Evolutionary Psychology: Careful, some practitioners may be carrying a kitchen knife!

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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.

ResearchBlogging.orgIn 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

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In Search of Sungudogo by Greg Laden, now in Kindle or Paperback
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14 thoughts on “Evolutionary Psychology: Careful, some practitioners may be carrying a kitchen knife!

  1. I should mention that the image at the top of the post is from Dan Fessler’s paper, which, in turn, is in PLOS so you can access it readily.

  2. Interesting and informative article. Although, where you say
    ““modules” in the brain, mainly in the cerebellum (but there is no reason for them to not involve other brain structures)”
    I think cortex is meant where cerebellum is said. The cerebellum is largely sensorimotor, made of granule, Purkinje, and basket cells. Decision-making and problem-solving circuits are make largely of the pyramidal cells in the cortex (and the cells of the limbus system).

  3. Jay: Cerebrum. Damn autocorrect. Also, limbic, not limbus, but yes, part of the “limbic system” is cortical and related to all sorts of behavioral stuff and memory.

  4. Good article, I appreciate the explanation here.

    So, research that attempts to answer the question: “is this behavior characteristic innate or learned” totally make sense to me (although it strikes me that it would be pretty important to have a research sample that crosses social groups and cultures).

    What DOESN’T make sense to me is the assumption that evolutionary psychology seems to make, “our research shows this characteristic is innate (let’s call it mental module X), THEREFORE it must have been selected for by evolution”. (And then they go on to discuss/speculate about the evolutionary pressures that must therefore have influenced the development of that mental module.)

    I think this is the essence of PZ’s objection in his latest ?EP article (btw, you’ve linked the same article twice).
    If I’m understanding his article correctly, there are a variety of valid evolutionary explanations for why mental module X might exist:

    1. Mental module X held a selective advantage that was strong enough to be acted upon by natural selection.

    2. Mental module X was propagated through the population through genetic drift, since the evolutionary advantage wasn’t significant enough for natural selection to act upon.

    3. Mental module X was a side-effect of a different change in the brain (Mental module Y) that was strong enough to be selected for. (PZ didn’t mention this one, but it occurred to me, and I don’t see any easy way to rule it out.)

    PZ talked about why explanation 2 is more likely than explanation 1. I tossed in 3 just because that’s an option that occurred to me, and I don’t see any reason to rule that out as a valid hypothesis.

    Any thoughts? Does evolutionary psychology take (1) as a premise, or are there ways they can support this view against the alternatives?

  5. BradC: I haven’t even discussed the question of “adaptive” at this point. The side effect hypothesis is certainly one to consider.

    I’m pretty sure that PZ and I do not have the same exact approach to the question of adaptation. This is probably because he studies fish and I study humans and primates. Having said that, one does have to make an argument for something being adaptive to suggest that it is adaptive, and then, something being adaptive does not necessarily mean that it arose as it is (from something entirely different or even ‘de novo’ somehow) as the adaptation you see for the adaptive (selective, fitness related) reasons one might assume.

    This is definitely the subject of future writing by me. For now, I’ll just throw these two items into the mix:

    Evolutionary psychologists some years back proposed that there are certain clues one can use to suggest that something is an adaptation, and one of those was “complexity.” If a thing is complex, it must have arisen through selection because randomness does not lead to complexity. However, what we see as complexity might not really be adaptive complexity, but rather, the simple fact that living stuff is complex, so even a simple (hypothetical) adaptation is going to be embedded in complexity somehow. Also, it may be the case that some Evolutionary Psychologist have skipped a step: If complexity leads one to consider something adaptive, as a clue to suggest that one develop a hypothesis about it, fine. But to lead to concluding that it is adaptive is wrong.

    Second: Primates are generally pretty social and their social behavior clearly relates to individual fitness. But, sociality (and what one might call “culture” in some cases) emerges from a combination of factors inherent to the sociology and biology of the organisms and in some cases information passed on over time. This produces a very different milieu for potential adaptations to emerge. Using gene-behavior theory or even methods and applying that without modification to social and potentially cultural (where stuff is passed on behaviorally) organisms is not going to get you very far.

