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Evolutionary Psychology


Evolutionary psychology is a field of inquiry based on the idea that our evolutionary past, as represented in our current genome, affects how we think and behave in the present. Here are some points to clarify what an evolutionary psychologists, in my view at least, believes and what she or he does not believe—

  • Nature vs. Nurture. These are inseparable. Think of two identical kernels of corn and two identical peas. Place each in a separate pot of soil. Water one corn and one pea barely enough to keep them alive. Water the other two enough to let them flourish. Now a month later you will have four very different looking plants. Which was more important, nature or nurture? Evolutionary psychology does not maintain that evolution is everything and culture counts for nothing. It is meaningless to talk of the two separately. We evolved to be cultural beings. Our genetics doesn't really get expressed fully except in a cultural context.
  • Evolutionary Time Frames. Evolution occurs when there is a trait in the population that (1) varies within the population, (2) affects the reproductive success of bearers of the trait and (3) is inheritable. The time frames over which these evolutionary changes become obvious tend to be long compared to the life span of a single individual, on the order of hundreds or thousands of generations, depending on the magnitude of the differential reproductive success.
  • Evolution Is Not Self-Aware. When speaking of evolution, there is a temptation to anthropomorphize evolution and speak as if evolution had self awareness and intent. For example, it is tempting to say something like "Evolution gave us the ability to stand upright so that we could better see over the tall grass in the savannas of Africa." This sounds as if evolution has intent. A less misleading way to phrase this would be "During the time that our early ancestors were inhabiting the savannas of Africa, it is possible that there was a differential reproductive advantage favoring individuals that stood more upright since they could more easily see over the tall grass."
  • Evolution Cannot See the Future. This point is related to the previous point. Along with awareness, there is a tenancy to speak as if evolution can see the future. For example, you might hear someone say "Evolution prepared our species well to build and use tools such as electron microscopes and spaceships." Evolution is incapable of doing any such thing. Any ability we have to develop and use advanced technology is an accident of evolution. Evolution cannot anticipate and prepare for the future. Evolution is not a benevolent caretaker, guiding and looking out for the future of the species. Evolutionary history is replete with examples of species that were dead-ends, that went extinct.
  • Organisms Need Not Be Explicitly Aware of What They Are Doing. A cat follows the laws of physics, aerodynamics and physiology when it jumps from the sofa to a shelf, but no one is suggesting that cats have explicit and conscious theories in these scientific fields. That information is encoded implicitly in their bodies and their nervous systems. A mouse mother is following mathematical models of lifetime reproductive optimization when she decides whether to raise her young (maximizing current reproductive success) or eat them (maximizing future reproductive success), based on such factors as her age, the probability that predators will get to her litter, her current physiological condition, and current food availability. Again, no one is suggesting that every mouse mother thinks this through and comes up with the same mathematical model as every other mouse mother. Likewise, humans may be making strategic decisions of which they are not conscious. Of course it gets complicated with humans because we may be making conscious decisions or we may be making instinctual decisions, or more likely some funky combination of the two.
  • No "Just So" Stories. Rudyard Kipling wrote a collection of delightful stories where he explains various natural phenomena, such has why the rhinoceros is so grumpy (spoiler alert - it involves a tailor, cake crumbs and a removable skin). It is relatively easy to come up with post hoc, plausible explanations for various human behaviors based on known or supposed aspects of our evolutionary past. It is much, much more difficult to obtain evidence supporting or refuting such "just so" stories. We need more scientists making and testing falsifiable hypotheses.
  • It Is Possible to Test Evolutionary Psychology Hypotheses. You test hypotheses concerning evolutionary psychology the same way you test any scientific hypotheses—you formulate a hypothesis, you make predictions based on that hypothesis, then you gather data relevant to those predictions. If the data are consistent with the hypothesis, then you become a little more comfortable with the hypothesis. If the data contradict the hypothesis, then you move on to a different hypothesis. Note, you can falsify an hypothesis, but not prove a hypothesis (see Carl Popper).

So why does evolutionary psychology interest me so? About 60 million years ago our ancestors were small creatures scurrying about the forest floor, trying to avoid being stepped on or eaten. It is not known how social these creatures were, but from at least 30 million years ago, our ancestors were highly social. That's a lot of evolutionary time to spend in groups—fighting, bickering, loving, jockeying for position, wielding power, forming alliances, murdering, stealing, waging war, making friends, helping others, back-stabbing, raising children, dying, morning our dead. All these behaviors have been documented in our close relatives, the chimpanzees, gorillas, orangutans, and even our slightly more distant cousins such as baboons, so it's reasonable to assume that our ancestors were engaged in these behaviors and it's highly like that at least some of our current behaviors are influenced by our evolution in groups. OK, above I said no "Just So" stories so lets call the following hypotheses. Do we cut people off on the freeway due to some misplaced instinct to maintain our pecking order in the tribe, even though the people we cut off are strangers we are unlikely to see again? Can the fact that young women sometimes abandon their babies in dumpsters be interpreted within the context of lifetime reproductive maximization theory? Are there different mating strategies hardwired into our brains (promiscuity/monogamy/others?) based on our current evaluation of our social standing and relative probabilities of success with each of these strategies. How would you test each of these hypotheses?