Was evolutionary psychology inevitable?

Cover of Time, August 28, 1995. Evolutionary psychology beat out its rivals in the race to win public acceptance.

During the 1990s, evolutionary psychology overtook and replaced sociobiology. Its success was total, much like that of many paradigms we now accept as normal science. Did it succeed for the same reason? Did it better fit the data?

In some ways evolutionary psychology was better than its rivals and in other ways worse. Its superiority tended to be more organizational, even political. In short, it became the only game in town for study of human behavior from an evolutionary perspective. The alternatives—sociobiology and gene-culture co-evolution—had much less to offer in terms of research funding, career opportunities, or just an untroubled academic life.

Early years of evolutionary psychology

At first, the term ‘evolutionary psychology’ simply referred to psychologists and psychiatrists who shared an interest in evolutionary theory. Such people began to come together in the late 1980s:

In mid-1987, an initial list of people using modern evolutionary theory to address problems in psychology and psychiatry was compiled and distributed. The respondents suggested additional names that expanded the list to over 200 researchers. Many people expressed surprise that there were so many others working in the area. Many more suggested that it was time to organize a forum for the exchange of ideas and research findings in the area. (Evolution, Psychology and Psychiatry 1988)

The first forum was held at the 1988 Evolution and Human Behavior Meeting in Ann Arbor, Michigan. The meeting had two purposes:

- To facilitate the exchange of ideas and findings among researchers in the area of Evolution, Psychology and Psychiatry. The developing new basic science will be emphasized.

- To consider plans for initiating an organization that will promote research and scholarly exchange in the area of Evolution, Psychology and Psychiatry.

The proceedings only hinted at evolutionary psychology’s eventual divorce from sociobiology. Some presenters talked about a mismatch between current behavior and earlier contexts of adaptation, but these contexts were not placed over a million years ago in the Pleistocene.

It was decided to have more meetings and to hold them annually. The 1989 meeting, now called the Human Behavior and Evolution Conference, had a similar mix of ideas. Presenters were now talking more about ‘mismatch’ and ‘mental mechanisms’:

Debate about the relevance of mental mechanisms, rather than current human behavior, to the study of adaptation continued from other conferences in the recent past. […] Turke pointed out that studies examining current reproductive success could reveal the nature of mental mechanisms by comparing contexts in which humans do or do not behave adaptively. […] The abstract models presented by evolutionary psychologists (first by Cosmides and Tooby), which are somewhat like descriptive structural equation models, seem often to be misunderstood to present physiological structures, again making mental mechanisms appear to promote invariant behavior. More sophisticated basic theory is necessary to determine whether current behavior reflects adapted strategies. (HBES, 1990)

Leda Cosmides and John Tooby were already arguing that the genetic determinants of human behavior had assumed their current form long before the emergence of Homo sapiens, but this view was still a minority one. Other presenters were affirming the possibility of much more recent evolution:

Cultural versus natural selection was also the major topic of a roundtable on the final morning, lead by William Hamilton, George Williams, Irenaus Eibl-Eibesfelt, Edward Wilson, Irven DeVore, and Richard Dawkins. Much of the discussion focused on the unit of selection and the selective process. Dawkins stressed defining a specific replicating unit, which must be genes or memes. Williams proposed using epidemiological, disease–transmission models for the spread of cultural traits rather than using genetic models. Wilson stressed the importance of co-evolutionary theory, which models the interaction of genes and culture in epigenetic processes. (HBES, 1990)

Evolutionary psychology was nonetheless en route to becoming a paradigm distinct from sociobiology, with the Pleistocene EEA as the key difference. In 1989, this theme inspired two articles in Ethology and Sociobiology. Don Symons wrote:

[…] a well-formed description of an adaptation must consist solely of words for things, events, relations, and so forth that existed in the EEA, which, in the case of human beings, means the Pleistocene world of nomadic foragers. The specific environmental features to which Tibetan polyandry is adapted, according to Crook and Crook, include agricultural estates, animal husbandry, primogeniture, monasticism, aristocrats, landlords, governments, and taxation. Because none of these things existed in the human EEA, Crook and Crook’s account contains not a single well formed description of a Darwinian adaptation […] (Symons, 1989, pp. 138-139)

John Tooby and Leda Cosmides argued along similar lines:

It is no more plausible to believe that whole new mental organs could evolve since the Pleistocene—i.e., over historical time—than it is to believe that whole new physical organs such as eyes would evolve over brief spans. It is easily imaginable that such things as the population mean retinal sensitivity might modestly shift over historical time, and similarly minor modifications might have been made in various psychological mechanisms. However, major and intricate changes in innately specified information-processing procedures present in human psychological mechanisms do not seem likely to have taken place over brief spans of historical time. (Tooby & Cosmides, 1989, p. 34)

Here, Tooby and Cosmides assert that ‘whole new mental organs’ could not have arisen over the past million years. They then conclude that ‘major changes’ to mental organs are unlikely. This conclusion hardly follows from their initial assertion, which itself is doubtful. New organs have arisen over shorter time spans, specifically through duplication of an existing organ and rapid modification of the ‘spare.’

