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It must be “Let’s all beat up Evo Psych” Day!

Earlier, when I was writing up that criticism of Rybicki and Stangroom, I read through that article on shopping and foraging and evolution that he had cited in defense of his views. There was something in it that drove me to distraction and made me want to find a match and light the whole paper on fire (a bit of indulgent exorcism of annoying work that is getting increasingly difficult to do; I was reading it on my iPad). It’s something that afflicts almost all of the evo-psych work on the evolution of sex differences, and it rankles. So let me try to purge my irritation in a way other than incinerating an expensive bit of electronics. Let me instead pretend to be an evolutionary psychologist.

First, let me stipulate that everything is a product of selection; that the only interesting features in human evolution are adaptive ones. This one really, really hurts, because I’m by no means a panadaptationist, and think a lot of features are far easier to explain as a product of pure chance rather than having to come up with an elaborate just-so story to rationalize them. But have no fear, I’ll return to a pluralist view at the end.

Second, the paper included this nice chart on the differences in roles in hunter-gatherer societies (it’s relevance to a paper on shopping preferences in 19 year old American college students is still in question).

I will stipulate that every single cell in that table is true. I’ll go further and stipulate that the correlation with the sexes is absolute and perfect: in all hunter-gatherer societies, women never hunt and use those hunting skills, and men never gather and use those gathering skills. I’m not an anthropologist, so that table could be totally crackers and there could be a thousand exceptions, but I’m not going to worry about it; we’re stacking the odds to favor the evo-psych hypotheses as much as possible right now.

Further, I will stipulate that many of those skills are biologically based and founded on genetically determined cognitive abilities, and that they have no overlap. That is, for instance, hunters need a theory of mind that is built on an elaborate cortical substrate in order to more efficiently predict the behavior of prey; this ability is not used by gatherers when they’re searching for tubers. Gatherers, on the other hand, need very precise sensitivities to color and nuances of shape to assist in pattern-matching while searching, abilities that hunters do not use.

I will also stipulate that these specific cognitive and perceptual abilities have no utility outside hunting or gathering. There are no social circumstances, for instance, in which these abilities might be an exaptation.

Finally, I stipulate that the circumstances that produce these adaptations are still relevant today, and that 95,000 years of human evolution in hunter-gatherer societies completely dominates and makes irrelevant the last 5,000 years of evolution in agricultural and urban societies; we can ignore any processes that might have undone prior adaptations.

Is that enough yet? Have I given enough of the store away? ‘Cause I’m really feeling a little psychic stress here, since giving up some of those premises makes me want to claw them back and stab them a few times, until they’re bleeding and dead. But I’m playing the game, let’s give evo-psych every possible advantage, and grant them every assumption they make as a default.

Now here’s the part that infuriates me when reading these sex difference papers. They almost always act as if they’re discussing two independent breeding populations facing different selection pressures.

But…

Every hunting man had a gatherer mother; every gathering woman had a hunting father.

Seriously, it’s this feeling that I have to remind them that they’re not dealing with two species, Man and Woman, or even two populations, the man-tribe and the woman-tribe, but one goddamned species, obligately breeding within themselves. If there is a ‘spatial navigating gene’, both men and women have it. If there is a gene that grants us the color sensitivity to distinguish puce from plum, we all carry it. With the exception of a minuscule number of genes involved in sex-specific trait determination on the Y chromosome, we’re sharing everything.

Wait, the naive among you are wondering, does that mean men are carrying genes for large breasts, wide hips, and ovaries, while women are carrying genes for baldness, baggy scrotums, and testicles? Yes, we are. All shared. But these genes are also regulated so that they are expressed or repressed differently in the different sexes. You have to think of each one as a Gene Plus: a gene plus an added switch to turn it on or off differently in different sexes (commonly, they’re regulated differently by the presence or absence of testosterone.)

In most of these reproductively relevant sex differences, it’s easy to understand what maintains the Plus; a man whose testes did not see the signal to make male-specific gonads and instead produced some very confused ovaries would be a reproductive failure. Some of the secondary characteristics are only weakly maintained — breast size, for instance, doesn’t seem to be a major factor in reproductive success, and we see a large variation in that parameter…but there are stronger pressures that have maintained lactation, and so that function is more reliable (but not invariant!)

