It’s a bad time to be a gender essentialist/evo psych advocate

It takes a while to assemble a comprehensive rebuttal to pseudoscientific claims — everyone who has dealt seriously with creationists knows that, absurd and ignorant as their arguments are, it takes hard work and diligence to assemble a coherent, evidence-based criticism, something I wish a lot of people who think debating creationists is easy would realize. It’s the same story with that James Damore memo. It’s easy to see that it’s garbage, but much harder to assemble the details of a rebuttal.

Fortunately, the well-research criticisms are steadily emerging now. For instance, Caryl Rivers and Rosalind C. Barnett can declare that “We can say flatly that there is no evidence that women’s biology makes them incapable of performing at the highest levels in any STEM fields”, and back it up with citations.

Many reputable scientific authorities have weighed in on this question, including a major paper in the journal Science debunking the idea that the brains of males and females are so different that they should be educated in single-sex classrooms. The paper was written by eight prominent neuroscientists, headed by professor Diane Halpern of Claremont McKenna College, past president of the American Psychological Association. They argue that “There is no well-designed research showing that single-sex education improves students’ academic performance, but there is evidence that sex segregation increases gender stereotyping and legitimizes institutional sexism.”

They add, “Neuroscientists have found few sex differences in children’s brains beyond the larger volume of boys’ brains and the earlier completion of girls’ brain growth, neither of which is known to relate to learning.”

Several major books have debunked the idea of important brain differences between the sexes. Lise Eliot, associate professor in the Department of Neuroscience at the Chicago Medical School, did an exhaustive review of the scientific literature on human brains from birth to adolescence. She concluded, in her book “Pink Brain, Blue Brain,” that there is “surprisingly little solid evidence of sex differences in children’s brains.”

Rebecca Jordan-Young, a sociomedical scientist and professor at Barnard College, also rejects the notion that there are pink and blue brains, and that the differing organization of female and male brains is the key to behavior. In her book “Brain Storm: The Flaws in the Science of Sex Differences,” she says that this narrative misunderstands the complexities of biology and the dynamic nature of brain development.

And happily, the widely held belief that boys are naturally better than girls at math and science is unraveling among serious scientists. Evidence is mounting that girls are every bit as competent as boys in these areas. Psychology professor Janet Hyde of the University of Wisconsin–Madison has strong U.S. data showing no meaningful differences in math performance among more than seven million boys and girls in grades 2 through 12.

I also like this article by Erin Giglio, a Ph.D. student in evolutionary biology, who discusses the complexity of sexual development and evolution, something avoided by the reductionist generalizations of privileged dabblers like Damore (‘there are only two genders!’ is their rallying cry). But she also makes a significant criticism of the whole evolutionary psychology approach.

Curiously, however, these disciplines do not include evolutionary psychologists: I have never met an evolutionary psychology student taking any course, presenting at any evolutionary biology seminar, or interacting in any way with the evolutionary biology students in my own department, and I have never seen a behavior-focused Ecology, Evolution and Behavior student from my own department mention spending time learning from evolutionary psychologists. This is particularly odd because my university, which is the University of Texas at Austin, happens to host an extremely prominent evolutionary psychologist in the form of Dr. David Buss…and also several prominent and well respected behavioral ecologists in my department, most of whom are specifically prominent in the field of sexual selection and courtship behavior itself. This is also a topic that evolutionary psychologists have a well documented and particularly strong interest in, and this includes Dr. Buss. So why the lack of collaboration?

The answer boils down to the fact that evolutionary biologists and behavioral ecologists — which is, again, the term usually used to describe people studying the evolution of animal behavior in a naturalistic context — are typically some of the most vocal critics of evolutionary psychology. Indeed, several prominent behavioral ecologists have written popular science books that criticize evolutionary psychology openly.

Why might this be the case?

