Recent Evolution

The following is my second-week reaction paper from a Fall 2006 class, Biological Approaches to Political Behavior, taught by Professors John Hibbing and Kevin Smith.

Investigating recent evolution is the key to evaluating the Evolutionary Psychologists’ claim that all human behavior can be traced back to adaptations that would have served Pleistocene people well. If there has been genotypical and phenotypical evolution closer to the present than 10,000 years ago, we must wrest evolutionary psychology free from the Evolutionary Psychology paradigm and look for evolutionary linkages to Agriculture and Industrial Age behaviors.

Evidence for recent evolution is accumulating rapidly. Examples are the Northern European adaptation to lactose digestion, which enabled them to increase the nutritional rewards of animal husbandry; the development of malaria resistance, which helps enable survival in tropical and subtropical climates; and, on the behavior-related side, changing regulation of prodynorphin, a building block of endorphins that plays a role in modulating pleasure and pain, the formation of deep emotional bonds, learning, memory, and perception. A review of recent investigations notes about prodynorphin, “Many are speculating that prodynorphin may be one of the first genetic markers that truly demonstrates what makes us human.� What is interesting politically about prodynorphin is that it’s regulated differently in different parts of the world, showing one pattern of effects in Europe and East Africa and a different pattern in India and China. Could it be that emotional political appeals will one day be shown to work differently across population groups because their members process endorphin building blocks differently?

Establishing an impressive and convincing body of political implications for traits springing from recent evolution will depend on how many of the discoveries plausibly relate to behavior. The bone structure, skin color and hair texture differences discovered by Jonathan Pritchard and his colleagues may not seem at first glance to affect behavior. But the appearance differences they generate have been and still are important cues for separating the in-group from the out-group in political matters old such as tribal organization and recent such as national identity. The Evolutionary Psychology paradigm requires that causal arrows start in the Pleistocene and proceed along just one trajectory to the present, leading Evolutionary Psychologists to argue for the idea of a universal human nature. But if evolution did not stop 10,000 years ago and traits that can affect behavior have since then been subject to mutation and drift, there cannot be a universal human nature; rather, there may be several different natures that correspond with the genotypical and phenotypical variation found in the world’s populations. Beyond this criticism, there is the accusation from Buller that Evolutionary Psychologists are “temporally provincial� in focusing on just the past 10,000 years of human evolution (and then only our very limited knowledge of that time span), when we have been around for far longer than that and, one hopes, will remain here for an evolutionarily significant period of time in the future.

But it is not so much the 10,000-year time frame that is the problem, it is the 1,000-year time frame that Evolutionary Psychologists are not studying in enough detail. Blinkered by their fascination with the Pleistocene, they are not noticing evidence of how quickly evolution can move. David Reznick and his colleagues found significant adaptive phenotypic variation in guppies after just 18 generations, which translates to about 360 years of human development. We have available to us records of human political behavior going back much farther than 360 years. We should be looking for evidence of behavioral adaptation much closer to the present, which may help reclaim evolutionary psychology (small letters) from the Evolutionary Psychologists.