Sex with a stranger? Evolutionary psychology and sex differences in behavior

June 6, 2021 • 9:15 am

In the early days of evolutionary psychology—that is, when it was just beginning to be applied to humans—I was rather critical of the endeavor, though not so much about “sociobiology”, the application of evolutionary principles to animal behavior. A lot of the early evo psych stuff on humans was weak or overly speculative.

Since then, I’ve mellowed somewhat in light of replicated research findings about human behavior that show phenomena predicted by or very consistent with the theory of evolution. Not only are the phenomena predicted and replicated, but they are in line with what other animals show. Further, researchers have also falsified some alternative explanations (“culture” or “patriarchy” is the most common one).

I’ll add here that the disturbingly common claim that evolutionary psychology is “bogus” or “worthless” as an entire field is ridiculous, both in principle and in practice. In principle, why should human behavior, or behavioral differences between the sexes, be the one area that is exempt from evolutionary influence, especially given that we evolved in small hunger-gatherer groups for at least five million years, on top of which is overlaid a thin veneer (about 20,000 years) of modern culture? That position—that all differences between men and women, say, are due to cultural influence—is an ideological and not an empirical view. If physical differences, both between sexes and among groups, are the result of evolution, why not mental ones? After all, our brain is made of cells just like our bodies!

In practice, there are several types of human behavior that, using my mental Bayes assessment, I consider likely to reflect at least some of the workings of evolution, past and present, although culture may play a role as well. There will be an upcoming paper on these fairly solid evo-psych behaviors (I’m not an author), but I’ll highlight it when it’s published.

In the meantime, we have one behavior, described in this 2017 article from Areo Magazine, that describes a “universal human behavior” involving sex differences, and a behavior that’s likely to reflect our evolutionary heritage. Although the article is four years old, it’s worth reading. The author, David P. Schmitt, has these bona fides:

David P. Schmitt, PhD, is Founding Director of the International Sexuality Description Project, a cross-cultural research collaboration involving 100s of psychologists from around the world who seek to understand how culture, personality, and gender combine to influence sexual attitudes and behaviors.

See also his Wikipedia page, which describes him as “a personality psychologist who founded the International Sexuality Description Project (ISDP). The ISDP is the largest-ever cross-cultural research study on sex and personality.”

The article, which I recommend you read, is chock-full of data. Click on the screenshot for a free read:

The behaviors Schmitt discusses in this longish but fascinating and readable piece are summarized in the first two paragraphs (there are lots of references should you want to check his claims):

Choosing to have sex with a total stranger is not something everyone would do. It probably takes a certain type of person. Quite a bit of evidence suggests, at least when it comes to eagerly having sex with strangers, it might also take being a man. Let’s look at the evidence.

Over the last few decades almost all research studies have found that men are much more eager for casual sex than women are (Oliver & Hyde, 1993; Petersen & Hyde, 2010). This is especially true when it comes to desires for short-term mating with many different sexual partners (Schmitt et al., 2003), and is even more true for wanting to have sex with complete and total strangers (Tappé et al., 2013).

Of course this is “common wisdom” in American culture: it is the heterosexual guy who does the pursuing, and does so without many criteria beyond the lust object having two X chromosomes, and he’s still often rejected, while women are far choosier about who they mate with.

There are many studies, described and cited by Schmitt (usually using lab experiments or good-looking students on campus approaching members of the opposite sex) that show the same thing. An attractive man propositioning a woman for sex is accepted about 0% of the time, while, in the opposite situation far more than half the males accept a sexual proposition from an attractive female stranger. Here are two studies, but there are more:

In a classic social psychological experiment from the 1980s, Clark and Hatfield (1989) put the idea of there being sex differences in consenting to sex with strangers to a real life test. They had experimental confederates approach college students across various campuses and ask “I’ve been noticing you around campus, I find you to be very attractive, would you go to bed with me tonight?” Around 75 percent of men agreed to have sex with a complete stranger, whereas no women (0 percent) agreed to sex with a complete stranger. In terms of effect size, this is one of the largest sex differences ever discovered in psychological science (Hyde, 2005).

