Darwinian Psychology, or really, any “Psychology” that claims to be science, will operate under the assumption that the human brain, as an organ, has arrived at its modern form through the process of evolution, which includes a certain amount of design through Natural Selection. It does not take that much additional sophistication to realize that the human brain is not only good at, but absolutely requires for typical functioning, a great deal of learning. Therefore, it is reasonable to assume that the typical human brain functions as it does because of information provided by the genes that were shaped by evolutionary forces and information provided via learning, from some combination of culture and personal experience, which by the way, could also be subject to Darwinian selection (and includes the behaviors generated by other human brains, which in turn, were subject to Darwinian selection).

A simplified model for the development of typical behavior in humans might include these elements:

1) Behavior that emerges no matter what because genes make that happen. If you want to go see some of that, sneak up behind a friend and poke them with a sharp object. They will let out a primal sound and jump. They didn’t need to learn that.

2) Behavior that would not be observed at all were it not for enculturation or learning in the individual. If you want to see some of that, check out the languages people speak. Regardless of how language itself emerges in individuals, one is not genetically programmed just to speak French. One learns one’s language, and the language one uses is a very important behavior.

3) Behavior that is only “normal” (normative in antro-speak) or “typical” when it develops as a combination of those two things (canalized learning). This is a bit harder to explore. Looking at language in a different way than above might be one. Another might be looking at individuals with an upbringing that deprived them of the usual cultural inputs, like some of the classic “wild child” examples.

(I’m avoiding defining what “behavior” is to allow this discussion to fit into one blog post!)

This is basic Evolutionary Biology. A lot of people think that what I just described is Evolutionary Psychology. If it is, then Evolutionary Psychology has broadened its mission considerably, which would be fine. But Evolutionary Psychology is more narrowly defined than this. Specifically, Evolutionary Psychology assumes the existence of “modules” in the brain, mainly in the cerebrum (but there is no reason for them to not involve other brain structures) that are distinct neural systems that allow individual humans to carry out specific behaviors. From Cosmides and Tooby’s Primer on Evolutionary Psychology:

We have all these specialized neural circuits because the same mechanism is rarely capable of solving different adaptive problems. For example, we all have neural circuitry designed to choose nutritious food on the basis of taste and smell – circuitry that governs our food choice. But imagine a woman who used this same neural circuitry to choose a mate. She would choose a strange mate indeed (perhaps a huge chocolate bar?). To solve the adaptive problem of finding the right mate, our choices must be guided by qualitatively different standards than when choosing the right food, or the right habitat. Consequently, the brain must be composed of a large collection of circuits, with different circuits specialized for solving different problems. You can think of each of these specialized circuits as a mini-computer that is dedicated to solving one problem. Such dedicated mini-computers are sometimes called modules. There is, then, a sense in which you can view the brain as a collection of dedicated mini-computers – a collection of modules. There must, of course, be circuits whose design is specialized for integrating the output of all these dedicated mini-computers to produce behavior. So, more precisely, one can view the brain as a collection of dedicated mini-computers whose operations are functionally integrated to produce behavior.

While some of these behaviors might be in some form general to mammals (or primates or vertebrates or some other taxonomic group) they only count as proper modules if they exist in humans as human-specific capacities that are adaptations each shaped by a particular “environment of evolutionary adaptiveness,” altered over time through natural selection, to function a certain way. To be very clear: The functioning of these modules is primarily determined by neural systems that are specified by genes that were, in turn, shaped by natural selection.

The gasp and jump behavior noted above would be a bad example of a “human behavior” for this sort of study because although there are certainly human aspects to it, it is mainly a more general behavior. Try it with your cat and see what happens. A great example from Evolutionary Psychology would be cheater detection. Even if the detection of “cheating” behavior might be found in non-human animals, humans seem to do this in unique human ways. One study that supports and exemplifies this (which I’m a bit familiar with because I helped with it) compared human ability to solve a basic logic problem under different conditions. Briefly, humans were given two different problems, both with the same underlying logic and with the same logically determined answer, but framed in very different contexts. In one setup, the humans were asked to solve the problem in the context of an esoteric filing problem that a file clerk might encounter. In the other context the humans were asked to evaluate the honesty of individuals trying to get a drink at a bar, from the point of view of the bartender. In both cases there would have been an exhaustive, multi-step solution (such as asking everybody for their ID no matter what, or looking in every single file folder to see if everything was filed correctly) but there was also a clear and unambiguous least-step most efficient solution (ask only certain people for their ID, or look in only certain file folders), and the test subjects were asked to provide that efficient solution. In the case of the filing problem, people were shown to be really bad at finding the solution. In the case of the more human problem, where subjects were being asked to asses the chance that people were lying, they did rather well. This suggests that humans have an ability, built into the brain, to handle lying and cheating by other humans. (Here is an example of a recent related study.)