As a result of these articles and succeeding ones, the Pleistocene EEA came to define evolutionary psychology. The latter ceased to mean ‘sociobiology for psychologists’ and took on a narrower, more paradigmatic meaning.

Gene-culture co-evolution: a competing paradigm

At the turn of the 1990s, it was still far from clear that evolutionary psychology would take over from sociobiology. Gene-culture co-evolution seemed to hold a stronger position.

This other paradigm began in a cultural evolution class that L.L. Cavalli-Sforza taught in 1978-79 at Stanford to Robert Boyd and Peter Richerson (Stone & Lurquin 2005, p. 108). The Italian geneticist argued that the natural environment has not been the main driving force of human evolution. Instead, this role has largely fallen to the cultural environment, such as oral and written language, social organization, technology, means of subsistence, and so forth. There has thus been a feedback loop: we humans have created different cultural environments, which in turn have subjected us to different pressures of natural selection. Our creations have become our creators. This co-evolution fascinated Cavalli-Sforza, and its study now occupied his thoughts.

But others were thinking along the same lines, like the anthropologist Claude Lévi-Strauss in 1979:

[…] as anthropologists, the aspects of the question that will always appeal to us will be much less the genetic determination of culture or cultures than the cultural determination of genetics. […]

The selection pressure of culture—the fact that it favors certain types of individuals rather than others through its forms of organization, its ideas of morality, and its aesthetic values—can do infinitely more to alter a gene pool than the gene pool can do to shape a culture, all the more so because a culture’s rate of change can certainly be much faster than the phenomena of genetic drift. (Lévi-Strauss, 1979, p. 24-25)

The 1980s saw growing interest from other students of human evolution. Robert Boyd and Peter Richerson were among the first, followed by Pierre van den Berghe, Charles Lumsden, E.O. Wilson, and R.D. Alexander. The new paradigm was summed up by Pierre van den Berghe:

[…] the causality between genes and culture is reciprocal […] culture, though clearly possessing some emergent and irreducible properties (notably in its mode of transmission), is itself subject to a wide set of developmental parameters because it comes out of a brain with a definite bio-chemical structure […] the human mind, despite its undoubted plasticity, is not a tabula rasa. It is predisposed to learn certain things with ease, and others with difficulty or not at all. According to this viewpoint, the programmed learning biases of the human brain result in a non-random distribution of cultural products […] Moreover, since culture has consequences for the survival and reproduction of flesh and blood organisms, natural selection must exert some influence on cultural evolution (van den Berghe & Frost, 1986)

Work on gene-culture co-evolution initially involved trawling through the ethnographic literature. In the mid-1980s, however, a major project for field research was launched, specifically among the Inuit of northern Canada.

Its leader? Cavalli-Sforza. The project was organized in 1986 with professors from Queen’s University and Université Laval. The aim was to determine whether natural selection favors different mental toolkits in hunting and gathering societies versus agricultural societies. As one project member, John Berry, a psychologist at Queen’s University, later explained:

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)

According to an unpublished report, Cavalli-Sforza wished to trace the origins of Inuit artistic talent by estimating the relative contributions of genetic endowment and socio-cultural learning:

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 approach would be to study specific Inuit artists and then their biological and non-biological relatives. The high rate of adoption among Inuit (between 15 and 30%) would provide a means to distinguish cultural inheritance from genetic inheritance in the transmission of artistic talent. Related mental traits would also be investigated. “Given enough information one can hope to separately estimate two quantities, called respectively cultural and genetic heritability” (Berry & Cavalli-Sforza 1986, p. 5)

The project fell through. At Laval, we assumed something went wrong with the funding. At Queen’s, the story was that Cavalli-Sforza had quit because of illness. Yet his biography makes 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 (Stone & Lurquin, 2005, pp. 98, 160). In any case, ill health would have been a reason for postponing the project, not canceling it.

