Thursday, January 17, 2019

Evolutionary Psychology or Cultural Group Selection? Or Both?

At his Internet salon for the discussion of ideas--Edge--John Brockman asks one question at the beginning of each year and then over a 150 smart people answer the question in short essays.  In 2014, his question was "What scientific idea is ready for retirement?"  The answer of Peter Richerson (a Professor of Environmental Studies and Policy at the University of California-Davis) was "Human Nature."  The answer of John Tooby (a Professor of Anthropology at the University of California-Santa Barbara) was "Leaning and Culture."

While Richerson and Tooby are both leaders in evolutionary science, they disagree in their view of the primary subject of human evolution.  As a leading proponent of Cultural Group Selection, Richerson thinks human evolution is fundamentally about the evolution of human culture.  As a leading proponent of Evolutionary Psychology, Tooby thinks human evolution is fundamentally about the evolution of human nature.

For Richerson, the concept of human nature clouds our understanding of human evolution by assuming a mistaken dichotomy of nature and nurture or nature and culture, in which nature is wrongly seen as prior to culture in both evolutionary and developmental time.  In fact, Richerson argues, the evolutionary evidence for stone tool technology going back millions of years and the developmental evidence for social learning beginning early in infancy indicate  that human culture is prior to human nature, and that cultural evolution has driven genetic evolution.

For Tooby, the concepts of human culture and human learning explain nothing, because the phenomena of culture and learning themselves require explanation.  The idea of culture in the social sciences is like the idea of protoplasm in cell biology.  Protoplasm was once identified as the substance that worked through unknown mechanisms to carry out the vital processes of the cell.  But this was only a confession of ignorance.  "Now we recognize that protoplasm was magician's misdirection--a black box placeholder for ignorance, eclipsing the bilipid layers, ribosomes, Golgi bodies, proteasome, mitochondria, centrosomes, cilia, vesicles, sliceosomes, vacuoles, microtubules, lamellipodia, cisternae, etc. that were actually carrying out cellular processes."  Similarly, Tooby argues, the idea of culture needs to be replaced with a map of the evolved cognitive and motivational programs in the brain (the "organelles") that actually carry out our mental functions.

Despite the apparent opposition between these two positions, a careful study of the debate here reveals the underlying compatibility of cultural group selection and evolutionary psychology.  We need a science of human evolution that explains the complex coevolutionary interaction of human nature and human culture, which was originally proposed by Charles Darwin himself.

The proponents of gene-culture coevolution--the idea that human genes and culture are equally important in the human coevolutionary system--see support for this in Darwin's writings.  They even see Darwin as using his understanding of cultural evolution as the model for organic evolution (Mesoudi, Whiten, and Laland 2004; Richerson and Boyd 2010).  Friedrich Hayek made the same point--that Darwin's theory of biological evolution was the application to biology of the idea among the Scottish philosophers that social order arose by the cultural evolution of spontaneous order.

The logic of Darwin's argument for evolution depends on three principles--variation, competition, and inheritance.  Evolution requires variation of characters.  It also requires that those variable characters compete in such a way that some characters are more advantageous than others in the struggle for life.  Finally, if those characters are inherited, then the more advantageous characters will tend to spread in subsequent generations; and the accumulation of those favorable variations will produce adaptive designs for survival and reproduction.  This same logic applies to both biological and cultural evolution.

Darwin saw this evolutionary logic in the cultural evolution of language.  In The Descent of Man, he observed:
"The formation of different languages and of distinct species, and the proofs that both have been developed through a gradual process, are curiously the same. . . . Dominant languages and dialects spread widely and lead to the gradual extinction of other tongues. . . . We see variability in every tongue, and new worlds are continually cropping up; but as there is a limit in the powers of the memory, single words, like whole languages, gradually become extinct.  As Max Muller has well remarked: 'A struggle for life is constantly going on amongst the words and grammatical forms in each language.  The better, the shorter, the easier forms are constantly gaining the upper hand, and they owe their success to their own inherent virtue.' . . . The survival or preservation of certain favoured words in the struggle for existence is natural selection" (1871, 1:60-61; 2004, 112-13).
The evolution of language shows the coevolution of biological instinct and social learning.  The human brain has evolved adaptations for learning language, so that once they reach the critical learning period for language, all normal human children learn whatever language they hear spoken around them.  As Darwin said, "every language has to be learnt," but "man has an instinctive tendency to speak" (1871, 1:55; 2004, 108).  Rather than separating instinct from learning, we need to see that language shows an instinct for learning.

