Monday, March 12, 2018

Is evolutionary psychology a deeply flawed enterprise?

We were discussing the field of evolutionary psychology at our local cafe scientific meeting last week. The discussion was prompted by watching a video of Steven Pinker in conversation with Stephen Fry. I pointed out that the field of evolutionary psychology is a mess and many scientists and philosophers think it is fundamentally flawed. The purpose of this post is to provide links to back up my claim.

There are several good sources of information that can be consulted. The Wikipedia articles note the controversial nature of evolutionary psychology [Evolutionary Psychology] [Criticism of evolutionary psychology]. The article by Stephen M. Downes on the Stanford Encyclopedia of Philosophy site is very comprehensive. It include an extensive discussion of the potential flaws in evolutionary psychology [Evolutionary Psychology]. Downes says ....
I said in my introduction that there is a broad consensus among philosophers of science that evolutionary psychology is a deeply flawed enterprise and some philosophers of biology continue to remind us of this sentiment (see e.g. Dupre 2012). However the relevant consensus is not complete, there are some proponents of evolutionary psychology among philosophers of science.
I think there's a broad consensus among evolutionary biologists as well. The critique from biologists is summarized by Robert C. Richardson (a philosopher) in his book Evolutionary Psychology as Maladapted Psychology.
The claims of evolutionary psychology may pass muster as psychology; but what are their evolutionary credentials? Richardson considers three ways adaptive hypotheses can be evaluated, using examples from the biological literature to illustrate what sorts of evidence and methodology would be necessary to establish specific evolutionary and adaptive explanations of human psychological traits. He shows that existing explanations within evolutionary psychology fall woefully short of accepted biological standards. The theories offered by evolutionary psychologists may identify traits that are, or were, beneficial to humans. But gauged by biological standards, there is inadequate evidence: evolutionary psychologists are largely silent on the evolutionary evidence relevant to assessing their claims, including such matters as variation in ancestral populations, heritability, and the advantage offered to our ancestors. As evolutionary claims they are unsubstantiated. Evolutionary psychology, Richardson concludes, may offer a program of research, but it lacks the kind of evidence that is generally expected within evolutionary biology. It is speculation rather than sound science—and we should treat its claims with skepticism.
You may disagree with these criticisms of evolutionary psychology but there's no denying that the discipline is being attacked. In fact, it's hard to think of any other academic discipline whose fundamental validity is being questioned so openly [Evolutionary Psychology Deserves Criticism] [How Valid Is Evolutionary Psychology? ] [Four Fallacies of Pop Evolutionary Psychology] [A Critique of Evolutionary Psychology] [A critique of evolutionary psychology].

The field of evolutionary psychology is full of hyper-adaptationist thinking. It's primary task is explaining modern features of human behavior as adaptations that took place in primitive human populations. From an evolutionary perspective, this requires that the behavior has strong enough genetic components to be subject to evolution by natural selection. It requires that primitive populations contained alleles for the modern behavior as well as alleles for a different behavior that reduced fitness. Finally, it requires that selection for the modern behavior is strong enough to lead to fixation in just a few hundred thousand years.

All of these assumptions require supporting evidence that is almost always missing in evolutionary psychology publications. In the absence of evidence, the default assumption should be that the behavior is cultural. If there's evidence of a genetic component then the default assumption should be fixation by drift unless there's evidence of selection [see 5 Ways to Make Progress in Evolutionary Psychology: Smash, Not Match, Stereotypes].

John Wilkins, among others, has attempted to defend evolutionary from these criticisms [Eww, I stepped in some evolutionary psychology and other crap] [Evopsychopathy 1. Conditions for sociobiology]. Steven Pinker has also responded to his critics [A defense of evolutionary psychology (mostly by Steve Pinker)].

In theory, it should be possible to mount an effective defense of evolutionary psychology by simply asking proponents to list the outstanding achievements of the discipline. One could then weigh the successes against the failures and reach a conclusion about the value of the field as a whole. PZ Myers tried to find some good examples of evolutionary psychology papers but he gave up [Kate Clancy tackles Evolutionary Psychology]. Jerry Coyne offered one paper as evidence that the field isn't entirely worthless [The Best of Evolutionary Psychology According to Jerry Coyne].