    In my view, understanding adaptive evolution of behavior of highly social and cultural beings is in its infancy right now. This is analogous to doing astronomy with nothing other than a set of binoculars. You can do it, but you can’t get very far, and you are not even seeing much of what is out there.

  6. It makes me uncomfortable that you state so categorically that brains and behaviour have evolved. It seems very reasonable to believe they have – as reasonable as it is to say that all life has evolved (and culture too) but it is not the kind of supposition (for psychology) that can be refuted. At least, I haven’t come across a refutable hypothesis that comes from this supposition.
    Evolutionary explanations of behaviour seem therefore to be intrinsically flawed if you offer them as scientific explanations. Personally, I don’t doubt that our minds evolved through natural selection, but I can’t see how to turn that conviction into evidence that would meet the standards of a scientific psychology.

  7. Graham, you need to be more specific about what you mean when you say “evolved.” A purely traditional gene-centric view requires that behavior that is linked in any way to genes, even if just through the fact that there is sensory processing, has evolved because evolution is simply the process of change over time of the distribution of gene variants in populations. By that definition you’ve made an error by seemingly saying that brains and culture have both evolved, because the gene-culture link is kind of iffy. If by “evolution” you mean “adaptive change through natural selection” than that is an entirely different level of question. For evolution generally, it is not hard to say that behavior has evolved. A hypothesis could be that if you raise members of one species in the social context of a closely relates species its behavior would resemble the host species, the null hypothesis being that genes do not influence behavior (these two species are genetically different) and along with that one would want to demonstrate that there are genetic differences related to physical development between the species (not just assumed, but identify the genes). For that we’ve got very good evidence, as chimpanzees have some different brain-related genes than humans, and chimps raised in human settings remain chimps (but of a humanized flavor to a small degree).

    More generally, there are myriad examples of behavioral variation across species of known phylgenetic relationship, and in some cases across populations within a species, showing behavioral variation that can be mapped onto measurable contextual variables. For instance among the mammals the social systems of deer, antelopes, cattle, various groups of primates, and carnivores are observed to vary across ecological setting in coordination with body size and other factors in ways that are pretty well understood. The day to day behavioral repertoires of all these mammals, including the more social and brainy ones (may primates) conforms with expectations, hypotheses have been tested, the literature is rich.

    When we get to humans we could invoke human exceptionalism and just say, as per the old Frank Zappa song, “It can’t happen here.” But we don’t.

    Having said all that, I’m not making any arguments here related to the question of telling whether a particular feature of human behavior is adaptive, and/or arose as an adaptation via natural selection. Like you say, it makes sense that such things are true and there are examples of likely adaptations. I’m just not talking about them here.

    Here is an important piece of context: This blog post was written to correct misconceptions (arising from people getting things wrong) that my prior criticisms of classic Evolutionary Psychology are made from the perspective that I don’t think evolution applies to humans. Nothing could be farther from the truth. So, here in this humble blog post I’m simply stating that we’re going with the evolution assumption, not making an argument to convince anyone of that.

    Good question, though.

  8. Heh. Strangely enough, I don’t consider a “gene-centric view” of evolution the “traditional” one – more the “modern” one, genes being merely the mechanism we’ve uncovered for understanding how selection pressures lead to changes. Even though the earliest discoveries in genetics were contemporaneous with the development of Darwin’s theory, the theory itself was developed without reference to any specific mechanism.
    Genetics is not the only possible mechanism that could underpin evolution and, especially in areas such as cultural evolution, may have no role at all (except in the minimal sense of enabling the evolution of wetware that is pliable enough to exhibit such change).

  9. Agreed, except that Darwin’s formulation included a thing that was to become genes, not a thing that was replaced with genes, in that a key component of his evolution (including natural selection) was that offspring resemble their parents +/-

  10. The problem with “genes” is that the closer we look, the more complicated they get. There are over 10,000 (some say over 50,000) papers published just about (tumor protein encoding) p53. Without even discussing the reemergence of Lamarckian epigenetics, genes are susceptible to allelic variation, splice variants, chromatin modification, post-transcriptional modification, post-translational modification, temperature-dependent activity, compartmental sequestration, interactions between the mitochondrial genome and the nuclear genome, side-group modification of proteins, a growing bestiary of small active RNAs and more.

