I puked on Evolutionary Psychology before it was cool to puke on Evolutionary Psychology

I rejected it because it’s panadaptationist nonsense, among other things. But I’m always happy to see more arguments for why it is garbage, such as this criticism from a philosopher.

Evolutionary psychologists’ thought is that, for at least some of our behaviors, they believe that we have—dare I use this term—hard-wired cognitive structures that are operating in all of us contemporary human beings the same way they did for our ancestors on the savannas. The idea is that, in the modern world, we have sort of modern skulls, but the wiring—the cognitive structure of the brain itself—is not being modified, because enough evolutionary time hasn’t passed. This goes for evolutionary functions like mate selection, parental care, predator avoidance—that our brains were pretty much in the same state as our ancestors’ brains. The sameness in how our brains work is on account of genetic selection for particular modules that are still functional in our environment today. [Editor’s note: These “modules” refer to the idea that the brain can be divided up into discrete structures with specific functions.]

The matching problem is really the core issue that evolutionary psychologists have to show that they can meet: that there is really a match between our modules and the modules of the prehistoric ancestors; that they’re working the same way then as now; and that these modules are working the same way because they are descended from the same functional lineage or causal lineage. But I don’t see any way that these charges can be answered.

True, that. But just watch — evolutionary psychologists will rapidly retreat from those core ideas of “environment of evolutionary adaptation” and “modules” to find safety in the uncontroversial idea that the brain evolved.

We still get buckets of baloney about evolution from people who should know better. Have you heard of the pugilism hypothesis? This is the idea that men’s beards evolved to absorb a punch to the jaw. You only have to think about it for a moment to realize that getting socked in the face was a small factor in human evolution — 10,000 years ago, I would have been more concerned about starvation, getting a disease, breaking an arm while hunting, or getting thwocked in the back of the head with a rock by a bad guy. That facial hair might have provided a slight cushion to facial injuries doesn’t seem like the kind of thing for which there was much selection pressure, and I could also sit here and imagine all kinds of drawbacks to furry faces.

But it’s been tested! Except no, it hasn’t.

Because facial hair is one of the most sexually dimorphic features of humans (Homo sapiens) and is often perceived as an indicator of masculinity and social dominance, human facial hair has been suggested to play a role in male contest competition. Some authors have proposed that the beard may function similar to the long hair of a lion’s mane, serving to protect vital areas like the throat and jaw from lethal attacks. This is consistent with the observation that the mandible, which is superficially covered by the beard, is one of the most commonly fractured facial bones in interpersonal violence. We hypothesized that beards protect the skin and bones of the face when human males fight by absorbing and dispersing the energy of a blunt impact. We tested this hypothesis by measuring impact force and energy absorbed by a fiber epoxy composite, which served as a bone analog, when it was covered with skin that had thick hair (referred to here as “furred”) versus skin with no hair (referred to here as “sheared” and “plucked”). We covered the epoxy composite with segments of skin dissected from domestic sheep (Ovis aries), and used a drop weight impact tester affixed with a load cell to collect force versus time data. Tissue samples were prepared in three conditions: furred (n = 20), plucked (n = 20), and sheared (n = 20). We found that fully furred samples were capable of absorbing more energy than plucked and sheared samples. For example, peak force was 16% greater and total energy absorbed was 37% greater in the furred compared to the plucked samples. These differences were due in part to a longer time frame of force delivery in the furred samples. These data support the hypothesis that human beards protect vulnerable regions of the facial skeleton from damaging strikes.

I would concede even before testing it that a layer of hair over the face would reduce the force of impacts to some degree. But that’s not testing an evolutionary hypothesis! You need to show that this ‘padding’ had a measurable effect on survival and reproductive success. They merely looked at one superficial phenomenon and decided that dissipating the force of a punch to the jaw allowed beardy guys to thrive, in a world without the Marquis of Queensbury rules. It seems his beard didn’t save Otzi from the arrow that killed him.

There are a few people — thankfully few — that go wacko over their single comprehensive explanation. Apparently, humans evolved to be boxers.

More broadly, the results of this study add to a growing body of evidence suggesting that specialization for male fighting has played a significant role in the evolution of the musculoskeletal system of humans. For example, the short limbs (Carrier 2007), plantigrade foot posture (Carrier and Cunningham 2017), and bipedal posture of our earliest hominins ancestors (Carrier 2011), and the force–velocity tuning (Carrier et al. 2011) and size (Carrier et al. 2015) of the muscles of the human leg may also be associated with improved fighting performance.

Ugh. Umbrella Hypothesis alert.