This is the problem for the evolutionary psychology of sex differences: for each trait that you want to claim is a product of selection for a behavior that is different between sexes, you have to postulate a Plus that restricts its expression to a single sex.

You can’t simply have a just-so story that Woman evolved ability X to cope with gathering berries; you have to also have a just-so story that explains why Man evolved a repressor to shut off X for better hunting. And vice-versa for ability Y that aids in hunting.

So, sure, tell me that humans evolved cognitive mechanisms to aid in navigating by landmarks for better fruit and tuber searching, and I might well believe it to be reasonable; now tell me why you think it would only operate in women, and how it would be actively suppressed by genetic mechanisms in men. Then you can tell me why navigating by distance and direction is actively shut off in women. You’re the ones who like purely adaptive explanations: why would there be an advantage to individuals having each only half the suite of potential genetic navigation tools switched on?

And then you can go through each line in the table up above and explain how confining each of those abilities to only one sex or another led to more babies being made than if both had it, and how having that trait in an ‘inappropriate’ sex would be culled by death or reduced fertility…because you know that’s how evolution works, right?

Right about then, my inner pluralist will come roaring back to life, and I’ll have to point out that your feeble rationalizations, even if I were to accept them, can only represent tiny fitness effects, and that in small populations of humans drift is going to dominate over small fitness coefficients, and selection won’t even see your hypothetical advantages. And maybe you don’t understand how evolution works, after all.

I think a better answer is that there are evolved human traits that are shared among every individual in the population without regard to sex, and that culture acts as the repressor/enabler of particular attributes in particular individuals. That ought to be the default assumption, with exceptions requiring exceptional evidence beyond just reading the cultural codes. Change the culture, and all those fully human abilities can be expressed in everyone, not just the ones permitted by convention.

Anything else is a betrayal of our potential.

Comments

  1. Pierce R. Butler says

    I will stipulate that every single cell in that table is true.

    We’ll have to take your word for it: every single cell there is unreadable.

  2. Maureen Brian says

    Please stop banging your head against these idiots, PZ. You’ll do yourself an injury. Just ask them …

    How would you raise a human from neonate to stroppy adolescent without a theory of mind?

    And how did we develop language if all the important people eschew conversation?

  3. says

    I like banging my head against idiots. It’s like popping bubble-wrap — it’s so satisfying to see the thin little shells enclosing naught but air collapse.

  4. chigau (無) says

    Take a spherical hunter and a spherical gatherer…
    (whoever made the table learned about gatherer-hunter societies from Alley Oop and the Flintstones)

  5. says

    Yeah…I seem to recall that one evo-psych hypothesis was that language initially evolved for communication during hunting.

    But of course, they’re all ad hoc hypotheses, aren’t they?

  6. billseymour says

    Hmm…

    OK, when I shop for clothes, I know what I want, find it, buy it, and leave. That fits the theory.

    But when I walk into a store that sells model trains…

  7. says

    Yeah…I seem to recall that one evo-psych hypothesis was that language initially evolved for communication during hunting.

    Yeah, language certainly wouldn’t have been necessary for any other tasks, especially all those sissy ones.

  8. cyberCMDR says

    Here’s a counterexample for the evo-psych crowd. I’m male, but my wife is much better at navigation than I am. (She’s much better at many other things too!). She has what we call a “map in her mind”, and if we go someplace once she can get us back there again.

    Regarding myself on the other hand, I routinely forget where different stores are, or where the correct turnoff from the highway should be. It may be an acquired dependency on my part since she is so good at it, much like my lack of competence in the kitchen. The fact is though that there are no absolutes regarding gender characteristics.

    I think at heart the evo-psych crowd is less interested in learning the truth than attempting to define “norms” that validate their own gender prejudices. This is much like the pseudo-science used in the South to justify treating slaves and their descendants as sub-human.

    “Man is not a rational animal, man is a rationalizing animal.”

  9. Brownian says

    Yeah…I seem to recall that one evo-psych hypothesis was that language initially evolved for communication during hunting.

