Saturday, October 2, 2010

The evolution of Cavalli-Sforza. Part V

Inuit man making a soapstone carving.

The 1970s saw L.L. Cavalli-Sforza become a renowned human geneticist. His meteoric rise was made possible by two textbooks co-authored with Walter Bodmer: The Genetics of Human Populations (1971) and Genetics, Evolution, and Man (1976), as well as several joint articles in leading journals.

Nonetheless, his collaboration with Bodmer came to an end in the late 1970s (1). Why? No answer is given in his autobiography or in Stone and Lurquin’s biography. In fact, the autobiography has only three mentions of Bodmer. Two are single sentences. The one lengthy mention gives the impression of “damning with faint praise” (2).

To understand how this collaboration ended, one must understand how it began … in a triangular relationship that brought together not only Cavalli-Sforza and Walter Bodmer but also Joshua Lederberg, the leading geneticist at Stanford. It was the latter who helped him during the difficult postwar years, who invited him to Stanford in 1968, and who got him a permanent position there in 1972. It was also Lederberg and one of his protégés, Bodmer, who showed him the ins and outs of American academia, especially textbook publishing. Cavalli-Sforza naturally felt indebted to the two of them.

By the late 1970s, he had a long list of publications and felt reasonably secure. Perhaps he began to feel hindered by his collaboration with Bodmer. Or perhaps Bodmer seemed to be taking more out of it than he was putting in. Or perhaps …

One thing is clear. Cavalli-Sforza was planning to study how our species had evolved genetically under the influence of history and culture. Such plans could not include Bodmer, who knew little about human genetics and even less about the other two.

Cavalli-Sforza wanted to bring all three elements together to show that the natural environment has not been the main driving force of natural selection in our species. We have instead undergone selection by human culture—oral and written language, social organization, technology, means of subsistence, and so forth. In short, we have been created by our own creations.

This point was already being raised in the late 1970s as an argument against genetic determinism. Unlike other animals, we do not adapt to our environment through changes to our genes. We instead change our environment to make it better adapted to us. Therefore, it is our environment that does the changing, not our genes.

Cavalli-Sforza realized that this argument was overstated. Clearly, humans have changed genetically in order to inhabit a wide range of natural environments from the equator to the arctic. A Dinka and an Inuit differ anatomically and physiologically in many obvious ways.

But the critics of genetic determinism had missed another point. If our environment is now dominated by our cultural creations, it follows that these creations also dominate our adaptive landscape—we adapt primarily to our cultural environment and only secondarily to our natural environment. Thus, genetic change has come about primarily to make us better adapted to ourselves and our creations.

This in turn leads to two conclusions:

1. Human genetic evolution has accelerated in response to the quickening pace of human cultural evolution.

2. Each human culture has created its own adaptive landscape. Genetic differences between human populations have been primarily responses to cultural differences.

This line of reasoning has a name: gene-culture co-evolution. It can be traced back to Darwin, but there was a resurgence in the early 1980s with the writings of Robert Boyd and Peter Richerson, particularly Culture and the Evolutionary Process (1985). I had always assumed that it all began with that book, but the ground zero actually seems to have been a cultural evolution class that Cavalli-Sforza taught to Boyd and Richerson in 1978-79 (Stone & Lurquin 2005, p. 108).

Cavalli-Sforza wished to prove the existence of gene-culture co-evolution. In the mid-1980s, he organized a project with several professors from Queen’s University (Kingston, Ontario) and Université Laval (Quebec City) (3). The aim was to determine whether natural selection favors different mental toolkits in hunting and gathering societies versus agricultural societies. This rationale was later described by one of his project associates, John Berry, a psychologist at Queen’s University:

Hunters, by this way of thinking, require good visual acuity, keen disembedding skills and a well- developed sense of spatial orientation. To hunt successfully, the hunter must be able to discern the object of the quest (which is often embedded in a complex visual landscape), then disembed the object, and finally return to home base. In contrast, agriculturalists need not develop these particular skills, but rather they need to invest in other areas of development, such as conservation (in both the economic and the Piagetian senses) and close social interactions. (Berry 2008, p. 3)

In this joint project, Cavalli-Sforza wished to study Inuit artists to see whether their talent came from a genetic predisposition or from socio-cultural learning. This aim is spelled out in an unpublished report he wrote with Berry:

One of the most remarkable phenomena in the contemporary Canadian Arctic is the presence of highly-acclaimed art forms — carving in stone and ivory, and printing on paper. The question we ask is: how can we account for the wide-spread distribution of such talent in a small dispersed population?

