In these remarks I concentrate on the Steven Pinker’s misconceptions about cultural evolution, cultural group selection, and gene-culture coevolution.
The problems in his essay begin with the idea that mutations have to be random with respect to fitness for natural selection to occur. Since cultural evolution manifestly includes the inheritance of acquired variation (if I learn something interesting, I can teach it to others), defining natural selection in this way seems to exclude anything cultural from the effects of natural selection. This is illogical. The problem is quantitative not qualitative. Natural selection works on any pattern of heritable variation. When animals rely only their own exploration and trial and error learning to gain the knowledge and skills necessary to survive, then the products of their learning are not heritable. This is approximately the case in many species where social learning is absent or of marginal importance. But for humans, learning from others is very important. We inherit most of what we know from others. Human are a veritable cultural adaptive radiation based on information that has been passed down the generations by social learning.
When a culture includes complex technology, such as the ocean going canoes of Polynesians, or complex social institutions, such as the Polynesian ranked lineage system, most members of the population follow cultural “recipes” acquired from their elders. Natural selection can work on such cultural traits. Polynesians who sailed canoes that were badly designed or built were less likely to have left offspring or imitators. Communities that had faulty institutions were more likely to have disbanded due to environmental deterioration, social collapse, or conquest by competing groups. Of course, Pinker is right that individuals sometimes make deliberate innovations. But the products of an inventor’s ingenuity do not often supplant existing devices and techniques (1). It is not easy to improve on complex adaptations. Many religious innovators preach a new doctrine for every Joseph Smith whose teachings led to the formation of Mormonism. In human culture, non-random variation and natural selection can both play roles in the evolution of cultural variation so long as the effects of non-random variation are not so strong as to overwhelm the transmitted aspect of culture.
Moderate rates of non-random innovation and natural selection together have a neat synergy in cultural evolution. In a population trying to exploit a new environment, no one yet knows what the best practices might be. In these circumstances, natural selection cannot act because there are no adaptive variants to select. Given enough time, adaptive variants will eventually emerge at random. But suppose a few innovative members of the population introduce fitness-enhancing variation at a faster, but still low, rate compared to random variation. Such a non-random process provides useful cultural variants so that selection can act sooner than if had to wait for random variation to produce adaptive variants.
Natural selection is a slow and painful process, even if it gets a boost from non-random innovation. In the case of culture non-natural selection based on innate or cultural biases can act to pick out favorable cultural variants. If such biases have evolved under the influence of natural selection, they will often act in the same direction natural selection would act. Biased learning or teaching thus also speeds up the cultural evolution of adaptations relative to what natural selection could achieve by itself, even including non-random variation. The human capacity for culture creates a system that ties decision-making to inheritance. This provides humans with a great advantage by speeding up the adaptive process without expecting individual innovators and innovation adopters to perform cognitive miracles. The evolution of cultural variants can lead to complex adaptations much faster than the evolution of genes alone because the work of creation and diffusion of favorable variants is distributed among many minds. Colleagues and I elsewhere argue at greater length than is possible here (2) that Pinker’s view of culture depends on an impossibly high degree of individual cognitive prowess that amounts to a magical “skyhook” in Daniel Dennett’s (3) felicitous phrase. Even if natural selection plays a subordinate role, as Darwin believed it did in “civilized times” (4), a rich formal theory of cultural evolution (a theory of history in other words!) has been built on the framework of combining non-random innovation, selective innovation adoption, and natural selection (5, 6).
Natural selection on large scale patterns of cultural variation is plausible because the cultural variation between neighboring groups that might compete is typically much larger than the genetic variation between the same groups (7). The reasons are not hard to see; all human groups are more or less open to immigration. Groups intermarry and intermarriage is a very effective conduit for genes. This is less true of culture. Because culture evolves more rapidly than genes, groups will continue to differ despite migration. A large body of social psychology research has characterized the active mechanisms that damp down variation within groups and protect between group variation from the effects of migration. Human social groups are psychologically very salient entities (8) as Pinker acknowledges. Groups often have different norms and institutions. Being able to conform to local norms and institutions is important for individual success, because institutions include carrots and sticks encouraging conformity to their dictates. Even individuals who personally dissent may nevertheless obey the group’s rules. In many hunting and gathering societies, egalitarian norms prevent would-be dominant males from taking the resources of others or even hoarding resources they themselves have acquired. This has the effect of reducing individual selection within groups and making it easier for selection to act on any existing cultural variation between groups (9).
Not surprisingly, children are adapted to efficiently learn norms the norms of their group (10). Hence, immigrants, especially immigrant children, typically assimilate to the groups they or their parents join without appreciably diluting their host cultures. Infant chimpanzees raised as children, by contrast, are no more able (or willing) to acquire norms than language (11).
Darwin (4) proposed that tribal scale selection was important in “primeval times” in the evolution of pro-social “instincts” such as empathy and patriotism. We certainly have ample ethnographic evidence of such between-group competition (12). Such primeval selection might have been based mainly on cultural differences between groups as it has been in ethnographic times.