    Thank god they moved on to Christmas shopping, because this paper directly contradicts that hypothesis:

    Gathering is much more conducive to socialization than is stalking game. Hadza hunters are usually solitary, but will form tracking parties if one hunter discovers particularly abundant game (Hawkes, 1996). Although men may use the necessity of hunting trips as an opportunity to socialize, once the actual hunting is underway it becomes much more of a silent, pragmatic activity. Keeping quiet is much less important when stalking vegetables. Thus gathering is more conducive to socialization, and gatherers could converse to pass the time during this routine activity. Moreover, women might still socialize when not foraging because in foraging cultures women tend to spend their days in the company of other women and children (Hawkes, 1996). In addition, gathering was a more frequent activity than hunting and consequently, the larger allocation of time to gathering provides more opportunity for socialization.

    I’m reminded of a lecture I once saw by a noted researcher. Some digging allowed me to find a transcript. Not only was his argument more logically supported, but it was much more entertaining as well:

    Men flip around the television more than women, I think. Men get that remote control in their hands, they don’t even know what the hell they’re watching. You know, we just keep going, “Rerun, don’t wanna watch it.. ” “What are you watching?” “I don’t care, I gotta keep going.” “Who was that?” “I don’t know what it was – doesn’t matter, it’s not your fault. It doesn’t matter, I gotta keep going.” Women don’t do this. See now, women will stop and go, “Well, let me see what the show is before I change the channel.” You see? Men just fly. Because women, you see, women nest and men hunt. That’s why we watch TV differently. Before there was flipping around, before there was television, kings and emperors and pharaohs and such had story-tellers that would tell them stories ’cause that was their entertainment. I always wonder, in that era, if they would get, like, thirty story-tellers together so they could still flip around. Just go, “Alright start telling me a story, what’s happening? I don’t want to hear anymore. Shut up. Go to the next guy. What are you talking about? Is there a girl in that story? ..No? Shut up. Go to the next guy. What do you got? I don’t want to hear that either. Shut up. No, go ahead, what are you talking about?.. I don’t want to hear that. No, the all of you, get out of here. I’m going to bed.”

    There’s some food for thought.

  10. Robert B. says

    It is inarguably true that the human brain has been shaped by the circumstances in which it evolved. I’m sure we will learn a great deal from this valuable insight, just as soon as some smart scientist learns how to make credible observations and/or experiments on the topic.

    *waits* Any day now…

  11. Michael says

    Another issue is that the “poor” or “unsuccessful” male hunters would have to stay home and help gather rather than hunt, which would invariably increase their reproductive success (while the competition was out hunting).

  12. says

    The concept of evolutionary psychology is valid. The problem with people like Rybicki, is that instead of promoting evolutionary psychology, they promote garbled nonsense that has nothing to do with evolution or psychology.

    Therefore, I propose that in this context, the phrase “evolutionary psychology” be replaced with “evolutionary Scientology”.

  13. chigau (無) says

    Michael #14
    I think that was recapitulated in High School with the few boys who took “Home Ec” class instead of “Shop”.
    ;)

  14. says

    The concept of evolutionary psychology is valid

    Depends on what you mean by “valid”. I think questions it raises can be valid but I have trouble finding out what specifically that field itself can do to answer the questions. It seems that those questions are more likely to be solved by anthropology, genetics, sociology and neuroscience; which means that evopsyche is what? An attempt to synthesize the other fields? Making up narratives from the research of the other fields?

  15. transenigma32 says

    Maybe it’s just me, and I have no desire to Google this because evopsych is already a bunch of transparent ad hoc garbage, but I’d love to see how they explain people who fall outside of the gender binary: men who identify as women, women who identify as men, women who become men, men who become women, people who are either, people who are both, people who are neither or anything else I’m forgetting. Every paper I’ve seen has been “male/female”, with no variation given for people outside of the “gender norm”. If you were truly interested in the role evolution played in our psychological development and the sex roles, then you’d definitely at least *mention* folks who don’t live in the traditional binary. But from what I’ve seen, they don’t. I’d love to see their take on the folks who defy the “male/female” binary check box.

    Wait. What the hell am I thinking? No I don’t. They can keep their dated ideas of the gender binary and pretend that they have science backing it up. I’d rather not hear their opinion on people like myself.

