January 16, 2007
History Denied: The Central Failure of Evolutionary Psychology
One of the major premises of evolutionary psychology is that if any human behavior pattern is universal across cultures, the behavior pattern is most likely derived from Darwinian evolution, i.e., from biological evolution by natural selection.
It's an interesting idea, and considerable effort has been expended to find such behavior patterns and construct Darwinian explanations for them. Since Darwinian evolution can only work across enormous ("geological") time scales, which means nothing much has probably happened in the way of Darwinian human evolution during the past 100,000 years, the focus of such explanations of universal behavior patterns across cultures is the struggle for existence of the human species during the Pleistocene era.
On close examination, it becomes apparent that the central failure of evolutionary psychology as an effort to understand human behavior is that it essentially ignores two important corollaries of this major premise concerning universality of behavior across present-day cultures. The first corollary is that any behavior pattern that is NOT universal across cultures is NOT derived from Darwinian evolution, but probably derived from cultural evolution plus individual learned experience. The second and more important corollary is that any behavior pattern within a culture that is not universal across decades, or generations, or centuries, or even millennia is also NOT derived from Darwinian evolution, and more likely derived from cultural evolution plus individual learned experience. On these small time scales, Darwinian evolution just doesn't have enough time to work and cannot be responsible for any behavior changes within a culture.
Thus the central failure of evolutionary psychology is the failure to recognize that universality across both time AND geography are necessary to identify a behavior pattern derivable from Darwinian evolution.
Let's consider some concrete examples. We all understand that the "old brain", the primitive part of the brain involved in basic drives such as hunger, thirst, and sexual pleasure (e.g., the hypothalamus), is a region of the nervous system whose wiring is most certainly for the most part derived by Darwinian evolution, probably going back to animals more primitive than mammals. Every human being is constructed with a hunger drive, a need to relieve hunger once a state of hunger is recognized, but the way the hunger drive is satisfied varies between individuals, between groups, between cultures, across geography, and throughout written human history. What is universal is the drive, not the behavior, and since the behavior, in this case the manner of satisfying the hunger drive, is NOT universal, we conclude this behavior is NOT derived from Darwinian evolution.
A similar observation can be made about the drive for sexual pleasure. The drive itself is most certainly derived from Darwinian evolution, the anatomy and physiology of sex are derived from Darwinian evolution, but the myriad ways in which the sex drive can be satisfied -- never universal across geography and history -- are NOT derived from Darwinian evolution, but are instead products of cultural evolution plus individual experience.
For example: Between 1950 and 1970, a period of only 20 years, Americans changed their sexual behavior so radically that the change is known as the Sexual Revolution of the 1960s. Consider the important fact that if we want to understand this change, the last sensible place to look is Darwinian evolution. Twenty years, less than a generation, is not even time enough for a hiccup in the natural selection of genes. In general, evolutionary psychology can tell us almost nothing about changes in human behavior throughout written history.
And now a corollary of my argument: To the degree that evolutionary psychology operates as a discipline independent of history and archeology -- thus ignoring universality of behavior, or the lack of universality of behavior, across time -- to that degree the central failure of evolutionary psychology will not be remedied.
Dan Agin
ScienceWeek
dpa@scienceweek.com
http://scienceweek.com/editorials.htm