One huge issue is the question of adaptationist hypotheses. Evolutionary biology had a large intradisciplinary discussion back in the late 1970s and early 1980s about adaptationist thinking, largely kicked off by Stephen J. Gould and Richard Lewontin’s classic paper The Spandrels of San Marcos. The central argument of this paper is that evolutionary biologists should not assume that the null expectation for any observable biological trait is that the trait is in some way an adaptation for survival. Indeed, some traits arise as accidents of pleiotropy — genes with multiple effects — and some merely develop over time by chance. Gould and Lewontin argued that in order to describe a trait as a known evolutionary adaptation, evolutionary biologists first needed to identify some evidence that the trait was both adaptive to survival and also that it had sufficient heritability for selection to be capable of acting on it.

While this paper was controversial at the time it was published, it has largely become accepted among evolutionary biologists that it is generally correct. In fact, I have most often seen evolutionary biologists use the term ‘adaptationist thinking’ amongst themselves as a slur, implying that another scientist’s research paradigm is insufficiently critically rigorous; it’s a term right up there with ‘telling Just-So stories’ within the field. It doesn’t mean that you can’t hypothesize that a trait evolved because of positive selection — it just means that adaptationist hypotheses must be tested against a null, neutral hypothesis.

By contrast, evolutionary psychologists openly argue that adaptationist assumptions are essential to the field and are simply good science, and that starting with adaptationist hypotheses just makes sense. This is further confounded by the methodology generally chosen in the field of evolutionary psychology (see below), which is typically limited to surveys confirming that the behavior in question does in fact exist — something even acknowledged by defenders of the field’s capabilities of falsification. Occasionally fMRI studies are also used.

Yeah, I’ve seen this behavior myself — Evo psych people react to the name Gould like you’ve just summoned Satan. While guilty of some hyperbolic overreach, Gould’s views have largely been accepted: you can’t simply say a trait exists, and therefore it has an adaptive purpose. That completely undermines the Evo Psych ‘research program’.

If you’re one of those people who read Damore’s memo and thought it sounded reasonable, brace yourself. You’re like the buffoon who read about Flood geology and thought that sounded like a good alternative hypothesis, who is about to get crushed by the deluge of real scholars of geology and paleontology and biology who will be pointing out how stupid the argument is. The people who actually understand the fields Damore was abusing are rising up now.

Don’t panic too much, though. Just as the creationists keep churning out excuses and exercises in motivated reasoning to defend their nonsense, you’ll still have ranks of evolutionary psychologists shoveling crap to keep you happy.

Oh gob, evo psych again?

You may have already heard that Ed Clint, a guy who has been dedicated to bashing Skepchick and Freethoughtblogs for over a year, has cloaked his biases in a pretense of objectivity and written a long critique of one of Rebecca Watson’s talks, accusing her of being a science denialist and anti-science because she so thoroughly ridiculed pop evo psych. The excesses and devious misrepresentations in that post were painful to read, as was the revelation that Clint is throwing away his career by jumping on the evo psych bandwagon in graduate school (I frequently advise students on good disciplines to pursue in grad school; bioinformatics and genomics have a great future ahead of them, as does molecular genetics and development, but evolutionary psychology is one I would steer them well clear of, as a field that has not and will not ever contribute much of substance. The good papers in evo psych are the ones that use the tools of population genetics well and avoid the paleolithic mumbo-jumbo altogether).

Fortunately, Stephanie Zvan has already torn into his ‘analysis’, showing that it’s mostly misplaced and misleading. I’m relieved, because I’m going to be tied up for a while, and I found Clint’s response to be extremely irritating.

One think that particularly rankled is that Clint puts up a pretense of being objective and that his criticisms are nothing personal; bizarrely, he even puts up a photo of himself taken with Rebecca Watson as if that were evidence that he’s not biased against her. What he doesn’t mention is that he’s been sharpening an axe since the “elevatorgate” episode; together with a disgruntled ex-FtB blogger who left in a bizarre huff over not getting enough respect, he founded a competing network (which is fine, of course) which they proceeded to stock almost entirely with writers with an an anti-FtB and strongly anti-Skepchick slant — I’ve had to laugh at the lineup which looks largely drawn from the ranks of the Slymepit, a notorious anti-feminist/anti-Rebecca Watson hate site, and my list of banned commenters. And looking at the people who comment there, again, they seem to be largely driven by hatred of Watson and feminism in general.

