I am not persuaded by his argument, which he derives from Pierre van den Berghe and Frank Salter, that ethnic affiliation is an evolutionary adaptation, in that those who favor their ethnic community over others are practicing an extended form of kin selection that advances their ethnic genetic interests.
I am persuaded that evolved human nature is inclined to tribal thinking, so that we naturally categorize people as us and them, and we naturally favor our group over others. And while the social conditions of life have often predisposed people to make this in-group/out-group division along racial and ethnic lines, there is no evidence that this predisposition is an innate adaptation of the human mind.
On the contrary, there is lots of evidence that while we are innately inclined to look for cues of coalitional affiliation, the content of those cues depends on social learning; and people in multi-racial and multi-ethnic societies can be taught to be cooperative without regard for racial or ethnic boundaries. In fact, Frank Salter implicitly concedes the truth of this point when he laments that ethnic nepotism is not instinctive, and therefore serving ethnic genetic interests requires artificial cultural strategies devised by modern scientific reasoning, and that no ethnic state has ever succeeded in securing an adaptive ethnic group strategy.
This debate over whether racial and ethnic identity is an evolutionary adaptation has implications for the current debate in North America and Europe over immigration policies. In On Genetic Interests, Salter argues that opening a nation's borders to immigrants is contrary to the genetic interests of the native population. People of European descent have been the majority of the population in the United States and Europe. But with increasing non-European immigration, those of European descent will eventually become the minority, and at some point the European ethnies will be completely replaced by non-European ethnies. (Salter has followed van den Berghe in coining the word "ethny" as a substitute for "ethnic group" as the term for a population sharing common descent, but whose members are so numerous that they cannot form a group.)
To protect the genetic interests of these ethnies--to prevent their extinction in the genetic competition with other ethnies--Salter argues for "universal nationalism": each nation should have a right to protect its distinctive ethnic identity by restricting or prohibiting the flow of immigrants who do not share its ethnic identity. There would be ethnic equality in that every ethny would have a right to its own ethnic homeland. But there would also be ethnic inequality in that every ethnic homeland would discriminate against foreigners with different ethnic identities. Every nation would have the right to practice ethnic nepotism.
Sanderson does not recognize the two major problems with Salter's argument. The first problem is that what Salter identifies as "ethnic genetic interests" have no roots in the evolved instincts of human nature, and thus Salter's strategies for protecting those interests must be artificial contrivances of reason. Salter admits that in protecting their genetic interests in modern states, "humans can no longer rely on their instincts" (28). Human beings have evolved instincts for individual survival and for the reproductive interests of their families and their extended tribal groups. But in the environments of evolutionary adaptation, our foraging ancestors had no experience with ethnic identities that might embrace millions of anonymous individuals scattered around the world.
The very idea of "ethnic genetic interests" depends on a scientific knowledge of genetics that has not been available to human beings until recent decades. Even most evolutionary psychologists and sociobiologists don't recognize ethnies as extended kin groups.
There is evidence for evolved instinctive tribalism by which we distinguish between in-group and out-group. But the cues for identifying who belongs to which group are set by social experience that is not instinctive but learned. As Salter admits, the famous social psychological experiments of Muzafer Sherif, Henri Tajfel, and others have shown that people identify with groups of all kinds and develop ethnocentric attitudes towards out-groups based on arbitrary cues. In laboratory experiments, people can be randomly assigned to different groups based on arbitrary factors--such as flipping a coin to identify some people as "heads" and others as "tails"--and then those groups will try to outcompete one another.
One of the most revealing experiments is not cited by Salter. Robert Kurzban, John Tooby, and Leda Cosmides have shown that racial categorization in identifying coalitional alliances can be eliminated when the cues for coalitional affiliation do not track race ("Can Race Be Erased? Coalitional Computation and Social Categorization," Proceedings of the National Academy of Sciences 98 : 15387-15892). Their experiment was designed to test their hypothesis that the human mind evolved to track coalitions--to decide who is allied with whom--but that the coalitional code is learned by experience and that there is no evolved instinct for seeing race and ethnicity as the cues for coalitional assignment. Their hypothesis arises from the thought that in the environments of evolutionary adaptation, foragers would have experienced group competition, but they would not have generally encountered members of different races.
Kurzban, Tooby, and Cosmides asked volunteers to look at eight photographs of young black and white men and women wearing the same gray jersey. Associated with each photograph was a sentence suggesting group conflict--such as "They were the ones who started the fight"--and it was arranged so that it was clear that these eight people were split into conflicting pairs.
The volunteers were given a "distractor task" to get their minds off the subject. They were then asked to recall which sentences went with which photographs. The distraction was designed to force them to rely on their unconscious feelings rather than their conscious memories.
Even though the two sides in the fictional fight were racially mixed, the volunteers tended to pair blacks with blacks and whites with whites, as though they assumed that conflict would be based on racial differences.
But then, in the next experiment, everything was the same, except that some of the jerseys were yellow instead of gray, and the sentences implied that the conflict was between the yellows and the grays and not the blacks and the whites. Most of the volunteers easily picked up the hint that the conflict was based on the color of the jerseys rather than the color of the skins. Kurzban, Tooby, and Cosmides concluded: "Despite a lifetime's experience of race as a predictor of social alliances, less than four minutes of exposure to the alternate social world was enough to deflate the tendency to categorize by race."
So it seems that the evolved human mind has an instinctive coalitional codemaker, but the codebook is not naturally instinctive but socially learned. That explains why in appealing to "genetic interests," Salter cannot rely on human instincts to tie those interests to racial and ethnic identities, and why he complains that modern multiethnic societies have gone a long way towards teaching people to feel social solidarity that transcends the boundaries of racial and ethnic identity.
This also explains Salter's second big problem. He tries to formulate various strategies for defending ethnic genetic interests in modern states. But he admits that probably none of them will work very well. He identifies various "ethnic states" in the modern world, but he admits that "no state yet developed has reliably kept its promise as an adaptive ethnic group strategy" (221), which includes "the best known modern ethnic state"--Nazi Germany (231). For example, none of the ethnic states he mentions have succeeded in raising the total fertility rate of its ethny. The drop in the total fertility rate for native Germans continued under the Nazis, and the Germans have one of the lowest fertility rates for any population in the world. Other modern ethnic states that Salter mentions--such as Malaysia--show the same failure to raise fertility rates. Malaysia provides special protection for the Malay majority at the expense of the Chinese and Indian minorities, and yet the total fertility rate for Malays have fallen below replacement levels. (I have written about low fertility in the demographic transition.)
All of this leads me to conclude that while there might be a natural desire for tribalism, the expression of that tribalism as racial or ethnic identity is not natural but cultural.
Some of my posts on the biological reality of race can be found here, here, here, and here.