Darwin saw a similar evolutionary logic in the cultural evolution of morality.  He thought that human morality could have evolved through four overlapping stages of instinctive and cultural evolution.  First, social instincts led early human ancestors to feel sympathy for others in their group, which promoted a tendency to mutual aid.  Then with the development of their intellectual faculties and their capacities for language and habit, they were able to formulate and obey social norms of good conduct that could be transmitted as social traditions and inherited habits.  Darwin also stressed the importance of tribal warfare in the development of morality: such contests spurred the development of the moral and intellectual capacities that allow individuals to cooperate within groups so as to compete successfully against other groups.  Thus, Darwin proposed what today would be called evolution by group selection.  "Ultimately," he concluded, "our moral sense or conscience becomes a highly complex sentiment--originating in the social instincts, largely guided by the approbation of our fellow-men, ruled by reason, self-interest, and in later times by deep religious feelings, and confirmed by instruction and habit" (2004, 121-22, 130, 155-58).

Darwin had no knowledge of genetics, and so he could not understand the genetic evolution of instincts.  Nor did he clearly formulate the modern concept of culture.  Nevertheless, evolutionary scientists today can see in Darwin's writings at least a rudimentary conception of what today is called gene-culture coevolutionary theory based on the complex interaction of genetic evolution and cultural evolution.

And yet, as indicated by the debate between Richerson and Tooby, evolutionary scientists seem to be split between those who stress the evolution of culture and those who stress the evolution of human nature.  One can see that split in the journal Behavioral and Brain Sciences in the debate over an article by Richerson et al. (2016).  But if one studies that debate carefully, one can also see that despite the apparent split, cultural group selection and evolutionary psychology are fundamentally compatible and complementary.  I also see here the need for a third level of analysis--the level of human individuals added to the levels of human nature and human culture.  We need to understand the evolution of human social order through the complex interaction of human natural history, cultural history, and biographical history.

The initial question raised by Richerson and other proponents of cultural group selection is how can we explain the evolution of cooperation in modern mass societies with huge populations of millions of people and in global social networks of exchange that encompass the entire Earth.  Throughout 99% of human evolutionary history, for millions of years, our ancestors lived in small bands of nomadic hunter-gatherers that might sometimes have met in tribes of no more than a few hundred people.  It was less than 10,000 years ago that some human beings moved into larger sedentary settlements and then with the development of agriculture there arose large cities with expanding populations.  We can explain cooperation in small foraging bands as based on the genetically evolved instincts for kin selection and reciprocal exchange among people in face-to-face relationships. But it's hard to see how these genetically evolved social instincts for cooperation in small groups of relatives and known individuals can sustain cooperation extended to millions or even billions of human beings who are not kin and not personally known to one another.  We still have the genetically evolved social psychology of our ancient foraging ancestors, because there hasn't been enough time for human beings to become genetically adapted to modern mass societies.

This has led Richerson and others (like Robert Boyd, Joseph Henrich, and Kevin Laland) to propose that we have become adapted for social cooperation in modern societies not by genetic evolution but by cultural group selection. So, for example, the cultural evolution of "Axial Age" universalistic religions beginning around 500 B.C.E. created ethical systems enforced by belief in eternal rewards and punishments by moralistic "Big Gods," which fostered cooperation among co-religionists living in expanded social orders (Richerson et al. 2016, 13).  Those living in religious groups that were successful in surviving,  in recruiting converts, and in promoting high birth rates among their members prevailed over other religious groups that were less successful.  The rapid expansion of Christianity in competition with pagan religions illustrates this cultural group selection of religions.