This project has left no traces in any of Cavalli-Sforza’s publications—books, journal articles, conference proceedings, or poster sessions. The paper trail amounts to one unpublished report (Berry & Cavalli-Sforza, 1986). Just as mute are his published writings on gene-culture co-evolution. Examples are confined to the usual suspects: lactose tolerance in cattle-raising societies, and malaria resistance among tropical agriculturalists (Cavalli-Sforza & Cavalli-Sforza 2008, p. 264). There is no hint that natural selection might have favored different mental traits in different cultural environments.

Endgame

With Cavalli-Sforza gone, the field of gene-culture co-evolution lost momentum. It had big names, but few of them could put boots on the ground, i.e., do fieldwork. Nor could any of them focus on this area of research. As big names, they typically had their fingers in many pies.

There may have been another reason in the case of Cavalli-Sforza. He was vulnerable to blackmail because of his wartime anthrax research … in Berlin. Nothing terrible came of that laboratory work, but it had the potential to derail his career. At the very least, it was a stain on his curriculum vitae. (1)

Evolutionary psychology thus beat out its rivals by default. The term ‘sociobiology’ was becoming a mark of Cain even among people interested in human behavior and evolution. In 1997, it was literally voted out of existence. Gene-culture co-evolution continued to attract interest but only as a sideline.

With its rivals growing ever weaker, evolutionary psychology gained strength as the millennium drew nearer. It could now offer grad students a hassle-free research environment with a real chance of academic employment later on. This may have been due to avoidance of the stormy issue of population differences (although academia in general was becoming calmer). A bigger reason, however, was the strong focus of its main proponents, John Tooby and Leda Cosmides. They talked at conferences, gave interviews to the media, networked, and published, published, published. As they slowly climbed the academic career ladder, they would turn around to help likeminded people on lower rungs.

Bit by bit, they did what the big names could not do. They created a new teaching and research environment. And this environment would be called ‘evolutionary psychology.’

Note

1. Whenever Cavalli-Sforza lists his publications he never goes farther back than 1947. His wartime publications are all the more unknown because they were published under the name of Cavalli. He later changed his name to Cavalli-Sforza, having been ostensibly adopted by the second husband of his maternal grandmother. His autobiography dates the name change to 1950 (a year after his father died) when he was 28, married, and already a father. Such circumstances hardly justified adoption under Italian law or custom. Even more inexplicably, he was still publishing under his old name as late as 1953. Google Scholar lists three publications by L.L. Cavalli in 1950, one in 1951, five in 1952, and two in 1953.

References

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.

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

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

Evolution, Psychology and Psychiatry. (1988). Meeting Announcement, Ann Arbor, Michigan, October 28-30, 1988.

HBES. (1990). Summary of the first Human Behavior and Evolution Conference: Evanston, Illinois, August, 1989, Human Behavior and Evolution Society Newsletter, 1(1), 2-4, July 1990.

Lévi-Strauss, C. (1985). Claude Lévi-Strauss à l’université Laval, Québec (septembre 1979), prepared by Yvan Simonis, Documents de recherche no. 4, Laboratoire de recherches anthropologiques, Département d’anthropologie, Faculté des Sciences sociales, Université Laval.

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.

Symons, D. (1989). A critique of Darwinian anthropology, Ethology and Sociobiology, 10, 131-144.

Tooby, J. and L. Cosmides. (1989). Evolutionary psychology and the generation of culture, Part I. Theoretical considerations, Ethology and Sociobiology, 10, 29-49.

van den Berghe, P. L. & P. Frost. (1986). Skin color preference, sexual dimorphism, and sexual selection: A case of gene-culture co-evolution? Ethnic and Racial Studies, 9, 87-113.

Rapid cultural evolution: the case of the Iroquois

Cahokia, an Amerindian town on the Mississippi of 10,000 to 20,000 people. A forerunner of what might have been?

Native Indian societies are widely seen as unchanging before Europeans came into the picture. This view sometimes has almost religious overtones. Amerindians lived in harmony with their world, and this harmony was broken by the White man.

Yet this view is at odds with a growing consensus among archeologists. Rapid cultural evolution was already under way in eastern and central North America when the first Europeans arrived. Had their arrival been postponed long enough, they would have encountered millions of sedentary Indians in a zone stretching from the lower Mississippi to southern Ontario. A northern Aztec Empire.

The northern end of this zone experienced the most rapid change. Nomadic hunter-gatherers roamed over southern Ontario and New York State until late in prehistory. Then, some time after 500 AD, these Iroquoian-speaking peoples began to settle into villages and cultivate corn, beans, and squash.