Twenty years later, Hald and Høgh-Olesen (2010) largely replicated these findings in Denmark, with 59 percent of single men and 0 percent of single women agreeing to a stranger’s proposition, “Would you go to bed with me?” Interestingly, they also asked participants who were already in relationships, finding 18 percent of men and 4 percent of women currently in a relationship responded positively to the request.

This of course jibes with the behavior of many animals (in my flies, for example, males will court almost any female, even wooing pieces of dust or small blobs of wax), while females repeatedly reject males. It’s true of primates in general, and of many animal species. And it makes evolutionary sense. If a male mates with five females instead of one, he’s likely to have five times more offspring. In the reverse situation, though, a female who mates with five males in a short period will have roughly the same number of offspring as if she mated just once. That’s because she makes a huge investment in eggs and (in some species like ducks) maternal care, and so she should be selected to be choosy about her mates, looking for a male who is fit, healthy, may have good genes, and, if there’s parental care, will be an attentive father. Since the male has far less to lose, and far more to gain, by repeatedly mating with different females, this explains the strategy of “wanton male versus choosy female” sexual preference. These are likely to be evolved sexual behaviors.

This of course is a generalization. There are certainly picky men and women who are less choosy about their partners. But it’s a generalization that holds up not only in the “choice” studies I just mentioned, but in other aspects as well. Psychological studies show that (here I quote Schmitt, bolding is his)

. . . men have more positive attitudes towards casual sex than women, have more unrestricted sociosexuality than women, and generally relax their preferences in short-term mating contexts (whereas women increase selectivity, especially for sexual attractiveness.

. . . Cognitively and emotionally, men are more likely than women to have sexual fantasies involving short-term sex and multiple opposite-sex partners, men perceive more sexual interest from strangers than women, and men are less likely than women to regret short-term sex or “hook-ups.”

Considering sexual fantasies, men are much more likely than women to report having imagined sex with more than 1,000 partners in their lifetime (Ellis & Symons, 1990).

Behaviorally, men are more likely than women to be willing to pay for short-term sex with (male or female) prostitutes, men are more likely than women to enjoy sexual magazines and videos containing themes of short-term sex and sex with multiple partners, men are more likely than women to actually engage in extradyadic sex, men are more likely than women to be sexually unfaithful multiple times with different sexual partners, men are more likely than women to seek one-night stands, and men are quicker than women to consent to having sex after a very brief period of time (for citations, see Buss & Schmitt, 2011).

Here’s a table reproduced in the Areo paper taken from Buss and Schmitt (2011), where you can find the original references. Click to enlarge.

These patterns hold in nearly all studies in different parts of the world. That in itself suggests that culture may play an insignificant role in the difference I’m discussing.

Now if you’re thinking hard, you can think of at least four non-evolutionary explanations for these behaviors (I’ve combined disease and pregnancy in #3 below). Both, however, have been shown to be unlikely to be the major explanation for the sex difference in choosiness.

1.) Patriarchy: These could be cultural differences enforced by the patriarchy and socialization. Why a patriarchy exists itself may be evolutionary (e.g., males are stronger and thus can control females more easily than the other way around), but male dominance itself is not the explanation we’re testing here. Schmitt explains why (beyond observed cultural universalism), this is unlikely to explain the entire behavioral difference (all emphases are the author’s):

For instance, Schmitt (2015) found sex differences in the sociosexuality scale item “I can imagine myself being comfortable and enjoying ‘casual’ sex with different partners” were largest in nations with most egalitarian sex role socialization and greatest sociopolitical gender equity (i.e., least patriarchy, such as in Scandinavia). This is exactly the opposite of what we would expect if patriarchy and sex role socialization are the prime culprits behind sex differences in consenting to sex with strangers.

How can this be? Why are these sex differences larger in gender egalitarian Scandinavian nations? According to Sexual Strategies Theory (Buss & Schmitt 1993), among those who pursue a short-term sexual strategy, men are expected to seek larger numbers of partners than women (Schmitt et al., 2003). When women engage in short-term mating, they are expected to be more selective than men, particularly over genetic quality (Thornhill & Gangestad, 2008). As a result, when more egalitarian sex role socialization and greater sociopolitical gender equity “set free” or release men’s and women’s mating psychologies (which gendered freedom tends to do), the specific item “I enjoy casual sex with different partners” taps the release of men’s short-term mating psychology much more than it does women’s. Hence, sex differences on “I enjoy casual sex with different partners” are largest in the most gender egalitarian nations.