A few years ago I was discussing this issue with Gad Saad, an evolutionary psychologist at McGill University in Montreal, Canada. He defended his field by listing a number of notable achievements [The Great, Profound, and Valuable Works of Evolutionary Psychology]. I'll end this post by giving you his list and letting you decide for yourselves whether the field is worthwhile. As you read the list, ask yourselves the following questions ...
  • Is there evidence for genes (alleles) that are responsible for this trait?
  • Is there evidence that in primitive societies this trait improved fitness more than the original, presumably deleterious, trait?
  • Is there evidence that this is a universal trait present in all human populations?
  1. Women alter their preferences for the facial features of men as a function of where they are in their menstrual cycles. When maximally fertile, they prefer men possessing markers of high testosterone.
  2. Babies display an immediate instinctual preference for symmetric faces (at an age that precedes the capacity for socialization).
  3. Children who suffer from congenital adrenal hyperplasia display a reversal in their toy preferences. Furthermore, using inter-species comparisons, vervet monkeys display the same sex-specific patterns of play/toy preferences as human infants. This suggests that contrary to the argument made by social constructivists, play has an evolved biological basis.
  4. Individuals who score high on an empathy scale are more likely to succumb to the contagion effects of yawning. This is indicative that this particular contagion might be linked to mimicry and/or Theory of Mind.
  5. How provocatively a woman dresses is highly correlated to her menstrual cycle (a form of sexual signaling found across countless Mammalian species).
  6. Culinary traditions are adaptations to local niches. For example, the extent to which a culture utilizes meat versus vegetables, spices, or salt is a cultural adaptation (this is what behavioral ecologists study).
  7. Maternal grandmothers and paternal grandfathers invest the most and the least respectively in their grandchildren. Whereas all four grandparents have a genetic relatedness coefficient of 0.25 with their grandchildren, they do not all carry the same level of "parental uncertainty." In the case of maternal grandmothers, there is no uncertainty whereas in the case of the paternal grandfather, there are two sources of uncertainty. This last fact drives the differential pattern of investment in the grandchildren.
  8. Good male dancers are symmetric (paper published in Nature). One would expect that some behavioral traits might correlate with phenotypic quality as honest signals of an individual's desirability on the mating market.
  9. Self-preference for perfumes is linked to one's immunogenetic profile (Major Histocompatibility Complex).
  10. When a baby is born, most family members (especially those of the mother) are likely to state that the baby looks like the father. This phenomenon is found in countless cultures despite the fact that it is objectively impossible to make such a claim of resemblance. The reason for this universally found cultural tradition lies in the need to assuage the fears of paternity uncertainty.
  11. Environmental stressors (e.g., father absence) and the onset of menarche (first menses) have been shown to be highly linked. In numerous species, the likelihood of a female becoming reproductively viable is affected by environmental contingencies.
  12. Women are less receptive to mandatory hospital DNA paternity testing (for obvious reasons). In other words, their willingness to adopt a new product/service is fully driven by an evolutionary-based calculus.
  13. Women can smell the most symmetric men. In other words, women have the capacity to identify men who possess the best phenotypic quality simply via their nose. This is what I have referred to as sensorial convergence.
  14. Using fMRI, the exposure to ecologically-relevant stimuli (e.g., beautiful faces) yields distinct neural activation patterns in men and women.
  15. In choosing a mate, humans tend to prefer the smell of others that are maximally dissimilar to them along the MHC. This ensures that offspring possess a greater "defensive coverage" in terms of their immunological system.


  1. Re #15 -- that's the ridiculous "smelly T-shirt" experiment -- they measured supposed "mate choice" by having members of the opposite sex rate the attractiveness of people wearing a T-shirt that they hadn't changed! Saad thinks that was a notable achievement, I'd hate to see what he considered non-notable.

  2. Is evolutionary psychology deeply flawed? In principle no, in practice yes. There's no reason to think evolution can't, at least in principle, be brought to bear to inform questions relating to human psychology. Though I would certainly agree the work being done is anything but impressive or all that insightful.

    Your two latter questions seem rather strangely adaptationist to me however. Could historical evolutionary events not have shaped aspects of human psychology without them being selectively beneficial? It's almost like you ask the questions insinuating that insofar as no evidence of positive selection on certain psychology-affecting genes can be found, then no evolutionary explanation for that psychology even exists.

    Well, certain behaviors could be spandrels, unavoidable byproducts of other things that are adaptive, or they could be straight up neutral, but nevertheless manifest as they do because those neutral alleles still got fixed over geological time.

  3. "The field of evolutionary psychology is full of hyper-adaptationist thinking."