  1. bcwebb says

    My immediate reaction was does a lion’s mane really protect it from biting at the neck and jaw? This seems very unlikely, especially as lions kill by crushing strangulation primarily. So we have one fairy tale used as evidence for another fairy tale.
    I’m also waiting for the discussion how beards give an opponent something to grab hold of and wrench the neck with; I can make up stories too.

    I will admit that when I saw the term umbrella hypothesis, I started think about how important opposable thumbs are in holding an umbrella properly. Clearly, this hand structure was evolved to deal with the life and death problem of staying dry in a rainstorm.

  2. larpar says

    The “pugilism hypothesis”. It’s bull, but I’ll play along. If I punch a guy with a beard, there will be less impact on my knuckles, therefore, I can punch him more times before damaging my fist.
    I need about a million dollars so I can do a cumulative impact follow-up study.

  3. says

    If you ask me, the human male beard is more like a peacock’s tail than a lion’s mane. Purely ornamental, completely useless. “I eat more better food so I grow more face hair.” “That make me better mate than bare-face.”

    Thousands of years later, in the 21st century, hipsters. That’s what thousands of years of selection based on secondary sex characteristics gets you, fucking hipsters.

  4. The Evil Twin says

    Beards being a combat vulnerability due to being a grab point isn’t completely silly; there are old Greek texts talking about how fighters kept their beards trimmed for just that reason. But that’s not evolutionary psychology, it’s history.

  5. says

    Actually beards are a sufficient bother that most men shave them off or trim them very short. This is forbidden by certain religions but they aren’t notably more prone to fistfights than others.

    I think the adaptive function was to store soup for later consumption.

  6. KG says

    My beard hypothesis is the complete opposite, and makes just as much sense. A beard is actually a disadvantage in a fight – your opponent/enemy can grab hold of it and pull – which is very painful. So, clearly, it has evolved, like the peacock’s tail, by Zahavi’s “handicap principle” – it serves as “honest advertising” of the wearer’s strength: “I’m so hard I can wear a beard and still win fights!”.

  7. says

    I’m also waiting for the discussion how beards give an opponent something to grab hold of and wrench the neck with; I can make up stories too.

    My very first thought exactly. See also “why Viking helmets actually didn’t have horns”.
    Seriously, those dudes play too many video games where resources are just lying around and go to the biggest bully. Maybe they should spend some time in the real world where resources are the result of human cooperation.

  8. Rowan vet-tech says

    Let me see if I understand this… They used sheep skin, which is thicker than human skin, and sheep wool, which is far denser than a human beard along with having different structure, and extrapolated to humans from that? What fucking bullshit. Their science is bad, their conclusions are bad and they should feel bad.

  9. nomdeplume says

    So, if I have understood the hypothesis properly, lion-tailed macaques have evolved for boxing even more than humans?

    What silly science. They should hang their bearded heads in shame.

  10. Ridana says

    You thought it was a rational explanation of why we look and behave as we do today, but IT WAS ME! DIO!! (somebody had to do it)

    Some authors have proposed that the beard may function similar to the long hair of a lion’s mane

    Of course it would be lions. Such a function might also be similar to the long hair of a sloth. Funny that’s not the example they choose. If protection is the key, why aren’t they asking why human males don’t have fleshy face plates like those well-known pugilists and our closer relatives, male orangutans? Why don’t females usually have thick beards? Males aren’t the only ones subject to jaw-breaking male violence.

  11. says

    Maybe the bear evolved to be a repository for fragrant urine, using a romantic method observed in male goats. Since ev psych researchers seem to behave like male goats this may be a residual evolved-in behavior: it’s for scent-marking.

  12. John Morales says

    … is that a Jo-Jo’s reference?!

    What’s a Jo-Jo? Is it like a yoyo?

  13. says

    Jeez, I’m 63 goddamn years old and I know about Jo-Jo’s Bizarre Adventure. How old are you people?

    At least it’s clear I’m going to be the only pop culture expert when they lock me up in the nursing home.

  14. John Morales says

    Hey, it’s not like I hang around the younger set like you, PZ. Also, I live on the other side of the world.

    I did Google it, and it turned up several thingies, such as a singer and a restaurant chain.
    So I asked.

    (Thanks, anyway)

  15. William George says

    @John Morales #18

    Jo-Jo’s at its core is just another Japanese fight comic/ animation show like Dragonball Z. But it goes about it in such a weird and highly stylistic way that it stood out from the crowd of muscle men punching each other. As you can imagine, like all “weird Japan” things it became very popular on the internet.

    It’s not my cup of tea, but Jo-Jo’s is worth a looksee just to appreciate that a creator with a unique vision can arise in any medium no matter how boring and samey it is.