Overall, when looking across cultures, reducing patriarchy doesn’t make these and most other psychological sex differences go away, it makes them larger (Schmitt, 2015). So much for blaming patriarchy and sex role socialization.

2.) Fear of injury. In general, men are stronger than women (this is almost surely the result of evolution affecting competition for mates). Perhaps women are leary of accepting propositions from unknown men because they might get hurt, as do many prostitutes. But several studies show that safety alone cannot be the whole explanation:

Clark (1990) was among the first to address the issue of physical safety. He had college-aged confederates call up a personal friend on the phone and say “I have a good friend, whom I have known since childhood, coming to Tallahassee. Joan/John is a warm, sincere, trustworthy, and attractive person. Everybody likes Joan/John. About four months ago Joan/John’s five year relationship with her/his high school sweetheart dissolved. She/he is was quite depressed for several months, but during the least month Joan/John has been going out and having fun again. I promised Joan/John that she/he would have a good time here, because I have a friend who would readily like her/him. You two are just made for each other. Besides she/he has a reputation as being a fantastic lover. Would you be willing to go to bed with her/him?” Again, many more men (50%) than women (5%) were willing to have sex with a personally “vouched for” stranger. When asked, not one of the 95% of women who declined sex reported physical safety concerns were a reason why.

3.) Fear of pregnancy and/or disease. Since venereal diseases can be passed in both directions, I’m not sure that disease is a good explanation, though perhaps women are more likely to get serious disease than are men. As far as pregnancy is concerned, there’s at least one study showing it can’t be the sole factor:

Surbey and Conohan (2000) wondered whether worries of safety, pregnancy, stigma, or disease were what was holding women back from saying yes to sex with a stranger. In a “safe sex” experimental condition, they asked people “If the opportunity presented itself to have sexual intercourse with an anonymous member of the opposite sex who was as physically attractive as yourself but no more so (and who you overheard a friend describe as being a well-liked and trusted individual who would never hurt a fly), do you think that if there was no chance of forming a more durable relationship, and no risk of pregnancy, discovery, or disease, that you would do so?” On a scale of 1 (certainly not) to 4 (certainly would), very large sex differences still persisted with women (about 2.1) being much less likely to agree with a “safe sex” experience with a stranger compared to men (about 2.9).

So, sex differences in agreeing to sex with strangers are not just a matter of safety issues, pregnancy concerns, slut-shaming stigma, or disease avoidance. Controlling for all of that, researchers still find large sex differences in willingness to have sex with a stranger.

There’s a lot more in this paper, including Schmitt’s critique of the two papers cited widely as disproving the “pickiness” hypothesis. Both papers, however, suffer from extreme methodological flaws, and in both cases the results support the “pickiness” hypothesis when the flaws are corrected.

You can read the hypothesis and judge for yourselves, but I think this is one of the best examples we have of evolutionary psychology explaining a difference between men and women in behavior*. As I said, it’s shown up throughout the world in different cultures, it’s paralleled in many species of animals, alternative explanations fail to explain the data, other, unrelated data support at least a partial evolutionary basis of the choice difference, and the few papers that claim to disprove it wind up actually supporting it.

Aside from “universal” behavior like sleeping, eating, or wanting to reproduce, which are surely instilled in us by evolution (and nobody questions those), we shouldn’t ignore differences between groups, especially the sexes, as having an evolutionary origin. It’s likely that morphological differences between geographic populations, like the amount of melanin in the skin, are adaptive responses to natural selection, so why is behavior the one trait that is always off limits to evolutionary explanation? It’s ideology, Jake.

h/t: Steve Stewart-Williams

*As a reader points out below, and even more obvious evolutionary difference is that the vast majority of men are sexually attracted to women, and vice versa. That would be hard to explain as a result of the patriarchy or of socialization.

An evolutionary psychology book that shows the discipline’s value—but not the value of memes

September 15, 2020 • 9:00 am

I’ve just finished reading Steve Stewart-Williams’s recent book The Ape That Understood the Universe (Cambridge University Press, revised edition 2019). I recommend it highly as a good way to get not only an introduction to evolutionary psychology, but also to see why the discipline is worthwhile and why its detractors are often misguided. Click on the screenshot if you want to buy it from Amazon US.