After a slow start, this cultural evolution began to accelerate circa 1300 AD. The result, according to anthropologist Bruce Trigger, was “a dramatic revolution in Iroquoian life”:

[…] Houses became longer and were inhabited by many more families. The length of the houses varied greatly. They were located closer together and began to be aligned parallel to one another in groups that may have been occupied by related matrilineages or individual clans. Villages were surrounded by more elaborate fortifications, and at least some of the village planning may have been intended to reduce the amount of palisades that had to be constructed and manned in order to defend a settlement (Noble 1969:19). Higher frequencies of house extensions and of interior house post densities suggest that individual houses were being occupied for longer periods than previously. This would also have encouraged sturdier construction. (Trigger, 1985, p. 92)

These changes in material culture went hand in hand with an increase in social complexity:

In New York State cultural groupings ancestral to the historical tribes of that region - including the Five Nations Iroquois - also become more clearly defined. […] In all these areas many communities continued to increase in size, probably mainly as a result of the union of two or more existing ones. Many settlements had 1,500 inhabitants. While houses became shorter, they still differed considerably in size. Village planning became more elaborate, with open spaces being provided as work areas and for the disposal of garbage. (Trigger, 1985, p.100)

The increase in social complexity brought changes in political organization:

[…] There is also widespread evidence at this time of neighbouring and hitherto autonomous settlements clustering close to one another to form "tribes." The best documented example is Tuck's (1971:214-16) demonstration that two villages, one small and the other much larger, settled within a few kilometres of each other between AD 1450 and 1475 to found the Onondaga nation. The larger village was itself the result of an earlier fusion of two small ones. This drawing together of communities to form larger settlements and tribes led to the abandonment of many formerly settled areas and produced more widely separated clusters of human habitation. It also created new political groupings, each of which embraced more people than any previous ones in this part of North America had. (Trigger, 1985, p. 102)

There were also ideological innovations that may have come from places farther south, such as the ritual killing of prisoners of war:

Certain key elements, including the use of prisoners, the removal of the heart, the killing of the victim on an elevated platform and in view of the sun, and finally the cooking and eating of all or parts of his body, connect this northern Iroquoian ritual with ones practised in the southeastern United States and in Mexico by the Aztecs, although many specific differences remain. (Trigger, 1985, p. 97)

Finally, there was an intensification of warfare that began before the arrival of European traders or settlers:

There is now also much archaeological evidence of warfare after AD 1400 between Iroquoian groups in the London area and the Fort Meigs culture, found in extreme southwestern Ontario and around the western end of Lake Erie. […] Hence the warfare between the Neutrals and the Central Algonkians which continued into the 1640s might have been the final stages of a conflict that had begun in the prehistoric period. (Trigger, 1985, p. 107)

Trigger concludes that these processes of State formation and militarization were endogenous:

[…] archaeologists may have oversimplified the late prehistory of the Iroquoian peoples and underestimated the dynamism of their cultural pattern and its capacity to generate new forms of creative and destructive behaviour. The Iroquoians now seem to have evolved the essential features of their way of life before the first Europeans appeared along the east coast of Canada. (Trigger, 1985, p. 108)

This cultural evolution was actually accelerating when the Europeans arrived. What if their arrival had been postponed? The Iroquois would have certainly surpassed the mound builders of the Mississippi valley and probably reached a level of civilization like that of the Aztecs.

Such a scenario almost did happen. Indeed, conditions were far from ideal when the English and the French began to settle North America. Western Europe was just returning to the population levels that had existed before the Black Death. The North Atlantic was entering a cold period, called “The Little Ice Age,” that made trans-oceanic crossings difficult. Finally, the Turks were pushing deep into Central Europe, laying siege to Vienna in 1529 and 1683 and vowing to drive on to Cologne.

Had this fragile context taken a turn for the worse, there might have been insufficient will or ability to colonize the Americas. European settlers would have perhaps arrived on the Eastern Seaboard only in the late 1700s.

And beyond the Appalachians, they would have found millions of sedentary Amerindians living in fortified cities and recently united under the aegis of the Iroquois Confederacy …

Reference

Trigger, B.G. (1986). Natives and Newcomers: Canada's "Heroic Age" Reconsidered, Montreal: McGill-Queen's University Press.

Continent orientation, cultural evolution, and the Amerindian exception

Pre-Columbian copper artifacts from Illinois, Oklahoma, Missouri, and Illinois.