  16. komarov says

    Aha, the time has come for me to publish my ancillary theory: pronounced doublechins evolved so that the fingers of the clenched fist slide sideways as they naturally “lock” into the contours of the chin. This dissipates up to 312% of the impact energy into relatively harmless sideways motion or knuckle/skin friction, the heat of which, by the way, is absorbed by a beard making it even more useful. The calculator also showed something with an E and a minus in it, but I don’t like that notation so omitted it

    Wait, the original theory is rubbish? Awww, there go my Nobel and Ignobel prizes. I was finally going to explain scientifcially why you’re not supposed to hit people with a closed fist (It’s inefficient).

  17. says

    i submit that anyone who wants to claim “beards make you safer from punches to the face” actually needs to throw a punch at a face. when their broken hand bones heal enough to type the report, i would be interested to read their musing on why humans don’t have fur-covered digits.

  18. Rich Woods says

    @WMDKitty #24:

    This is why long-haired Iron Age warriors would braid their hair, sometimes incorporating copper or gold wire, to act as padding when wearing a helmet. It’s also why dwarfs in LOTR braided their beards. Trufact.

  19. daverytier says

    The most galling thing about that kind of “evolutionary (arm chair)psychology”, is not the adaptationist feel-good nonsense. It’s when they start using it to justify all sorts of bad behaviors and evil ideologies.

  20. daverytier says

    Re. fistfights exerting significant selection pressure – then why are our knuckles so fragile and unprotected ? I mean if you punch out so many people so hard that it leaves a dent on the gene pool, there is a fair chance you cripple your hands as well.

  21. a_ray_in_dilbert_space says

    There are so many problems with Evo Psych that it is hard to know where to begin. However, I’d start with these three issues:
    1) It is not so much either evolutionary biology or psychology as it is a bunch of Just-So stories to explain the status quo without consideration of the abilities of humans or societies to change.
    2) It is usually used as an apologetics for the worst aspects of our society–racism, misogyny, inequality…
    3) It is anti-scientific–looking for evidence that supports a theory rather than evidence that might contradict it.

  22. says

    I’d always just thought face and body hair were affected by hormones, so the evolution of hormonal systems would have “side effects” on hair growth.

  23. Ridana says

    20) @William George:
    While JoJo began as a somewhat typical, if ludicrously dramatic, testosterone-fueled, fights manga, it’s always had good stories to tell that weren’t just about fighting or getting stronger. And with the 2nd season’s introduction of the concept of Stands (which was pure genius), I think it pretty much left the “muscle men punching each other” format behind, which Dragon Ball just doubled down on with its endless series of tournaments. After the first season though, 80-90% of the time the heroes win by outwitting their enemies rather than just out-punching them. The more bizarre the Stands get, the more strategy is involved.

    Stands are manifestations of the individual user’s fighting spirit and psyche, I guess, and their forms and crazy powers reflect their users. Stand users can be muscle men, old babas, teenage girls, babies, even animals.

    Some Stands are intelligent, some are not. One is a crew of sentient bullets who ride other normal bullets like Major Kong in Dr. Strangelove, guiding them and whooping it up like little kids playing cowboys. One is a motion-detecting blob of flesh that attacks and absorbs anything that moves. One is a tiny prop plane with gun mounts. Most would take paragraphs to explain all the intricacies and parameters of their powers.

    Stands only seem to be limited by Hirohiko Araki’s imagination, and he has proven endlessly creative over the last 30+ years in coming up with powers, ways to use those powers, and how to defeat those powers. Really, only a handful of the dozens of Stands or their users ever punch anyone. But when they do, it’s with fabulous style and much posing. :) I recommend it, but it’s definitely not for everyone (it can get pretty gruesome, with some really dark humor). Fun Fact: there are actually classes you can take to learn how to do all the JoJo poses. They are not easy. :D

  24. Owlmirror says

    @#32: That [“Is Evolutionary Psychology Possible?”] . . .. is the same paper linked to from the Gizmodo post cited in the OP, and which PZ has already blogged about twice, as noted @#19.

  25. blf says

    The mildly deranged penguin says female beards are an attempt to mimic her obviously superior natural tuxedo, and male beards are a poor imitation of that mimicry. She’s also quite pleased with evolutionary psychology, whilst still early years, it’s on-track to became another viral joke, maybe eventually rivaling teh abrahamic cults — they’re already developing a nonsensical rationale for war and murder, she notes. Her advice is to get the lions ready, whilst that doesn’t always work, their manes need to be kept sniny.

  26. says

    More broadly, the results of this study add to a growing body of evidence suggesting that specialization for male fighting has played a significant role in the evolution of the musculoskeletal system of humans.

    A problem with this quote is pretty obvious. We have no idea how much our ancient male ancestors actually fought with each other. But I wouldn’t be surprised if these guys think part of being a “real man” is being ready to fight at the drop of a hat.