I have to hedge my encomiums a bit, because while most of the book—the first part that deals with evolutionary psychology—is excellent, the second bit, only the last 64 pages, is weaker. That’s the bit that deals with memes, the popular but, I think, misguided view that we can understand human cultural evolution by assuming it’s propelled by memes, “units of culture” first dreamed up by Dawkins in The Selfish Gene. While memetics sounds good at first glance, and has become incorporated into popular jargon as “an item that’s gone viral on the Internet”, I have always questioned its value as a way to understand how ideas and objects spread in human culture—indeed, supposedly creating human culture. I explained my criticisms in a 1999 Nature book review of Susan Blackmore’s book The Meme Machine, and won’t reiterate them at length here.

But the biggest part of the book is well worth reading, particularly because Left-wing biologists have denigrated evolutionary psychology at length, calling it not only worthless, but meaningless. I won’t name these miscreants, but suffice it to say that their motivations are largely ideological: they think that if human behavior—particularly behavioral differences between groups and especially between men and women (but also behavioral “universals”)—are partly instilled in our genome by natural selection, then that will justify xenophobia, misogyny, and all kinds of bigotry.

This claim isn’t true, of course. As I’ve mentioned repeatedly, to say that our evolutionary past justifies how people should treat others, or construct a morality, is deeply misguided: “the naturalistic fallacy.” And to accept that natural selection has molded human bodies and physiology, and has done so within the last 10,000 years (see here), but then to deny that natural selection has affected human behaviors, including differences between the sexes that sometimes parallel those seen in animals, is a nonsensical and unparsimonious view.

Further, evolutionary psychology as a discipline is neither worthless, unproductive, nor tautological. After describing how natural selection operates on genes (including kin selection and the production of cooperative behaviors), Stewart-Williams takes up some topics in evolutionary psychology and shows that the discipline has indeed produced testable and confirmed hypotheses, particularly those involving aspects of human sexual behavior as well as behavior toward kin and group-mates (“altruism”).

Stewart-Williams is no uncritical booster of evolutionary psychology, readily admitting that some of its advocates have gone overboard. But you don’t throw out the baby with the bathwater, and in an appendix called “How to win an argument with a Blank Slater”, Stewart-Williams takes up and rebuts some of the most common criticisms of the discipline (e.g., “evolutionary psychology is the latest incarnation of genetic determinism”, “hypotheses in evolutionary psychology are either just-so stories or are unfalsifiable”, and so on). Hypotheses in the discipline are often testable and falsifiable, and one of the strongest parts of this book is the description of data that support hypotheses about the evolution of behavior, as well as some description of tests that have failed. Like Darwin, Stewart-Williams is always anticipating readers’ queries and criticisms, and addresses them throughout the book.

The discussion of human “altruism”, always a puzzling topic, is also quite good, with Stewart-Williams lucidly describing the various ways what we think of as “selfless behavior” could evolve (kin selection, small-group tit-for-tat strategies, and group selection, which he considers unlikely). All in all, I strongly recommend you read at least the first 218 pages on evolutionary psychology, as well as Appendix A on arguing with Blank Slaters.

You should also read the last chapter on memetics (“The Cultural Animal”), but do so with an especially critical eye. Although Stewart-Williams’s aim in the book is to explain human behavior and society as a result of both biological and cultural evolution, he’s much more successful with the former than the latter. That’s not to say that he doesn’t have good insights into cultural evolution, for he does. It’s just that the addition of “memes” doesn’t, in my view, add much.

I’ll give just one example. Most of us love apple pie and ice cream, and Stewart-Williams considers this a meme whose spread needs explanation. The classical explanation of memetics is that ideas spread when they parasitize human brains and have features that are good for the memes themselves to spread, though those features may not be adaptive for individuals or society (he uses smoking as one example). So it goes with apple pie à la mode:

. . . the ultimate criterion which determines whether a meme will spread is not whether it benefits us or our groups, but whether it benefits the meme itself.