Again, that’s fine — we have biases here at FtB, too, in that we tend to be pro-feminist and when we founded it, I specifically told Ed Brayton that we needed to be sure to include more than just old white guys like us — but what isn’t fine is to lie about your motives. Any day, I’ll prefer open antagonism from an avowed enemy than fair and dissembling words from an Iago.

For example, after telling people to avoid insults in the comments, this is what Clint has to say:

Although PZ’s behavior is unfortunate, I would urge a modicum of compassion. I believe he lashes out because he feels so small and vulnerable, and because he is. I can think of few other reasons for such unprovoked barking. He is making a mistake in coming after me. He will be wounded by it. I wish it didn’t have to be this way, and that we could just have a calm chat about it.

Condescending and smarmy, isn’t he? Ick. He won’t call me names, he’ll just call me “small and vulnerable.” Man, I despise that kind of sliminess.

I’ll follow up on Stephanie’s post later this week, when my schedule calms down, and what I intend to do is dig into the substantive flaws in both Clint’s hatchet job and in that awful discipline of evolutionary psychology. Seriously, in the reviews Clint recommended to give the background on what evo psych is, I was appalled — do these people have any understanding of modern evolutionary theory at all? I think the answer is clearly “no.”

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.

What do others think of Evolutionary Psychology?

Over there on Reddit, there is a subreddit called r/evolution for the discussion of evolutionary questions and issues. There is now consideration of a rule to clarify their stance on evolutionary psychology. It’s a good one.

As you know, the moderator team has been considering the possibility of new rules to help improve things around here. And of course, we wanted to get the community’s feedback on the matter before we pulled the trigger. Please, just remember to voice your disagreements peacefully.

  • Rule #X: Evolutionary Psychology. The moderation team takes the stance that evolutionary psychology is pseudoscience. Like any pseudoscience, it starts with a conclusion rather than drawing that conclusion from data; it also tends to ignore or even demonize other fields of science that already provide information about the topics it addresses; and tends to boil personal behaviors and preferences (as well as complicated sociocultural and developmental phenomena) down to a handful of terms it uses as buzzwords to craft adaptationist/bioessentialist just-so stories that are often untested, untestable, or even wildly incorrect. It’s also frequently used to justify everything from preexisting biases all the way to dehumanizing rhetoric. These posts also tend to attract a lot of baseless speculation and experts on these topics are often drowned out by negativity and downvotes, all of which is antithetical to the climate we’re trying to cultivate.
  • Please note that while we discourage evolutionary psychology and pseudoscience in general, simply asking questions about the evolutionary basis for certain human behaviors or cognitive traits isn’t necessarily an issue: there are legitimate scientists in various fields (eg, anthropology, especially evolutionary anthropology, ethnography, behavioral genetics, etc), who study these topics with proper, physical data, and so there is information out there. However, if we feel that a question is better suited for other academics (eg, regular psychologists, historians, sociologists, philosophers, etc), if things start getting pseudoscientific, or if certain lines are crossed, we may choose to intervene.

More pithily, they say the “problem is that evolutionary psychology is science in the same way that Taco Bell is authentic Mexican food.” There is some polite agreement with the statement (I’m not saying anything, because I’d only provide loud impolite agreement) and some polite disagreement. The disagreeable all seem to be quoting Tooby & Cosmides, which to me is just another sign that it’s a cult. EP has existed for decades, and all you’ve got to show for it is a pair of aging, founding authorities and a swarm of lunatics and bad publications? Cut your losses. Treat EP as crackpottery.

As far as I’m concerned, the statement is fair and judicious.

I f’in hate evolutionary psychology

Sorry, I saw this evo psych study and had to vent.

Here’s the protocol: subjects were primed with powerpoint slides of modern economic devastation with an explicit slide with text saying the 21st century is a “harsh and unpredictable world”. The controls, near as I can tell, saw the same slides without the text. Then they flashed a slide of topless women’s torsos with breasts of varying shapes and sizes, and asked the subjects to rate the women.

Let me just say that if you’re doing any kind of psych study that ends with a request to rate women’s breasts, you’re doing something wrong. I can’t even begin to unpack all the assumptions you’ve pre-loaded into the work.