    It's not. EP from the outset went far beyond hyper-adaptionism. If There was a scale of how adaptionist somebody was and you had - say - Gould as a 2, Dawkins as an 8 and C.G. Williams as a 9, then "Evolutionary Psychology: A Primer" by Cosimides and Tooby, which served as the template for the discipline would rate as roughly 20 billion.
    The thing even the most hardcore adaptionist biologists always accept, is that it makes no sense to look at traits without undestanding their primitive states. Phylogeny matters to adaptionist thinking, because only by looking at the plesiomorphy can you compare the apomorphy and argue which advantage it confers. But to EP that is not part of what they call adaptionism. Their adaptionism is contrasted to the "phylogenetic approach", which considers common descent and thus plesiomorphic traits. It's incaple even of telling just so stories on how the ancestors of humans lost their tails, because it is incapble of considering that we had tailed ancestors. It won't tell you a just-so story on how we went from no opposable thumb, to an opposable thumb, because it considers the fact that we had ancestors without an opposable thumb to be irrelevant to any questions regarding modern thumbs.

    "Individuals who score high on an empathy scale are more likely to succumb to the contagion effects of yawning."

    I want to do that test. I'm severely affected by the contagion effect of yawning, to the point where somebody mentioning yawning makes me yawn (I've yawned 8 times while writing this paragraph). It's a great source of amusement for friends and colleagues, because to me that's a reflex. I've started to learn Japanese, and while it's of course hard to learn a new language, I now reflexively yawn when somebody says "akubi". There's obviously some higher brain functions involved, if I translate that term and immediately respond by yawning. I'm also pretty sure this is a bug and not a feature.

    "This suggests that contrary to the argument made by social constructivists, play has an evolved biological basis."

    Points deduction for the incorrect use of social constructivism.

  4. The list is a joke right/ thats their best stuff?
    I have heard/read about evolutionary psychology's demise. Its great fodder for creationists in attacking presumptions about selection.
    So many conclusions and hypothesis are foolish.
    Indeed they so easily guess some trait was useful to a primitive human population but its traits very unlikely/impossible they would be selected for and stick to some mysterious gene.!
    Yet i say its only in a spectrum of the whole evolutionary problem with evidence.
    i think evolutionists realize evo psych is hurting them in credibility.
    Its one of the few fields of study, where ppeople get paid to do it, that is attacked in academic circles.
    It looks simplistic and foolish beyond usual claims of experts status.
    When I used to read Uncommon Descent one of the authors had great articles on foolish claims in evo psych.
    Yes it shows a bigger problem with evolutionary biology.
    You can make any claim about genes doing this or that without actual biological evidence but instead hijacking other subjects like geology, genetics, comparative anatomy, biogeography.
    So for a creationist attacking evo psych is just attacking the extreme of the curve.

  5. It shows a bigger problem with religion.
    You can make any claim about gods doing this or that without actual evidence.

  6. I think you’re being a bit unfair. Even if the field isn’t very rigorous (I agree that the list is not very convincing), that doesn’t mean that the underlying premise is flawed. One could equally argue that ‘cancer research’ is flawed, since a lot of the work is being done on cell lines, with increasingly few people bothering to make the distinction between cell lines and tumour tissue. Both fields are theoretically sound, but in practise, they fail to be enough introspective to ask the right questions of how the work ought to be done. In addition, one could argue that any work on the genetics of behaviour (in either man or animals), is evolutionary psychology done correctly; I fail to see why the field should be restricted to human psychology. (And that might be a reason for the adaptionism; it’s the inferiority complex rearing it’s head again.)

    1. Not at all. Work on cancer cell lines is basically the equivalent of working on model organisms in other fields of biology. Everybody understands that they are just models used for simplification and are such the right tool for initial studies. Everybody understands that results in cell lines may not predict the results in mice or humans, just like results in E. coli or Drosophila may not be applicable beyond these organisms.

    2. Yes, in ideal conditions. Everything is a model of something. But I think there’s a tendency in the literature to get a bit carried away with the implications; cancer biology is just a case-in-point: before you’ve established that the model is satisfactorily similar to what you’re trying to model, I’m not comfortable to say that the work says much about anything. And I’m not sure in vitro cell lines are very similar to in viva cancers. Neurodegeberation is a similar issue: when you model it in a mouse (say), and then ‘cure’ it, unless you’ve established that the disease mechanisms are similar, you haven’t really accomplished much at all. We’re very good at preventing proliferation of cell line-derived cancers, or induced neurodegeneration, but our understanding breaks down when we try to apply it more generally—presumably because our models failed to capture the essence of the disease that were really interested in understanding. Trust me, not all scientists/researchers are clear-sighted enough to realise the limits of their models. In the ideal world, they would, but that’s not the reality we live in (sadly).