    /delurk

  16. says

    Yeah…I seem to recall that one evo-psych hypothesis was that language initially evolved for communication during hunting.

    Yeah, the amount of communication involved is really going to depend on what you’re hunting. If you’re going after an elephant or trying to run a whole herd of bison off of a cliff, there’s a lot of coordination involved, but if you’re stalking deer with a bow or antelope with a spear, more people is just more chance they’ll hear or smell you and spook, so nobody gets any. And if you’re going after small game like rabbits, you’re setting snares if you have any sense, which is also a pretty solitary activity as there’s no point in setting them too thickly. Gathering on the other hand, “Hey! I found a big patch of tubers over here! Everyone come and help me pick these!” or “Nothing over here, let’s move on.” The utility is obvious, beyond the simple social bonding functions, which are probably at least as important a factor developing language.

  17. opposablethumbs says

    Thank you; this post with its elegant pwnage is a thing of beauty. I had not appreciated just how comprehensively the purveyors of evo psych drivel shoot themselves in the foot.

  18. Menyambal --- in flagrante delicto says

    Most men have a couple of nipples on their oh-so-manly chests. Seems men are carrying some very female-specific physical features around. (Some men may not have found the place where women carry their very-much-male feature.) Ignoring the physical to assume that behaviors would cleanly split between sexes is just goofy.

    I’m male, and sometimes I see pictures of women that seem extra interesting in a certain way—then I realize that the pose/picture has two roundish areas and an arching upthrust, and looks like an erect penis. I dunno if that’s “gay” or not, but a lot of males are very happy to indulge in allegedly-female sexual behavior, so there has to be some serious overlap, and there cannot be a clean division between gender behaviors.

    As for language between hunting and gathering, I’d say that hunting could be carried out in dead silence, but gathering would require at least an ability to say, “Don’t eat that, it’s poison.”

    As for men and women having different habits in stores, you could say it depends on the store. Send a guy into a hardware store to buy a bag of nails, then observe his behavior. Or a sporting goods store, maybe. Or even the meat department when when grocery shopping, if you want to keep the sexism going.

  19. says

    Moreover, women might still socialize when not foraging because in foraging cultures women tend to spend their days in the company of other women and children (Hawkes, 1996). In addition, gathering was a more frequent activity than hunting and consequently, the larger allocation of time to gathering provides more opportunity for socialization.

    If the women are capable of socializing when not foraging and men spend less time hunting than women spend foraging, what the fuck are the men doing in all that spare time instead of socializing? Staring silently into the air?

  20. Sophia, Michelin-starred General of the First Mediterranean Iron Chef Batallion says

    Caerie:
    They were in their man-caves, sharpening spears using the latest StoneWare PowerSharpener tools, of course. And drinking rotten vegetable matter whilst grunting, farting and burping loudly.

    Because that’s EvoPsych.

  21. vaiyt says

    Every hunting man had a gatherer mother; every gathering woman had a hunting father.

    Beautiful. The entire castle of cards that comprises the arguments for the separate evolution of men’s and women’s abilities crumbles in one sentence.

  22. Azkyroth, Former Growing Toaster Oven says

    How would you raise a human from neonate to stroppy adolescent without a theory of mind?

    And how did we develop language if all the important people eschew conversation?

    So, wait, they’re positing that “theory of mind” developed only in men, when women are supposed to be the ones with native empathy and emotional intelligence?

    And that pattern recognition and spatial functioning developed in women, when “everyone knows” women suck at math?

    Can’t the sexist shits at least be consistent?

  23. strange gods before me ॐ says

    There is a wide variety of stuff that gets referred to as theory of mind. Some of the peripheral might be disposable. (?)

  24. strange gods before me ॐ says

    That comment was meant to refer to #3 not #28. I don’t want to believe that someone would say theory of mind developed in one gender.

  25. strange gods before me ॐ says

    Shit, though, is that what #3 is saying too? Odin help us. I’m a bit lost though.

  26. Azkyroth, Former Growing Toaster Oven says

    I think we’re all responding to

    That is, for instance, hunters need a theory of mind that is built on an elaborate cortical substrate in order to more efficiently predict the behavior of prey; this ability is not used by gatherers when they’re searching for tubers.