And then the results are underwhelming: a bunch of bar graphs that show very little variation in the responses, with a few showing statistically significant but totally unimpressive differences. Overall, men rated women with larger breasts as more attractive, fertile, healthier, reproductively successful, and likely to befriend. The n was 144, all drawn from college students at a midwestern American university, so of course we can infer universal principles of human evolution from it.

Here’s the kind of graph you can make as an evo psych goofball.

Dazzling information. If you hate yourself as much as I do, you can read the paper, too. It’s awful. So many statistics to strain to extract something significant from noisy data already compromised by cultural indoctrination.

An amusing evo-psych put-down

From Kevin Bird:

“Postmodern NeoMarxist” is just an insult Jordan Peterson uses for anyone he dislikes. It’s another example of projection; you know how wingnuts like to claim that the libs call everyone a Nazi? The truth is that they like to call everyone a postmodernist or neo-Marxist.

Stephen Jay Gould is just an evo-psych boogeyman, and Geoffrey Miller is an ass. This is a great rebuttal, though:

Yep, spot on.

I do enjoy a good evolutionary psychology take-down in the morning

I read a brilliant review of what may be a brilliant book (I’ll have to read it to find out), Adapting Minds: Evolutionary Psychology and the Persistent Quest for Human Nature” by David Buller. He dismantles a ubiquitous myth among evolutionary psychologists: the idea that women crave wealthy, high-status men, that they’re using a peculiar kind of capitalist economic reasoning when they make significant life-choices about marriage and pregnancy. This appeals to certain kinds of people — incels and “alpha” males and MRAs — who love the idea of the “sexual marketplace” and the notion that with great profit comes great desirability, and the corollary that hey, if you’ve got a girlfriend, you must be a superior Chad.

The evidence, say the evolutionary psychologists like David Buss, is that if you look at polygamous societies where women’s mate choice is freed from at least one artificial constraint, that men can marry as many women as want them, they all come flocking to the highest status males, and high status males have the most offspring. The existence of harems is proof that status is what women are all seeking, and that men with harems are sexually desirable.

(I’ll give you a moment to see the obvious flaw in the reasoning before you read the book’s explanation.)

He criticizes the methodology of David Buss and confirms what I suspected but hadn’t yet researched – that David Buss ignores cultural restrictions on female choice of mates. As Buller says:

…in a well-documented study, the anthropologist William Irons found that, among the Turkmen of Persia, males in the wealthier half of the population left 75 percent more offspring than males in the poorer half of the population. Buss cites several studies like this as indicating that “high status in men leads directly to increased sexual access to a larger number of women,” and he implies that this is due to the greater desirability of high-status men (David Buss 1999 “Evolutionary Psychology the New Science of the Mind”).

But, among the Turkmen, women were sold by their families into marriage. The reason that higher-status males enjoyed greater reproductive success among the Turkmen is that they were able to buy wives earlier and more often than lower-status males. Other studies that clearly demonstrate a reproductive advantage for high-status males are also studies of societies or circumstances in which males “traded” in women. This isn’t evidence that high-status males enjoy greater reproductive success because women find them more desirable. Indeed, it isn’t evidence of female preference at all, just as the fact that many harem-holding despots produced remarkable numbers of offspring is no evidence of their desirability to women. It is only evidence that when men have power they will use it to promote their reproductive success, among other things (and that women, under such circumstances, will prefer entering a harem to suffering the dire consequences of refusal).

The fact that Buss can’t be bothered to account for virtual female slavery when proclaiming female choice is typical of the Evolutionary Psychologist approach. Their belief in the power of biology to control human behavior is so reflexive that they can’t be bothered to consider even the most glaringly obvious cultural factors impacting their claims.

It’s so typical of evolutionary psychologists that they would overlook trivial details like sexual slavery that might interfere with their thesis.

Tell me again how evolutionary psychology is not a con game

This is how evo psych works: state your hypothesis about past human societies with absolute confidence in the absence of any evidence, and then follow up with how The Lord of the Rings supports your model of a transition from a brutish form to a more gracile, effeminate form. Geoffrey Miller demonstrates:

So, the kill count competition between Legolas and Gimli is easily understood evidence of the evolution of warfare. Does that make Aragorn a transitional form?

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.