Proponents of cultural group selection argue that we can see the three principles of "Darwin's syllogism"--variation, inheritance, and competition--in cultural evolution through group selection.  1.  Human groups often vary culturally.  2. This cultural variation is transmitted vertically from generation to generation and horizontally within a group.  3. Success in intergroup competition is frequently determined by cultural differences, so that some cultural groups are more successful in survival and reproduction than competing groups.  The evidence for these three claims--as surveyed by Richerson et al. (2016)--is evidence for cultural group selection.

There is some evidence that the first two claims are true for some other animals, but not the third claim.  Chimpanzee communities, for example, show cultural variation that is transmitted by social learning.  To that extent, chimpanzees are cultural animals.  But while chimpanzee communities compete, there is no clear evidence that success in group competition is influenced by cultural differences, and therefore there is no cultural group selection among chimpanzees.  There is some evidence, however, that whale and dolphin species could satisfy all three principles of the Darwinian syllogism; and if so, they could show cultural group selection (Richerson et al. 2016, 57).

Against Richerson and his colleagues, John Tooby and Leda Cosmides have responded by arguing that human cooperation in modern mass societies can be explained through the instinctive adaptations to small-scale social life without any need for cultural group selection.  They write:
"The properties of individual carbon atoms allow them to chain into complex molecules of immense length.  They are not limited to structures involving only a few atoms.  The design features of our evolved neural adaptations appear similarly extensible.  Individuals with forager brains can link themselves together into unprecedentedly large cooperative structures without the need for large group-beneficial modifications to evolved human design.  Roles need only be intelligible to our social program logic and judged better than alternatives" (Tooby and Cosmides 2016, 42).
In particular, they argue that the ancient evolved instinct for exchange or trade in foraging bands can be extended to encompass modern networks of exchange in mass societies:
"The dazzlingly extended forms of modern cooperation we see today (Adam Smith's division of labor supporting globe-spanning trade) appear differentially built out of adaptations for small-scale sociality that modularly scale, such as exchange--rather than the marginal benevolence of Smith's butcher, brewer, and baker.  Evidence indicates that political attitudes toward welfare and redistribution reflect a specialized forager psychology of sharing for variance reduction (Peterson et al. 2012) and resource-conflict (Peterson et al. 2013).  Societies that attempted to harness general benevolence to organize institutions and production--the USSR, East Germany, China, Cambodia, North Korea, Cuba--were spectacular cooperative failures.  That they functioned at all depended on other scalable small-scale specializations--aggressive threats (conditional punishment), hierarchy, dominance, coalitions, and so forth" (Tooby and Cosmides 2016, 42).
Notice that Tooby and Cosmides reject the claim of Marxist anthropologists that ancient human foraging bands were societies of primitive communism, and so modern communism could be a revival of this original natural state of humanity.  Notice also that in rejecting this Marxist claim, they also reject Friedrich Hayek's claim that socialism's popularity comes from its atavistic appeal to the socialist instincts shaped in ancient foraging bands, and therefore that a modern extended order of liberal capitalism requires a cultural suppression of evolved tribal instincts.  In contrast to Hayek, Tooby and Cosmides agree with Adam Smith that "the propensity to truck, barter, and exchange" is natural for human beings, who engaged in exchange or trade even in their ancient foraging bands.

Tooby and Cosmides agree with Alan Page Fiske that "market pricing" is one of the four psychological models of social organization found universally in human societies, including prehistoric foraging bands.  Consequently, socialist societies that attempt to abolish or suppress "market pricing" must fail because this runs contrary to evolved human nature (Tooby and Cosmides 1992, 211-218).  Contrary to Hayek's argument, modern liberal capitalism satisfies some instinctive desires of human beings.  (I have written about this in some previous posts hereherehere, here, and here.)