[…] Is it possible that artistic talent is transmitted culturally (from parents to offspring, from others in society to the artist, and from peers to artist)? How can we assess these types of transmission?

Is it possible that artistic talent is transmitted genetically (from parents to offspring)? How can we assess such transmission?
(Berry & Cavalli-Sforza 1986, p. 2)

The Inuit population lends itself to such a study for several reasons:

With most individuals having had a reasonably fair chance and stimulation to become artists, one is in a better condition to study possible genetic factors contributing to artistic talent, if any. Another great advantage of carrying out this study among the Inuit is the frequency with which adoptions (also early ones, at birth) occur in this population. Frequencies of adoptions reported during the meeting varied from 15% to 30%. Adoptions allow one to distinguish cultural from biological inheritance by studying correlations of adopted children with foster relatives on one hand and biological relatives on the other.

The general strategy will be to select artists in specific communities (to be discussed later), and to study artistic talent in particular. Also to be studied are their biological and foster relatives (if any), including parents, brothers, sisters, children, and more remote relatives (when this is feasible and convenient). “Controls”, i.e. individuals who lay no claim to artistic talent, in spite of adequately trying, may also have to be selected and studied in a similar fashion.

[…] The study of traits other than artistic talent per se, that may be correlated with it (and indeed may be components of it) will also be of interest. Given enough information one can hope to separately estimate two quantities, called respectively cultural and genetic heritability (see examples in analysis of IQ).
(Berry & Cavalli-Sforza 1986, p. 5)

The project fell through. At Laval, we assumed there had been a problem with funding. At Queen’s, Cavalli-Sforza explained that he could no longer continue because of illness.

In their biography, Stone and Lurquin (2005) make no mention of illness during this period, the only bouts of ill health being an operation for bladder cancer in 1976 and a heart attack in 1991. In any case, ill health would have been a reason for postponing the project, not for canceling it.

Even more curious, this project is not mentioned in any of his publications, be they books, journal articles, conference proceedings, or poster sessions. The paper trail is limited to his one unpublished report (Berry & Cavalli-Sforza 1986). A similar blank appears in his writings on gene-culture co-evolution. Although he has written abundantly on this concept, there is surprisingly little on one key element: the impact of cultural evolution on genetic evolution. When he does give examples, he limits himself to the usual suspects: lactose tolerance in cattle-raising societies, and malaria resistance in tropical agriculturalists (Cavalli-Sforza & Cavalli-Sforza 2008, p. 264). There is no trace anywhere in his published writings of a belief that natural selection has favored different mental traits in different cultural environments (4).

And yet he held such a belief back in the mid-1980s—a time when he almost became his own man.


1. Google Scholar lists 26 joint publications by Cavalli-Sforza and Bodmer from 1970 to 1976. From 1977 to 2010, there are only 10 joint publications, 6 of which are re-editions or translations of textbooks from the 1970-1976 period. The remaining 4 are multiple-author articles where Cavalli-Sforza and Bodmer appear amid a long list of contributors.

2. Does Cavalli-Sforza make an oblique criticism of Bodmer in his autobiography?

“[…] unfortunately, [ambition] often makes you lose sight of the essential virtues, like honesty, moderation, and altruism. It can blind you. Some of my colleagues distinguish themselves more by their ambition than by their genius. I know others—these are the most dangerous or the most ridiculous—whose ambition is much greater than their intelligence.” (Cavalli-Sforza & Cavalli-Sforza 2008, p. 303)

3. This was the only time I met him. He sat in on my thesis committee meeting and looked on good-naturedly. Of the three other professors present, only one seemed to know just how important he was. Afterwards, that one professor was dumbfounded by our ignorance: “You think Claude Lévi-Strauss is important? This man is the Lévi-Strauss of human genetics!”

4. In fact, Cavalli-Sforza has denied having such a belief during the period in question. In his interviews with Stone and Lurquin, he stated that his interest in culture was motivated by the very opposite belief:

Yet another source of his interest in culture was the idea that the concept of human cultural learning was a valid weapon against racist arguments that differences between people (for example, different IQ scores among ethnic groups) were due to biologically determined “racial” differences." (Stone & Lurquin, 2005, p. 86)


Berry, J.W. (2008). Models of Ecocultural Adaptation and Cultural Transmission: The Example of Inuit Art, paper presented at the conference Adaptation et socialisation des minoritiés culturelles en région, June 3-4, Quebec City.

Berry, J.W., and L.L. Cavalli-Sforza. (1986). Cultural and genetic influences on Inuit art. Report to Social Sciences and Humanities Research Council of Canada, Ottawa.

Bodmer, W.R. and L.L. Cavalli-Sforza. (1976). Genetics, Evolution, and Man, San Francisco: W.H. Freeman.