Evolutionary Psychology says that humans evolved to do this during a period of “evolutionary adaptiveness,” living in social groups where detecting cheaters conferred a fitness advantage, or not doing so caused a fitness disadvantage. Moreover, this capacity exists as a brain “module” that develops in individuals by virtue of genetic programming, with the genes doing that developmental programming having been under selection during that period.

An alternative explanation … but still evolutionary and still scientific … might be that the ability to detect cheating emerged in individuals who, over their lifetime, experienced the need to do so and learned, and/or received from their culture through the processes of enculturation, the ability to do so. In this explanation there may well have been gene-level selection to facilitate some sort of data processing or reasoning, and perhaps most importantly, learning, without which individuals would not be very good at developing a cheating detection mechanism.

In both cases, one could say that there is a “mental module” … a neural structure in the brain that is good at doing some thing. In both cases one could say that the module emerged as part of the evolutionary process. Indeed, I regard the result of this and similar experience as very strong evidence that there are modules in human brains that are really good at doing certain things, and that are sufficiently specialized that they are also bad at doing similar but in some sense “unnatural” versions of the same thing. In an Evolutionary Psychology version, the module was mostly built neurologically because of genetically specified development. In a more general Darwinian Psychology, brains are selected (though evolutionary process) to be good at learning how to do this sort of thing.

One way to test this would be to raise a group of babies in a cultural environment in which it was not necessary to ever detect cheaters, but where day to day activities of import required being really good at file clerking. If Evolutionary Psychology is right and Darwinian Psychology is wrong, then the adults that emerge from that experience will test the same way on the previously described experiment (or maybe a little different, but the pattern would be the same). If Darwinian Psychology is right and Evolutionary Psychology is wrong, then when confronted with a test for cheater detection vs file clerking, the test subjects will excel at file clerking and be lousy cheater detectors.

It is possible, of course, that both things happen: there could be genetically determined human-unique modules AND a set of general learning capacities.

In fact, much of the better research in Evolutionary Psychology addresses the potential combination or overlap between these developmentally distinct explanations. A recent paper by Fessler et.al is a great example of this. The paper, “Weapons Make the Man (Larger): Formidability Is Represented as Size and Strength in Humans,” tests the idea that when assessing the degree to which one should regard a foe as formidable, humans narrow down their assessment into a generalized variable that is very likely to have emerged as a cognitive tool during our Old World Primate/Ape ancestry: Size. They conclude “… knowing that a man possesses a gun or a kitchen knife leads people to assess him as larger and more muscular. In conjunction with prior work, our studies thus provide strong preliminary evidence that the conceptual dimensions of size and strength are employed to represent relative formidability.” To me, that is an excellent example of a study of evolved human capacities, done by a team of researchers who call themselves “Evolutionary Psychologists,” which does not ignore, but rather incorporates, the most likely scenario for the evolution of the human mind; human brains are the product of millions of years of evolution and specific human capacities emerge as a conjuncture of innate abilities and drives (attention to “bigness”) and individual culturally mediated experiences (understanding of the artifacts of violence) combined and fine tuned by forces that are worthy of further exploration.

(I would note that the lead author on this study, Dan Fessler, would be one of the first authors I’d point someone to whom might be interested in reading some “good Evolutionary Psychology.”)

“Evolutionary Psychology” can be viewed as distinct form a more general “Darwinian Psychology” which simply says that the brain is shaped by evolutionary forces, or a “Behavioral Biology” that might derive from both human and non-human primate studies, which could assert that typical human behaviors are the result of an unspecified (but knowable) combination of evolved genetically determined capacities or drives, and learning. hese are very different ideas, but many people conflate or confuse them.

Brains evolved. Sometimes, when criticizing Evolutionary Psychology, as I’ve done now and then and as Rebecca Watson recently did, those who call themselves “Evolutionary Psychologist” react in an interesting way. They claim that the criticisms are unscientific. They may label the critics as “creationists” or “science denialists.” I some cases, a defender of the subfield may even resort to cherry picking among the perceived attacker’s prior writings to falsely show that they hold certain beliefs. This sort of reaction has been observed of others who undergo criticism by people who really do hold similar fundamental views, but who do not agree in total with a particular position. I wonder if this reaction is a human universal of some sort. Perhaps, even, a module. It would be interesting to see this developed as a research project.

Fessler, D., Holbrook, C., & Snyder, J. (2012). Weapons Make the Man (Larger): Formidability Is Represented as Size and Strength in Humans PLoS ONE, 7 (4) DOI: 10.1371/journal.pone.0032751

See also:

?EP: The fundamental failure of the evolutionary psychology premise

?EP: The fundamental failure of the evolutionary psychology premise

Is evolutionary psychology worthless?

Reason.tv: Stone Age Minds – A conversation with evolutionary psychologists Leda Cosmides and John Tooby