"Market pricing" and trade among foragers are well illustrated by the Aboriginal Australians.  The whole continent of Australia was crisscrossed with trading paths, usually along waterhole routes.  Goods such as pearl shells, spears, stone axes, shields, boomerangs, and bamboo necklaces travelled by trade across Australia (Berndt and Berndt 1988).  For example, the Yir Yoront group on the west coast of the Cape York Peninsula (in the far north of Queensland) traded sting ray spears for stone axes.  The flat alluvial country of the Yir Yoront provided no suitable stone for axes.  The best stone for stone axes came from quarries 400 miles to the south, which came to them through long lines of trading partners.  The Yir Yoront had a surplus supply of sting ray spears, which are good fighting spears because the sting ray barbs break into fragments when they penetrate human flesh.  At the coast, where sting ray spears were plentiful, a man might have to trade a dozen spears for one stone axe head.  But a 150 miles south of Yir Yoront, closer to the stone quarries, one spear might be traded for one stone axe head.  People near the middle of this trading chain, who made neither spears nor axes, acted as middlemen who took a certain number of both as their middleman's profit.  The Yir Yoront men understood the laws of supply and demand and the gains from trade (Cosmides and Tooby 1992, 216-17; Sharp 1952).

It is true that foraging bands show communal sharing of resources--particularly, in the sharing of meat--which Marxist anthropologists have interpreted as a primitive form of communism.  But as Cosmides and Tooby indicate, this sharing is not general or indiscriminate.  Foragers share meat brought back to camp by hunters for "variance reduction."  Success in hunting wild game depends not just on skill and effort but also on luck.  Even good hunters often come back from a day of hunting without any meat.  To protect themselves against the risk of having no meat, successful hunters share their meat, with the understanding that when they are unsuccessful, they will be the beneficiaries of sharing.  But those who try to cheat--those who take the shared meat but never reciprocate by sharing the meat they have procured--are punished by expulsion from the meat sharing system.  As some anthropologists have noted, this is like a system of commercial insurance where losses are shared among many individuals to reduce the risk to each.  By contrast, the gathering of wild plants does not show such variance.  Those who make any effort to gather plants usually return to camp with some food.  Consequently, foragers share their plant food within their families but not with others outside the family (Cashdan 1989; Cosmides and Tooby 1992, 212-17).

Tooby and Cosmides think this evolved psychology for sharing to reduce variance in resources due to luck explains political attitudes about social welfare programs.  Modern social welfare institutions involving millions of people who are non-kin and personally unknown to one another are modern cultural inventions that did not exist in ancient foraging societies.  But the evolved human psychology for systems of exchange shaped in foraging societies is still manifest in the political opinions about welfare programs.  Around the world, people support welfare for needy individuals suffering from bad luck who are willing to find jobs; but people are less inclined to help individuals who are identified as cheaters or free-riders who do not deserve public aid (Peterson et al. 2012; Peterson 2015, 2016).

Sometimes Cosmides and Tooby imply that if they can explain the extended forms of modern cooperation (such as social welfare programs) through a specialized forager psychology (such as sharing for variance reduction), this shows there is no need for an explanation through cultural group selection.  But the proponents of cultural group selection have argued that evolutionary psychology and cultural group selection are not alternatives but rather complements.  The very possibility of cultural group selection depends on human beings having evolved instincts for learning culture.  And intergroup competition will favor those group-beneficial cultural traits--social norms, beliefs, and practices--that conform most closely to our evolved psychology (Henrich and Boyd 2016; Richerson et al. 2016, 49-50).  So, for instance, one could predict that social welfare programs that satisfy the evolved psychological propensity to punish cheaters will fare better than social welfare programs that frustrate this propensity.

Actually, even Cosmides and Tooby have admitted that evolutionary biology requires multi-level explanations that are complementary rather than contradictory.  They have observed: "In evolutionary biology, there are several different levels of explanation that are complementary and mutually compatible.  Explanation at one level (e.g., adaptive function) does not preclude or invalidate explanations at another (e.g., neural, cognitive, social, cultural, economic)" (Cosmides and Tooby 1997, 14).