Contrary to Pinker’s argument, the evidence for other-regarding dispositions in humans extends beyond the results of the economic game experiments he mentions. On the experimental side, see Batson’s experiments testing his empathy-altruism hypothesis against purely individualistic alternatives (13). Humans routinely share useful information with their fellow group members and assume information given to them to be provided honestly and in good faith. The fact that we have complex adaptations such as language that facilitates such cooperative behavior suggests that it has a long history in our species (14).
It is interesting to consider what human life would be like if people were fundamentally selfish. Some individuals behave in ways that we characterize as “psychopathic” and this behavior has a devastating effect on the functioning of the groups they are part of (15). Psychopathy involves a lack of empathy and habitual disregard of norms. It is highly disruptive to the organizations psychopaths inhabit. On many accounts based on the behavior of chimpanzees (16), human psychopaths (perhaps 1% of living populations) rather resemble our last common ancestor with the apes (and the selfish egoists of the bare-bones economic and evolutionary theory that was influential in the latter part of the 20th century). Psychopaths themselves typically suffer because their excessively self-regarding behavior is checked by institutions. It is hard to see how human societies could function as they do if even a large minority behaved like psychopaths.
Robert Boyd and I have proposed that in the human species, a pro-social psychology arose by cultural group selection and gene-culture coevolution. Once our ancestors were taking some advantage of cultural transmission and evolution, simple social institutions would have become part of their adaptive repertoire, such as stable mating bonds that would have the effect of encouraging patrilateral as well as matrilateral kin interactions (17). Then, social selection within groups, operating through primitive social institutions, would have generated selection on genes in favor of Darwin’s pro-social instincts. In ethnographically known hunting and gathering societies, people who ignore social norms are shunned as mates; sexual selection based on conformity to norms would have been a very powerful force shaping the innate features of human social psychology. Many rounds of gene-culture coevolution would have eventually built living humans who, given the right norms and institutions, are capable of considerable feats of cooperation. Bowles and Gintis have proposed a different gene-culture coevolution scenario (18).
I am not aware of any writings of Pinker’s that confront the hypotheses and evidence for the importance of cultural evolution, cultural group selection, and gene-culture coevolution. By not giving culture a reasonable role in human evolution in the first instance, he falsely relieves himself of any need to deal with further evidence.
1. Petroski H (1992) The Evolution of Useful Things (Vintage Books, New York) p xi + 288.
2. Boyd R, Richerson PJ, & Henrich J (2011) The cultural niche. Proceedings of the National Academy of Sciences USA In press.
3. Dennett DC (1995) Darwin’s Dangerous Idea: Evolution and the Meanings of Life (Simon & Schuster, New York) p 586.
4. Darwin C (1874) The Descent of Man and Selection in Relation to Sex (American Home Library, New York) 2nd Ed p 868.
5. Mesoudi A (2011) Cultural Evolution: How Darwinian Theory Can Explain Human Culture & Synthesize the Social Sciences (University of Chicago Press, Chicago) p xv + 264.
6. Turchin P (2006) War and Peace and War: The Life Cycles of Imperial Nations (Pi Press, New York) p viii + 405.
7. Bell AV, Richerson PJ, & McElreath R (2009) Culture rather than genes provides greater scope for the evolution of large-scale human prosociality. Proceedings of the National Academy of Sciences USA 106(42):17671-17674.
8. Haslam SA (2001) Psychology in Organizations: The Social Identity Approach (Sage Publications, London) p xvi + 411.
9. Boehm C (1997) Impact of the human egalitarian syndrome on Darwinian selection mechanics. American Naturalist 150(supplement):S100-S121.
10. Chudek M & Henrich J (2011) Culture–gene coevolution, norm-psychology and the emergence of human prosociality. Trends in Cognitive Sciences 15(5):218-226.
11. Hayes C (1951) The Ape in Our House (Harper, New York,) p 247.
12. Otterbein KF (1985) The Evolution of War: A Cross-Cultural Study (Human Relations Area Files Press, New Haven CT) p 165.
13. Batson CD (2011) Altruism in Humans (Oxford University Press, New York) p vi + 329.
14. Richerson PJ & Boyd R (2010) Why possibly language evolved. Biolinguistics 4(2-3):289-306.
15. Babiak P & Hare RD (2006) Snakes in Suits: When Psychopaths Go to Work (HarperCollins, New York) p xv + 336.
16. Vonk J, et al. (2008) Chimpanzees do not take very low cost opportunities to deliver food to unrelated group members. Animal Behaviour 75:1757-1770.
17. Chapais B (2008) Primeval Kinship: How Pair-Bonding Gave Birth to Human Society (Harvard University Press, Cambridge MA) p xv + 349.
18. Bowles S & Gintis H (2011) A Cooperative Species: Human Reciprocity and its Evolution (Princeton University Press, Princeton) p xii + 262.