How We Believe_ Science and the Search for God - Michael Shermer [93]
A simple example of an epigenetic rule is one-trial learning—taste aversion being the most obvious example. Pairing a food or drink substance with violent nausea, for example, will produce an aversion to that substance for some time to come (red wine once did me in and for over a decade I could not drink even a small amount of it). This is an evolved mechanism for avoiding toxic foods—the learning needs to take place immediately in one trial—there is no margin for error, no time for a gradual learning sequence. Language is a much more complex epigenetic rule in which we all learn the language to which we are exposed as infants, but the basic rules of language were learned over the past hundred thousand years by our ancestors. Moving beyond basic ethological concepts of innate mechanisms, Wilson shows how genes and culture interacted in our evolutionary history in complex ways he calls gene-culture coevolution. Forget the nature-nurture debate with its artificially imposed percentages assigned to each component (for example, 40 percent genes, 60 percent environment). We are well past such facile delineations (a process that itself may be a product of an epigenetic rule that directs us to cleave a continuous nature into bivariate categories in order to simplify our complex world). Humans, says Wilson, are products of both biological and cultural evolution so inextricably interwoven that the two cannot be separated:
Culture is created by the communal mind, and each mind in turn is the product of the genetically structured human brain. Genes and culture are therefore inseverably linked. But the linkage is flexible, to a degree still mostly unmeasured. The linkage is also tortuous: Genes prescribe epigenetic rules, which are the neural pathways and regularities in cognitive development by which the individual mind assembles itself. The mind grows from birth to death by absorbing parts of the existing culture available to it, with selections guided through epigenetic rules inherited by the individual brain.
The fear of and fascination with snakes, so common in peoples around the world, is produced by an epigenetic rule with obvious survival significance. But how that fear of and fascination with snakes is uniquely expressed depends on the culture in which the individual was raised. Snake stories, myths, and narratives all differ, depending on the culture, but the focus on snakes themselves is hard-wired. Wilson shows how:
Some individuals inherit epigenetic rules enabling them to survive and reproduce better in the surrounding environment and culture than individuals who lack those rules, or at least possess them in weaker valence. By this means, over many generations, the more successful epigenetic rules have spread through the population along with the genes that prescribe the rules. As a consequence the human species has evolved genetically by natural selection in behavior, just as it has in the anatomy and physiology of the brain.
This line of reasoning leaves behind the pejorative accusations and false dichotomies of biological and environmental determinism, with extremists on the political left and right accusing each other of employing Darwinian models to justify certain social or political agendas. The epigenetic rules that guide gene-culture coevolution are so complex and interactive that such name-calling tells us as much about the name-caller’s agenda as that of the accused. Culture, says Wilson, evolves “in a track parallel to and usually much faster than genetic evolution.” But, he notes, “Then quicker the pace of cultural evolution, the