Tooby's argument in 2014 that the concept of "culture" has no proper place in evolutionary science contradicts what he and Cosmides have written about cultural evolution.  They have said that "we are not abandoning the classic concept of culture" (Tooby and Cosmides 1992, 118).  They do propose, however, decomposing the traditional concept of culture into three kinds of culture (Tooby and Cosmides 1992, 121).  First, "metaculture" is their term for the cross-cultural regularities in human life that correspond to universal human nature, which make it possible for human beings to understand cultures beyond their own, without which cultural anthropology would be impossible.

Second, "evoked culture" arises when local circumstances trigger specific mechanisms of evolved human psychology in individual minds that create cultural representations without any transmission of cultural contents from other individuals.  They explain this through the metaphor of evolved humans as being like juke boxes identically designed with thousands of songs, and with devices designed to select songs on the basis of the juke box's location, time, and date.  (OK, I know that you young folks out there have no understanding of juke boxes, unless you've watched the cable TV reruns of Happy Days.)  This would create a global pattern of song cultures with cultural similarity within each group and cultural diversity between the groups.  This could generate the patterns of culture that we see without any social learning or transmission of culture from one generation to the next.  But they admit that "the juke box thought experiment is an unrealistically extreme case in which a complex, functionally organized, content-sensitive architecture internalizes no transmitted informational input other than an environmental trigger" (Tooby and Cosmides 1992, 117). Proponents of cultural group selection recognize evoked cultural responses to the environment as psychological switches that cultural group selection could harness (Henrich and Boyd 2016).

As I have indicated in a previous post, Tooby and Cosmides explain both socialism and capitalism as "evoked culture": socialism appeals to us today by evoking the evolved rules of sharing for risk pooling, while capitalism evokes the evolved system of cooperation through social exchange or trade.  Socialism fails because the rules evolved for sharing among small bands of hunters for which the rules were adaptive, but these rules are maladaptive for large modern societies in which people are interacting anonymously with thousands or millions of people.  Capitalism succeeds because the rules of the evolved cognitive system for social exchange can reach far beyond individual perception through the globally extended order of markets, and thus the evolved rules for social exchange can be adaptive both for small foraging bands and for modern mass societies.

The third form of culture recognized by Tooby and Cosmides is the "epidemiological culture" that is transmitted by social learning both within each generation of individuals and across the generations, which is a fundamental part of cultural group selection.

So Tooby, Cosmides, and the other evolutionary psychologists don't reject the idea of culture as such.  But they do reject the idea of culture if it is grounded on a "blank slate" view of the human mind that denies human nature--the idea that the human mind has no (or very little) content of its own except for whatever content has been imposed on it by the external cultural environment.  Richerson seemed to confirm that this fear of the "blank slate" version of cultural theory is warranted when he argued in 2014 that the concept of human nature should be discarded.

But then Richerson contradicts himself when he says that cultural group selection does not defend a "blank slate hypothesis," because cultural evolution is enabled and constrained by the universal human nature of evolved social instincts for learning (Richerson et al. 2016, 6, 49-51).

My conclusion from all of this is that an evolutionary science of social order requires a multi-leveled analysis of the interaction of natural history (evolutionary psychology) and cultural history (cultural group selection).

Even that is not enough, however, because we need a third level--biographical history (the evolved personality and life history of self-interested individuals who are agents of cultural change acting through coercion or persuasion).  In many animal groups, we can see how dominant individuals shape the social norms for the group.  For example, dominant macaques police conflicts in ways that protect their dominance while reducing conflict within the group (Flack et al. 2005, 2006).  This is surely true for human beings as well.  Consider, for instance, how the cultural history of the United States was altered by the dominant individuals in the American Continental Congress that drafted and signed the Declaration of Independence, or those in the Constitutional Convention who drafted and promoted the Constitution of 1787.  What we need here is an agent-based theory of how "self-interested agents create, maintain, and modify group functional culture" (Singh, Glowacki, and Wrangham 2016).