  27. mildlymagnificent says

    this ability is not used by gatherers when they’re searching for tubers.

    Of course, gatherers never once took any notice of other animals feeding on something that indicated ripeness or availability. Equally, they’d never have bothered to recognise the signals of birds protecting nests indicating that, just possibly, there might be nutritious, fresh, tasty eggs to be collected.

    Nuh, uh. Gatherers always did everything the hard way. They always ignored every signal in the world around them of the existence and location of the best food for the season. They just trudged on.

  28. says

    Oh dear
    Every single cell of that table is just plain stupid.
    So, the manly man hunterers didn’t navigate by landmarks. They talked about moving 2678 paces south-east. Nobody ever said “let’s go to the river valley where the deer come to drink at this time of day. And when they had killed the prey and walked home, nobody took heed of that fucking mountain over there at the foot of which the cave was. And they walked silently. Hunters and fisher bragging about their success must be some very new thing (could well be, but you can’t have it both ways).

  29. nms says

    And they walked silently. Hunters and fisher bragging about their success must be some very new thing

    Manly men bragging about their kills communicate mostly through mime.

  30. Tony ∞The Trolling Queer Duck∞ says

    @22:
    I’m sure the males back then did the same thing men today do when bored-spank the monkey (errr, perhaps I should say choke the chicken given your ‘nym)

  31. unclefrogy says

    I know of one area where language is the most important that would communication with children. Of all the animals I know about we are the one who relies on learning the most. We have learn just about everything from each other we use language extensively to teach our children our very complicated ways our culture our names and all the skills we need to survive long enough to reproduce. We do not have to relearn or rediscover already acquired skills and experiences.
    We are taught in our very long childhood.
    Sorry I took most of that post as a joke. Were they being serious?

    uncle frogy

  32. pacal says

    That table you gave is risible to the nth degree. For example the notion that men hunting rather than women gathering have a larger range is debatable and besides it depends on the environment and season. The navigation differences is also risible and nothing more than assumptions. Hunter-gathers use both generally. Even the stuff about larger kills are preferred varies from group to group. It also ignores that the great majority of kills among Hunter-Gathers are small game. What is generally preferred is what takes the least effort and time.

    As for return quickly after the kill. Again an assumption which ignores that meat tends to rot faster than vegetable matter. Oh and is this even really true in comparison to women returning from gathering? The sharing and not sharing difference is flatly wrong. The Social status thing is flatly wrong also. But the Socializing thing is hilarious. I guess they don’t have a clue about how !Kung Bushmen like to talk and chat and story tell for hours around a camp fire for hours at night. Or how about !Kung of both sexes socializing for days on end. Nope instead a repeat of the tired stereotype of talkative women and silent men. All of course ignoring the anthropological literature.

    The stuff about childcare can be dismissed as utter nonsense.

  33. Sili says

    There was something in it that drove me to distraction and made me want to find a match and light the whole paper on fire (a bit of indulgent exorcism of annoying work that is getting increasingly difficult to do; I was reading it on my iPad).

    There’s not an app for that?

    I see a market for a clever programmer.

    Just imagine hitting the “Set on Fire” button and watch the satisfying incineration on the screen, when reading/watching something annoying.

    Hell, it’d make it a sport to watch Bill O’Rly.

  34. says

    I get arguments of the No True Scotsman variety by the evo-psych defenders I know. “No serious evo-psycher…” Assuming such rare unicorns exist, one would think they’d be appalled at how their research is being used to justify gender discrimination at best, and some seriously stanky rape apologism at worst. One would think they’d be a little more outspoken in condemning the common popular presentation of their research – basically, article after article explaining shitty male behavior as “hard-wired”. One would think.

  35. says

    Wait, the naive among you are wondering, does that mean men are carrying genes for large breasts, wide hips, and ovaries, while women are carrying genes for baldness, baggy scrotums, and testicles? Yes, we are. All shared.

    Indeed. As a transsexual I am very glad for this too. I’m having the same rapid breast growth that my youngest sister had despite my annoying Y-chromosome.