Two examples will illustrate the point. [JAC: I give just the first.] The first is apple pie and ice cream. The apple-pie-and-ice-cream meme has prospered in human societies because it powerfully activates the brain’s pleasure centers—more powerfully, in fact, than anything in our natural environment. Eating too much of the stuff isn’t good for us, but that’s irrelevant. The meme proliferates, not because it’s good for us but purely because it’s good for itself—purely, that is, because it’s good at proliferating. To be clear, it doesn’t want to proliferate or know what’s good for it, any more than genes do. It’s apple pie! The idea is simply that if we want to understand which memes come to predominate in a culture, then rather than looking at how memes affect our fitness or the fitness of our groups, we need to look at how they affect their own chances of being passed on.

But to assert that the apple-pie-a-la-mode meme has properties that make it good at proliferating is simply tautological, and not in the way that the spread of genes is said to be tautological. What, exactly, about this meme helps it spread itself among Americans or Brits? What makes it good for itself? As far as I can see, nothing. What makes it spread is simply that apple pie and ice cream taste good, and taste better than alternatives like, say, donuts and ice cream. While Stewart-Williams admits that this dessert “activates the brains’s pleasure centers,” the real explanation for why this dessert “meme” is popular would involve understanding why it tastes better than alternatives. As I wrote in my Nature review of Susan Blackmore’s book:

. . . Blackmore’s enterprise has two fatal flaws. First, she has got the chain of causation backwards. The claim that memes created major features of humanity is equivalent to the claim that the main force driving the development of better computers has been the self-propagation of software. In reality, computers are usually designed for speed and capacity, which then permits the development of new software. Similarly, the self-replication of memes does not mould our biology and culture; rather, our biology and culture determine which memes are created and spread. What a world of human psychology is obscured by Blackmore’s mantra, “If a meme can get itself successfully copied it will”! To me, memetics boils down to the following obvious theory: ideas tend to spread if they cater to our desires to have love, comfort, pleasure, power, sex, the attention and admiration of others, a meaningful life and a way to evade the awful fact of mortality.

This brings us to the biggest problem: memetics seems completely tautological, unable to explain why a meme spreads except by asserting, post facto, that it had qualities enabling it to spread. One might as well say that aspirin relieves pain because of its pain-relieving properties. The most interesting question — why some memes spread and not others — is completely neglected. Why did Christianity take hold during the waning days of the Roman Empire? You won’t find the answer, or any way to attain it, in memetics. (This, by the way, makes memetics utterly unlike biological evolution. The spread of genes through natural selection is not tautological because one can predict their fate through their known effects on replication and the reproduction of their carriers.)

Nothing is gained in understanding the spread of apple pie and ice cream by considering it a “brain parasite,” which Stewart-Williams does.

I think Stewart-Williams recognizes this problem with memetics, for he deals with it in Appendix B: “How to win an argument with an Anti-Memeticist”. Here we find the following passage, which starts with a criticism of memetics in italics and then the his rebuttal in plain text.

The hallmark of a good scientific theory is that it generates research: it makes novel predictions about the world, which lead scientists to make otherwise unexpected discoveries. Memetics, however, has been woefully unsuccessful on this front. Indeed, the field’s flagship journal, The Journal of Memetics, had to close its doors because it didn’t get enough submissions.”

[Stewart-Williams’s answer]: This is the “if you’re so smart, why aren’t you rich?” criticism. Of all the criticisms on offer, it’s probably the one that worries me most. In the end, though, I think it fails. It is certainly true that memetics has yet to deliver much in the way of new research. It’s also true that many specific meme-based explanations have yet to be adequately tested. However, when it comes to evaluating a theory or explanation, what we ultimately want to know is not how many publications it’s generated, or how many surprising discoveries, bur rather something more basic: whether or not the theory is true. That, in the final analysis, is what science is all about. And despite the current research shortfall, there’s good reason to believe that, at least in its general outline, memetics is indeed a true and accurate theory.

But how can we know if a theory is true if it doesn’t propose tests or potential falsifications? Stewart-Williams tentatively accepts the truth of memetics because he says it makes sense: cultural entities appear “designed to benefit themselves”, even if they harm individuals or groups. (Yes, too much pie is bad for you, or, as the jolly Almus Pickerbaugh said in Arrowsmith, “too much pie makes pyorrhea.“) But how, exactly, does the apple-pie-and-ice cream “meme” benefit itself? Can you predict this in advance from simply the existence of the combination? Well, perhaps you could predict it if you knew how its gustatory constituents interacted with human brains, but that’s a psychological explanation that has nothing to do with the “self spreadability” of the pie-and-ice cream meme.