In my last post, I criticized Jared Diamond’s theory about continent orientation and cultural evolution. This theory posits that people, and hence ideas, are likelier to circulate along an east-west axis than along a north-south one. This is because people tend to move about in environments that have similar climates and ecosystems. Eurasia has thus reaped the benefits of having a belt of societies—stretching from Spain to Japan—that can borrow new ideas from each other with relative ease.

This is not the case with sub-Saharan Africa, which is oriented north-south. It has a much more limited pool of ideas to draw upon. Diamond argues that this is one big reason why sub-Saharan Africans failed to develop beyond the stage of simple agricultural societies.

But what about the Americas? Aren’t they even more north-south oriented? How, then, did advanced civilizations develop in Mesoamerica and the Andes? And why did they develop even faster than ancient civilizations in Eurasia?

These were the questions I raised in my last post. Here, I’ll argue that this fast pace of cultural evolution was not limited to Mesoamerica and the Andes.

Take the transition from hunting and gathering to agriculture. Around 100 BC, agriculture was still confined to the American southwest. The rest of the present-day United States was home to nomadic hunter-gatherers. By 800 AD, agriculture had spread throughout most of the central and eastern U.S. and into southern Ontario. By 1000, the Mississippi valley had urban centers that were each built around a central plaza with earthen temple mounds. These developments were accompanied by a suite of cultural innovations: skilled metalworking; food storage in pits and cribs; timber palisades and bastions; and formation of intertribal confederacies.

This pace of change was, if anything, faster than comparable change elsewhere in the world. There is little evidence that the availability of new ideas was a significant brake on cultural evolution in the Americas—at least no more so than in Eurasia, where new ideas were supposedly more available. Agriculture, for instance, took more than five thousand years to spread from the Middle East to northern Europe.

Indeed, there is evidence of ancestral Amerindians having access to useful ideas that they nonetheless chose not to use. The wheel, for instance, was known to the Aztecs, who used it for toys. But they never used it for anything else.

Another example is copper working. This metal had been worked in eastern North America since at least 5,000 BC, and the resulting artifacts were “far larger and better shaped than any known native copper objects from the Middle East” (Smith, 1968, p. 242). Yet there was never any melting, smelting, casting, or alloying of copper. In particular, there was no attempt to harden copper by combining it with tin, lead, antimony, or arsenic, although such elements were available in the Americas. Such possibilities were there for the taking, but there was apparently little interest in doing so.

As Ehrhardt (2009) comments, “It is provocative and useful to think about why North American metal working technology did not follow the same developmental paths documented for other New World metal working industries.”

One factor may have been the overwhelming use of copper for status or ritual purposes, i.e., ornamentation that did not require hard metals (Ehrhardt, 2009). While such purposes certainly prevailed in Old World civilizations, the latter also used metalworking to make functional objects like kitchenware and tableware. Perhaps New World civilizations suffered not from a lack of ideas but rather from limits on the use of ideas. Mental innovation was subordinated to the interests of the ruling caste. The needs of ordinary folk came a distant second.

Thus, the availability of new ideas is not the main brake on cultural evolution. What matters more is the perceived usefulness of those ideas, and the people who decide which ones are useful and which are not.

Further thoughts

Why did cultural evolution follow a more fruitful path in the Americas than in sub-Saharan Africa? The latter had more opportunities for east-west exchange, being next to Eurasia and its cultural innovations. According to Diamond’s theory, cultural evolution should have been faster in sub-Saharan Africa than in the Americas. Yet the reverse happened.

How come? The main reason was that Amerindian men and women had to plan over a predictable yearly cycle. The men also had to provide for their mates and children, especially in winter—an obligation that not only integrated father, mother, and children into a single unit of family production but also freed the mother to specialize in other tasks, like garment making, food processing, and home building.

These factors pre-adapted Amerindians for later cultural evolution. The “family workshop” of nomadic hunter-gatherers became a model for the economic and political structures of sedentary farmers.

References

Diamond, J. (1997). Guns, Germs and Steel: The Fates of Human Societies, New York: W.W. Norton.

Ehrhardt, K.L. (2009). Copper Working Technologies, Contexts of Use, and Social Complexity in the Eastern Woodlands of Native North America, Journal of World Prehistory, 22, 213-235.

Smith, C. S. (1968). Metallographic study of early artifacts made from native copper (pp. 237–252). Warsaw: Actes du XIe Congrès International d’Histoire des Sciences VI.