication, BiDil, which replenishes nitric oxide, has been approved by the FDA with support from the Association of Black Cardiologists and the Congressional Black Caucus.
The example of BiDil shows why a society that truly values diversity should recognize the reality of race. The reason for studying race is not to put anybody back to the back of the bus, but to put everyone on the path to leading a better, more successful life.