    I attended a lecture at Berkeley in the early 90’s by Francis Crick and a question he posed to the audience was “What is a gene?” I think the intervening 20 years have only made the answer more difficult.

    I think that Greg’s essay about evo-psych above is reasonable. Much more reasonable than the hatchet job in Pharyngula. It would appear that Myers has a rather imperfect grasp on variation and natural selection, though probably he just rushed his blog entry more than he would have a serious paper. Much better to read the Stanford Ency, of Phil. entry on the subject:

    All scientific disciplines suffer from bad papers. If we were to judge Physics by the worst papers on cosmology or by papers on “Heat” before Maxwell, it would look like a rather sorry enterprise. Someone (I.I. Rabi?) proposed that mediocre scientists be paid *not* to publish.


  11. I have an interesting spin on this. What would anyone say to someone having an advantage in a modern “social niche”, if they have a syndrome that confers advantages as well as drawbacks?

    I’m curious because I am in the process of using historical role-models to adapt myself to a better niche, given my psychology which has been shaped by evolution. A functional use of evolutionary psychology as it were.

  12. I like this post, but it is sort of oblivious of the wider context within which evolutionary psychology became so politicized.

    And that context simply is that for several decades an absolutist nurturist philosophy held sway in psychology and related social sciences, and political philosophy and other humanities disciplines like critical theory. That bias, similarly, had arisen to primacy against the earlier absolutist naturist philosophy. In other words, this is part of the long nature/nurture war as it exists within the interplay of science of political ideology.

    But at the height of this nurturist ascendency in the late 80s, or so, there began a golden era of new biological science about human cognition and behavior, which collectively began to erode the nurturist position.

    Which, given what you’ve written, I think you’ll agree that this erosion of an absolutist nurturist position is a good thing, inherently in accordance with all the rest of biology.

    However, the problem is that, to repeat, this is also deeply a contest of political ideologies. A great many folk who have an underlying political philosophy which finds a strong naturist position with regard to human cognition and behavior felicitous (generally cultural conservatives who like to argue that existing sociopolitical structures are inevitable consequences of inherent group differences — that is, the racists and the sexists and the like) have eagerly embraced EP and related as providing intellectual credibility. This is partly the case with some researchers, but it’s especially the case with science reporting and how this research is presented in the wider culture.

    In response, then, those who oppose the political reactionaries, particularly the anti-sexists and anti-racists, are put into a defensive position where they naturally oppose naturist work like EP and, over time, in the context of activist affiliations and such, EP and all similar research is dismissed out-of-hand and inherently reactionary and, interestingly, where maybe fifteen years ago there was dissent about a strong nurturist position (and, indeed, in the late 80s and early 90s, there was a stream of academic feminism which was very strongly naturist), today there’s a retrenchment into a very strong nurturist position, something close to an absolutism.

    It’s important to understand that very little of this highly-charged debate occurs within the context of much understanding or knowledge of any of the science involved. This is a proxy war about politics. Arguing that it’s absurd that it could be otherwise that human cognition and behavior is some complex combination of nature and nurture, and that it’s absurd to argue that simple causal explanations for cultural structures and such based upon biology are facile and suspect, or the opposite, are all unwelcome to most of the partisans in this argument. Admission of complexity and ambiguity about these issues is, to the partisans, a concession, an admission of weakness which the opposition will exploit (and they’re right, it will).

    Finally, the other, related context very specific to the development of EP is its criticism of the paradigm of human cognition as some sort of general purpose computer. This is related to both the blank slate nurturist philosophy and to the rise of computing theory and AI in the middle of the twentieth century.

    To my mind, this argument is very comparable to the arguments about “relativism” in the 90s. If you actually looked at what the academics who were writing about cultural and philosophical relativism through that period, it was nuanced and interesting. But in the popular imagination, “relativism” was a caricature of itself — it supposedly was the claim that there was no truth in any sense whatsoever, no right or wrong in any sense whatsoever. This wasn’t the case, but people believed it then and they believe this now. Because the popular arguments about relativism (moral or philosophical or cultural) are really arguments of political ideology given a facade of credibility of an authoritative scholarship. Just so with popular arguments about EP.

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