  7. Evolutionary psychologists are at least trying to use evolutionary theory to understand human behavior. If you look at a lot of the other social sciences, they are still stuck in a pre-1859 timewarp. Some went beyond rejecting Darwin and even rejected the scientific method for decades - e.g. cultural anthropology and history. Compared to some of these other efforts, most evolutionary psychology seems positively enlightened.

    1. nobody is stuck in the pre 1859 timewarp. nor rejected the scientific method as they understand it. I think the method is slippery when in use.
      History shouldn't be using evolution. Its about human motives and actions and investigation is after the fact. Indeed origin subjects are , largely, history ones.
      Evo psych has too many crazy conclusions that has lost it credibility by those who pay attention.
      Its just lines of reasoning from very raw data.
      Yes i say its not greatly different from evolutionary biology in its great conclusions.

    2. The historical method is basically a form of the scientific method. I suspect that both of you know very little how history is done.

    3. The historical method is not a form of the scientific method.
      Otherwise why qualify it with the word bASICALLY. Such a word hides a lot.
      the whole point of science is to be accurate in investigation, including definition, as to demand confidence in its conclusions.
      History can not make such demands.
      motives/actions of men long gone is only figured out by the remaining evidence which means a ceiling is always placed on conclusions because the the evidence quality has a ceiling.
      You make my case that some subjects, claimed to be science based, have problems with actually being worthy of scientific methodology confidence.

  8. Evolutionary psychology itself is not flawed, but some theories in the field are.
    Can anyone deny the fact that parents who were more resolute in protecting their offspring passed more of their genetic material than those who didn't?
    Can anyone deny the fact that a male who fathered many females passed more of his genes than the one who stayed with a single female? (It is more complex but the concept is the same.)
    In most cases men need time to realize that they love a woman. Women on the other hand need even more time to realize that they fell out of love for a man. Women invest more in having a child than a men, and so they invest more in the relationship, therefore it is more difficult to walk away from it. There is an evolutionary connection there.

    Then cultural differences are circumstantial. People do not gather to a city square and agree about their culture. The culture is a result of climate, geography and historical events. The successful cultures survive, and those that did not adopt to circumstances disappear. Culture itself is an evolutionary phenomenon.

    It is another thing that some authors fail to make a scientific case.

  9. "Can anyone deny the fact that parents who were more resolute in protecting their offspring passed more of their genetic material than those who didn't?"
    I can, unless you're making a circular argument where resolutely protecting parents are defined as those who have more kids.

    "Can anyone deny the fact that a male who fathered many females passed more of his genes than the one who stayed with a single female? (It is more complex but the concept is the same.)"
    This contradicts your first point, this is about offspring generation not protection. So I guess you deny one of these two premises.

    "In most cases men need time to realize that they love a woman. Women on the other hand need even more time to realize that they fell out of love for a man."
    Citation needed, because my BS detector is going off.

    "Women invest more in having a child than a men, and so they invest more in the relationship, therefore it is more difficult to walk away from it."
    One premise and two conclusions. Neither conclusion follows from the premise.

    "There is an evolutionary connection there."
    Says you.

    "Then cultural differences are circumstantial. People do not gather to a city square and agree about their culture. The culture is a result of climate, geography and historical events. The successful cultures survive, and those that did not adopt to circumstances disappear. Culture itself is an evolutionary phenomenon."
    Oy vey. See the above issues, they apply here as well.

    1. I wrote a comment not an essay.
      My point is that if a few researchers are wrong it does not mean that the theory is wrong, just those researchers. Then I threw a few ideas what could be a good topic for research, much better than what was given in this article. To me it seems that the author cherry picked the most ridiculous among them and used those to trash the whole theory. Cherry picking arguments to prove the point is politicking, not science.
      Granted I did not construct my comment right, but this is not an essay.

      Just few more lines:
      Parents are protecting their offspring. It happened through evolution, as we see that less evolved species do not care about their offspring, but have many of them, while more evolved spices have fewer but nourish and protect them. Those who didn't, did not pass their genes. In fact among mammals there are two very simple compounds Oxytocin, and Vasopressin that play that role. No citation, this is not an essay.
      A male can be a carrying parent and still be able to father many females in a short period of time.

