Ashley Montagu on recent evolution

Ashley Montagu was a British anthropologist, born under the name Israel Ehrenberg. He moved to the United States for work at Columbia for his Ph.D work, after he finished a degree in psychology from University College London. He therefore wrote on biological aspects of anthropology from outside the training perspective of the Harvard school, founded by Earnest Hooton and including other prominent 20th century anthropologists such as Sherwood Washburn and William W. Howells. Montagu became a central figure in the drafting and passage of the UNESCO Statement on Race, first drafted in 1951. Montagu died in 1999.

Like Hooton before him, Montagu became an important public face of anthropology. He wrote many popular books, related not only to race but also the psychology of the mother-infant relationship, aggression, and human evolution. He made frequent television appearances. Later in life, he advocated the global abolition of genital mutilation.

By 1951, Montagu was widely known as a critic of the biological race concept, in large part because of his 1942 book, Man’s Most Dangerous Myth: The Fallacy of Race. In the preface of that book, Montagu described how he recoiled against the race concept as applied by his instructors in England, singling out Karl Pearson for particular criticism. Many of his scientific arguments against race may be traced directly to Frans Boas, although Montagu was more strident.

A full accounting of Montagu’s writings on the race concept is more than I can undertake here. But I want to draw attention to one of Montagu’s arguments. Along with the UNESCO Statement on Race was published an annotated version, including comments by Ashley Montagu on each of the Statement’s sections. The short book provided an interesting opportunity to expound with short essays on several points of relevance to the scientific concept of race.

In one section, Montagu directly addresses the possibility that recent human evolution has had important effects on present-day variation:

While it is not possible to say with certainty that significnat genetic factors do not enter into the differences in cultural achievements of different peoples, the probabilities appear to be very much against such a contingency. What is most probable is that the genes that render cultural achievement possible are fundamentally similar in all the populations of humanity. The reason why it is possible to say this with a high degree of probability is that during the several million years or so of man's evolution the selective processes which have been at work on him must have been much the same in all populations.
Throughout the evolutionary history of man he has been a food-gatherer and hunter. It is only during the last 15,000 years of his history that some populations developed agriculture and some went on to develop an urban way of life. All of man's basic potentialities and traits were developed long before that time. Under food-gathering and hunting conditions of life, populations are small and the challenges of the environment, differing as they may from the jungles of central Africa and South America to the icy wastes of the Arctic, remain fundamentally similar. What is required under such conditions of life is the ability to meet the daily demands of life with the necessary adaptive responses. The traits having the highest adaptive value under such conditions are plasticity, malleability, cooperativeness, and the general intelligence which enables the individual to make the most appropriately successful responses to the challenges of the environment. In the course of man's evolution the selective pressures acted not toward the development of any particular ability, but toward the generalized ability of adaptability. Hence, there would have been no development of genetically based special abilities in one population differing from those developed in other groups. Since there was no particular premium placed upon the development of such abilities, there would have been no selection for them in any group.
It is man's generalized ability to adapt himself to all environmental conditions and challenges, not a fitness in one spcial ability or another, which has been at the highest premium in the course of his evolution (Montagu 1972: 174-175).

This passage is part of a longer section, making the argument that natural selection on cognitive or social characteristics should have been constant across different human groups, because the social environment was constant, even if the physical environment may have varied. This is also the same kind of argument made by those who think that human evolution is not presently occurring, because they claim that culture has replaced natural selection.

Montagu makes many arguments concerning race that I agree with. However, it is obvious that I disagree with this one. Montagu’s argument here is not a fact, but a hypothesis about the form of past selection. It entails several assumptions, including:

  1. That none of the genes that affect cognitive traits have been correlated by pleiotropy or epistasis with other traits.

  2. That “generalized ability” is a unitary trait that does not have parts that might be separately correlated with survival.

  3. That natural selection is a slow process that takes “millions of years”.

  4. That prehistoric humans did in fact effectively eliminate all covariance between “cognitive or social characteristics” and survival and reproduction.

These assumptions are either known to be false or are likely to be false.

The last introduces circular logic. It amounts to this: “Modern people cannot vary in social or cognitive characteristics because ancient people did not vary in those characteristics.” But surely, if ancient people had invented a social system that selected so strongly on social and cognitive characteristics as to eliminate any standing variation (making populations uniform), then any new mutation that affected the social and cognitive characteristics would immediately be strongly selected. Unless we further assume that humans are perfectly optimized and further fitness increases by new mutations are impossible in principle.

Plenty of evidence rejects the assumption that there is only one dimension of social and cognitive abilities in living people. The human adaptation to culture involves many partially independent dimensions of ability, each varying within populations of living people. Our own work on recent selection shows why the third assumption is false – empirically, selection has been rapid for many characteristics in the human populations of the last 10,000 years. There is no reason to assume that changes cannot occur given hundreds of generations, or that changes need be in the same direction as in Pleistocene humans.

Since publishing our work on recent natural selection in humans, I have often been asked by journalists what I think the findings mean for the concept of race in humans. If humans have been rapidly changing, doesn’t that mean that there ought to be lots of genetic differences between different populations? If humans are different, won’t that give aid and comfort to racism? Isn’t there a danger that genes will prove that one group is better than the others?

I have a pair of identical twins. I also have two other kids. My twins are genetically the same. My other kids are not. How should I treat them?

I hope it doesn’t take much reflection to realize that their genetic identity should not determine their equality. Now, they may have different talents and abilities. There are things I expect of one kid that it would be unreasonable for me to expect of her sisters. But that’s also true of my identical twins, who each have different talents and abilities. Environment plays a role, as well as genes. When we think of human groups, we also must remember that individuals vary more than populations do.

There are already, today, genetic tests that promise to inform us about cognitive phenotypes. One gene in his entire genome, James Watson did not want to discover or make public: APOE. The reason was its link in European populations to Alzheimer’s disease – in other words, a cognitive phenotype. The effect of this gene varies by ancestry – it does not have a strong link to Alzheimer’s in African populations, for example. And the connection of this particular gene to cognitive ability might best be described as epistasis. It may have nothing to do with selection on cognition or social characteristics.

When we consider the form of such genetic relationships, we can see a deeper error in Montagu’s argument. He thought in terms of genes that had singular effects on cognition, that were selected in the past on that singular basis.

Probably there were some such genes, for which the most significant correlation with fitness was their effect on cognition. Some human populations have inhabited such distinctive social environments in the past 10,000 years – abandoning small hunting and gathering groups and settling in villages and cities, that there may well have been selection on personality or other traits that influence group life.

But so many genes are involved in the brain. Many, probably most, of the genetic effects on cognition may have been side-effects of selection on other traits. Others were doubtless subject to advantages in some circumstances and drawbacks in others. As Gary Marcus put it in a book last year, the human brain is a “kluge” – an imperfect solution built by jerry-rigging.

It is silly to suggest that one population will be found to have a perfect brain and the others will be found wanting. Our brains are all flawed in gloriously variable ways. It is equally silly for us to use these flaws as justifications for moral inequality.

References:

Montagu A. 1972. Statement on Race. 3 ed. Oxford University Press, New York.