Part of this evolutionary biographical history would include the biological study of animal personalities and the individual psychology of cultural leaders--including moral, religious, political, and intellectual leaders.  Some of my posts on this can be found here and here.

In future posts, I will have more to say about applying cultural group selection and evolutionary psychology to Hayek's evolutionary science of capitalism and the liberal order.


REFERENCES

Berndt, Ronald M., and Catherine H. Berndt. 1988. The World of the First Australians: Aboriginal Traditional Life, Past and Present. 5th ed. Canberra, Australia: Aboriginal Studies Press.

Cashdan, Elizabeth. 1989. "Hunters and Gatherers: Economic Behavior in Bands." In Stuart Plattner, ed., Economic Anthropology, 21-48. Stanford, CA: Stanford University Press.

Cosmides, Leda, and John Tooby. 1992. "Cognitive Adaptations for Social Exchange." In Jerome H. Barkow, Leda Cosmides, and John Tooby, eds., The Adapted Mind: Evolutionary Psychology and the Generation of Culture, 163-228.

Cosmides, Leda, and John Tooby. 1997. "Evolutionary Psychology: A Primer." Center for Evolutionary Psychology, University of California, Santa Barbara.

Darwin, Charles. 1859. The Descent of Man. 2 vols. London: John Murray.

Darwin, Charles. 2004. The Descent of Man. 2nd ed. London: Penguin Books.

Flack, J. C., et al. 2005. "Social Structure, Robustness, and Policing Cost in a Cognitively Sophisticated Species." The American Naturalist 165: E126-39.

Flack, J.C., et al. 2006. "Policing Stabilizes Construction of Social Niches in Primates." Nature 439: 426-29.

Henrich, Joseph, and Robert Boyd. 2016. "How Evolved Psychological Mechanisms Empower Cultural Group Selection." Behavioral and Brain Sciences (2016): e40.

Mesoudi, Alex, Andrew Whiten, and Kevin Laland. 2004. Evolution 58: 1-11.

Peterson, Michael B. et al. 2012. "Who Deserves Help? Evolutionary Psychology, Social Emotions, and Public Opinion About Welfare."  Political Psychology 33: 395-318.

Peterson, Michael B. 2015. "Evolutionary Political Psychology: On the Origin and Structure of Heuristics and Biases in Politics." Political Psychology 36: 45-78.

Peterson, Michael B. "Evolutionary Political Psychology." In David M. Buss, ed., The Handbook of Evolutionary Psychology, 1084-1101.  2 vols. 2nd ed. Hoboken, NJ: Wiley.

Richerson, Peter, et al. 2016. "Cultural Group Selection Plays an Essential Role in Explaining Human Cooperation: A Sketch of the Evidence." Behavioral and Brain Sciences (2016): e30.

Richerson, Peter, and Robert Boyd. 2010. "The Darwinian Theory of Human Cultural Evolution and Gene-Culture Coevolution." In Michael Bell, Douglas Futuyma, Walter Eanes, and Jeffrey Levinton, eds., Evolution Since Darwin: The First 150 Years, 561-88.

Sharp, Lauriston. 1952. "Steel Axes for Stone-Age Australians." Human Organization 11 (2): 17-22.

Singh, Manvir, Luke Glowacki, and Richard W. Wrangham. 2016. "Self-Interested Agents Create, Maintain, and Modify Group-Functional Culture." Behavioral and Brain Sciences (2016): e52.

Tooby, John, and Leda Cosmides. 2016. "Human Cooperation Shows the Distinctive Signatures of Adaptations to Small-Scale Social Life." Behavioral and Brain Sciences (2016): e54.

Tooby, John, and Leda Cosmides. 1992. "The Psychological Foundations of Culture." In Jerome H. Barkow, Leda Cosmides, and John Tooby, eds., The Adapted Mind: Evolutionary Psychology and the Creation of Culture, 19-136.

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