  27. Owlmirror says

    More broadly, the results of this study add to a growing body of evidence suggesting that specialization for male fighting has played a significant role in the evolution of the musculoskeletal system of humans.

    A problem with this quote is pretty obvious. We have no idea how much our ancient male ancestors actually fought with each other. But I wouldn’t be surprised if these guys think part of being a “real man” is being ready to fight at the drop of a hat.

    Actually, that reminds me: the strongest male human is far weaker than the females of our closest non-human hominid relatives. This would tend to argue against the hypothesis that intraspecific combat was particularly important to human musculoskeletal evolution.

    I am also reminded of another hypothesis, the persistence hunting/endurance running model of human evolution, which offers explanations for multiple differences between humans and other hominid apes, most significantly those relating to the feet, legs, knees, hips, and buttocks/gluteus maximus. Cooperating with other members of one’s band/tribe to run down prey, in this model, was far more important, and of greater evolutionary impact, than any putative pugilism.

  28. johnthedrunkard says

    We ‘evolved’ to box? Then why are our hands too fragile to do it? Only after the invention of the boxing glove did blows to the jaw become practical. The only fracture I’ve ever experienced came from striking another teenage idiot in the head.

    The string of unsupported assumptions and a priori pseudo-facts is breathtaking:
    … often perceived …has been suggested … Some authors have proposed that.. This is consistent with the observation that …We hypothesized that…

    Did they even try to establish that the mandible actually IS ‘one of the most commonly fractured facial bones in interpersonal violence.’? I’ve read forensic studies of ancient battle dead, but NEVER anything about such jaw fractures.

  29. cartomancer says

    I despise this Jojo’s Adventure business. Not for anything it might be (though it really doesn’t appeal), but because I’ve had to sit through literally days of tedious conversations about it between my brother and his friends after they discovered it at university in Japan. To me it is the epitome of the niche interest that someone bangs on about all the fucking time, paying absolutely no attention to how bored you appear to be when they do.

    So tedious do I find it that I feel a strong urge to deliver punches to the face of the warbler, however well-padded by filthy keratinous excretions said individual’s face happens to be.

  30. John Morales says

    The beard thingy is adaptationist, but physiological rather than psychological.

    So, not a good example.

  31. unclefrogy says

    if fighting was so important that it influenced our evolution beards or not why are humans not much bigger and more powerful then our closest biological relatives the chimps while we may be on average taller we are certainly not stronger?
    uncle frogy

  32. says

    As any bearded father can attest, it is clearly an adaptation for child rearing. Not only is it a convenient handhold, it also gives pre-verbal infants an extremely effective way of painfully communicating their distress.

    When I picture our savannah ancestors, I can clearly see the men of the tribe stalking a gazelle with 2-3 healthy infants dangling from their full, paternal beards.

  33. tussock plant says

    I can’t help but notice the hair growth on my own body post-puberty arose on the parts of the body that are most distinct between childhood and adulthood. Such as the legs, lower arms, shoulders, lower back, ass, genital area, and of course the jawline.

    Did I get a hairy ass so people could slap it? That seems ludicrous, right? Probably because it’s different to the ass of a child and needed a hormone dose in puberty to set that into effect, and the hair, is just something else that same set of hormones happens to do. Like it does on the jaw.

    I mean, come on. It’s not complex of a problem, surely.

  34. militantagnostic says

    A hand holding a club, sharp object or even a short section of broom handle (pocket stick*) is far more effective striking weapn than a fist. Quirck and Quarks had a segment on the fist fighting hypothesis. In the comments numerous martial arts people pointed out that making a well butressed fist is not instinctive, it is something you have to learn.

    *I have been on the wrong end of a demonstartion of how to use a pocket stick.

  35. Jado says

    Actually, beards and moustaches evolved to allow easier and more covert ventriloquism. By throwing your voice and making insults come out of your rivals mouth, you had a greater chance of surviving longer than your opponent (who then had to deal with angry mobs and large people with sticks and rocks) and therefore progenitoring your genes (it is so a word.).

    But you never hear anyone debating this simple fact, do you? That’s because Big Academia is scared of the Ventriloquists!! If it becomes known that ventriloquists are the best, most successful progenitors, there will be no more women for all you “single-voiced” sad examples of masculinity (or non-masculinity, as is more likely the case). Just accept it – it’s understandable as being self-evident. But I wouldn’t turn up my nose a few million in funding to do some research. Just saying.

    And, hey, that guy over there is saying the same exact thing! Hell, he even sounds like me…

  36. René says

    The most heavily bearded hominid (and handsomely so!) is Pongo (look up “Bornean, Sumatran & Tapanuli orangs (horizontal).jpg”). They’re also the most solitary of Apes.

    So, there flies any pugilistics over our heads.