Boyd, R. and P.J. Richerson. (1985). Culture and the Evolutionary Process, Chicago: Chicago University Press.

Cavalli-Sforza, L.L. and W.F. Bodmer. (1971). The Genetics of Human Populations, San Francisco: W.H. Freeman and Co.

Cavalli-Sforza, L.L. and F. Cavalli-Sforza (2008). La génétique des populations : histoire d'une découverte, Paris: Odile Jacob. (translation of Perché la scienza : L’aventura di un ricercatore).

Stone, L. and P.F. Lurquin. (2005). A Genetic and Cultural Odyssey. The Life and Work of L. Luca Cavalli-Sforza. New York: Columbia University Press.


Anonymous said...

Surprised you didn't mention Cavalli-Sfornza and Feldman "Cultural Transmission and Evolution" 1981.

Boyd and Richerson normally trace the beginnings of their field to the works of Donald T. Campbell. Though they did sit in on the course Cavalli-Sfornza and Feldman taught at Stanford.

Tod said...

I can't help thinking that one man is implicitly being held to a very high standard here. Cavalli-Sforza's reason for absenting himself from the debate might have been because he thought that - even though the dominant world view was wrong - going along with it fell into the category 'white lies' (such as we all tell to avoid hurting others feelings) rather than calculated careerism.

Maybe he thinks that the best way is to let reality slowly trickle into the zeitgeist. Cavalli-Sforza may believe that suddenly confronting a happily deluded world with the (brutal) truth would be the act of an ambitious man than a genius.

Tod said...

And maybe Cavalli-Sfornza was ahead of his time in being aware that these things are far less clear cut than the spin that ambitious researchers put on them.

ADHD's roots are complex

Anonymous said...

Peter, I admit that the evolution of Cavalli-Sforza and its relationship with political correctness is interesting but...FIVE POSTS AND COUNTING???

This blog was a delightful blog about the science of human evolution but, lately, it seems a blog about Cavalli-Sforza, who, despite his importance, it is only a scientist.

Peter Frost said...


I don't have a copy of "Cultural Transmission and Evolution" but I don't remember much in terms of gene-culture co-evolution. It was more about how cultural evolution displays both similarities and differences with biological evolution.


I can understand untenured scientists who engage in "passive collaboration", i.e., who say nothing because they fear for their careers.

This defense doesn't apply to Cavalli-Sforza. He is not exactly a junior scientist in an insecure position. He can and should speak out. Why do you think we give academics tenure? Indeed, because Cavalli-Sforza is tenured, people assume he says what he truly believes. Unfortunately, this is not the case.

He has also frequently crossed the line between passive collaboration and active collaboration, e.g., his 1970 article, which called for controls on research and thus legitimized the spread of "soft" academic censorship during the 1970s and 1980s.

I suspect that he thinks he's playing a "double jeu." In reality, he's ended up playing a "triple jeu."


It's important to understand how we have got to the position we are in now. Why has academic life become so monolithic? Why is there so little intellectual diversity? By understanding Cavalli-Sforza's academic trajectory, we can understand this process better.

This is not simply a story of bad people doing bad things. It's more a story of good people giving in to their own fears, and becoming their own worst enemies. Cavalli-Sforza has helped build his own cage, a cage that now seriously constricts academic debate and research.

Tod said...

Cavalli-Sfornza's wartime activites would be irrelevant to any scientific debate and the man is beyond career considerations, does that not suggest that it's the wider reaction he is worried about ?

While no one gets diagnosed with 'creeping schizophrenia' (Soviet - style) for openly dissenting from the dominant worldview in the West what does happen is their personalties become the issue.

I think scientists know they can never really win against that kind of thing. Scientific iconoclasm of the type you are calling for has profound ideological implications, it could only have come as part of a wider culture movement.

Peter Frost said...


I don't expect academics to be martyrs. But I do expect the following:

1. Say only what you truly believe.

2. If, for career reasons (i.e., lack of tenure), you cannot say what you believe, say nothing.

3. Never be an accomplice to a lie. At the very least, simply say: "I cannot make up my mind until I can hear both sides of the question. Please let me hear both sides."

I agree that Cavalli-Sforza has nothing to lose at his age. He could and should speak up. As for why he doesn't, I suspect a big reason is still his fear of being blackmailed over his wartime activities.

Frankly, this is not a reasonable fear. Mitterand confronted his fascist past near the end of his life, and was not condemned by the court of public opinion. The same was true for Pierre Elliot Trudeau. He could have destroyed the incriminating evidence from his past. Instead, he chose to offer himself up to the judgment of history.