      About men and women and how they enter and leave relationships, I ran it by psychologists and they agreed that there is something there. Needs research, of course, but I have my daily job - and what I do there I must not publish. Most people are not in academia.

      Give it the benefit of the doubt and try to see if you can prove it. Just for giggles.

    2. "Give it the benefit of the doubt and try to see if you can prove it."
      That's not how science is supposed to work. But I know it doesn't matter because you wrote a comment not an essay, ergo you can express opinion as fact and no one is allowed to point out problems with that.

  10. I may have a graduate degree but I'm not a scientist and I my experience is that people of science tend to deploy their rigorous skepticism on scales that slide with more subtle motivations. Of course when human values are at stake, this is what we all do. The brilliant insights of Jonathan Haidt in THE RIGHTEOUS MIND conjures the image of a huge elephant presumably steered by a human rider. The rider is a metaphor for our conscious, rational thought -- the elephant is a metaphor for all the bio-chemical, subconscious and unconscious parts of our being. Per Haidt, each of us is both the elephant and the rider -- and the role of the rider tends to be one of rationalizing the choices of the elephant AFTER THE FACT.
    To me it would seem that our life's mission is to master the elephant, and while we may have some moments of success, we fall short again and again and again. Dr. Jordan Peterson conjures a different image, he suggests that each of us consciously resolves to eat right, work out at the gym, and get ahead in our assignments -- yet afterwards we find ourselves sitting in front of the TV in our underwear eating Cheetos. The similarly brilliant Dr. Peterson points out that homo sapiens have been here for about 0.2 million years, but the brain chemistry we have is remarkably similar to animals that have been around for 600 million years, namely, lobsters. The point being that humans are driven by factors way beyond our conscious choice -- and our becoming more attentive to this reality helps to better master our lives.
    Now when others claim that evolutionary psychology is of dubious merit, it sends me on a tangent (for which I apologize). My gut tells me that perhaps the critics are taking sides in the feminism vs James Damore debacle. When Damore correctly repeated findings regarding the tendencies of males and females, not only was he was demonized, a grand movement arose to label all those who concurred as "evolutionary psychologists" (or worse) and public criticism of the field increased. So if what is really going on here with this article is a movement to discredit scientists like Dr. Haidt and Dr. Peterson, then just come out and say it.

    1. i never heard of james Damore. Yes I can understand other motives interfering with conclusions/methodology in subjects in science.
      Yet if feminism etc can interfere so much in conclusions from a science then somebody/everybody is saying the science is not real science.
      So its possible or more so.
      Evo psych has heaps of crazy conclusions constantly presented to the public or academia
      i'm not doubting its most likely some identity movement , at this point in history, makes commands about truth and freedom of science with both losing.
      however forceful people always rule the world. Democracy , academic freedom, and science must fight and conquer such oppressions.
      Trouble in the past, trouble in the present. creationism makes these complaints for sure. .

  11. To clarify, is it that you think Evolutionary Psychology is flawed from the outset, as people like Richard Lewontin once claimed? Or is it that, like PZ Myers, you haven't seen examples of good research motived by evolutionary approaches in psychology?

    If it's the first, I think it would be good to know your reasons for thinking its a problem at the outset. You allude to the idea that E psych is 'hyper adaptationist'. Is that the main issue?

    If you just haven't seen examples of good evolutionary psychology then, I would like to know your preferred theoretical disposition in psychology. It might be the case that you don't find theories of social interaction that rely on evolutionary assumptions to be compelling... But what's your alternative? Because I find much of social psychology very unconvincing and they are sometimes grounded in theories that are even less well supported than the 'hyper adaptationism' you see in evolutionary theories.

    1. Economic explanations for human behavior make a lot more sense than genetic ones. Why do you think people in the American Rust Belt voted for Trump? Do they have a "Republican Gene" or do they simply naively believe that Trump will bring back the factories and coal mines their fathers worked at?

    2. (Replying to Michael Payton)

      I just haven't seen good examples of evolutionary psychology, and would like to see one. A few years ago, I went looking, and delibrately avoided social psychology, looking instead for examples of evolutionary theory being used to give insights into cognitive psychology, especially visual pyschology. My only 'theoretical dispostion' in psychology is that I reckon cognitive psychology is the most rigourous area within psychology.

      For example, there is a bunch of papers about fear of (photographs of) spiders and snakes. I failed to find a good paper. Can you help?