In the end, you have to judge whether a theory is true based not on intrinsic plausibility but on whether it survives empirical tests. In my view, the empirical “tests” of memetics boil down to post facto explanations of why something spread based on some characteristic of the cultural unit itself. And here memetics has, as Stewart-Williams admits, failed. It doesn’t explain much and doesn’t seem falsifiable because memeticists always seem able to confect a reason why something had to spread, independent of human tastes, needs, or psychology. It is intrinsically an unfalsifiable theory.

I’ve written a lot about memes because it’s a bugbear of mine, not because it’s the major topic of Stewart-Williams’s book. It isn’t. And so I recommend that you read the book, if for no other reason than to see why the critics of evolutionary psychology are largely misguided. But you’ll also learn a lot about how natural selection works, and how it’s forged an appreciable part of human behavior.

Steve Stewart-Williams on the value of evolutionary psychology

August 26, 2020 • 10:15 am

When I give talks about why Americans reject evolution so frequently, I refer to Steve Stewart-Williams’s excellent book from 2010: Darwin, God, and the Meaning of Life: How Evolutionary Theory Undermines Everything you Though You Knew. It goes through reason after reason why evolution not only undermines our ideas, but why that undermining makes people resistant to evolutionary biology and its conclusions. It explained to me, for instance, why 27% of American Catholics are creationists, embracing Biblical literalism despite the fact that the Church itself explicitly accepts evolution. Those people, like many, just can’t get past the naturalistic and non-human-centric implications of evolution. The book is like a bucket of cold water tossed on the idea that evolution doesn’t conflict with religion.

Steve has a newer book, published in 2018 (click on screenshot below to go to Amazon site). I haven’t yet read it, though it’s coming to me through my library, but it’s apparently a discussion of the evolution of culture (“evolution” that’s both genetic and cultural), as well as a discussion of the merits of and problems with evolutionary psychology.

Stewart-Williams is an associate professor of psychology at the University of Nottingham Malaysia Campus, and I’ve written about some of his work here, describing why he thinks that the difference between human males and females in levels of aggression has a substantial evolutionary basis. But, as the interview below shows, in which he speaks with Pablo Malo at the site La Nueva Ilustración Evolucionista (“The New Evolutionary Enlightenment”), Stewart-Williams doesn’t accept whole hog all the claims of evolutionary psychology, and is sometimes quite critical of them. In other words, Stewart-Williams’s attitude towards the discipline is similar to mine. Read the interview by clicking on the screenshot below. There’s an English translation so you don’t have to use Google translate except for the introduction (or if you speak Spanish):

Stewart-Williams’s take on evolutionary psychology also differs from that of biologists on the “progressive” left who reject evolutionary psychology as a whole, dismissing it as a farrago of “just-so stories” and untested (and untestable) hypotheses. You can see this attitude, for instance, in people like blogger P. Z. Myers, who should know better, and his minions. Yes, the discipline has its “soft underbelly,” as I’ve described, but it’s also led to informative insights, and simply cannot be swept away with unwarranted ridicule. Dismissal of evolutionary psychology as a whole (see another dismisser below) comes not from a scientific attitude, but an ideological one: if human behavior evolved over millions of years, just like human bodies and physiology (one can’t deny the latter), then perhaps we are partly slaves to biological determinism, and, worse, behavioral differences between men and women might be in part the result of evolution.

I think the evidence for evolved differences is pretty solid, but blank-slaters, who happen to populate the progressive Left, deny this determinism because they mistakenly think that evolved differences somehow imply moral differences. As Steve Pinker showed in his book The Blank Slate, and I’ve said many times, the idea that evolution tells us what is right and wrong is a fallacy—the “naturalistic fallacy”.

But I digress. I’ll just say once more that the blatant dismissal of evolutionary psychology as a discipline is not only unwarranted, but ignorant and ideologically based. To think that human bodies are the product of evolution but human minds are not can only be the product of some overweening and blinkered ideology.

On to the interview. It’s in both Spanish and English.. I’ll highlight the main points in bold, and any quotes from Steve will be indented:

Some of evolutionary psychology is weak and “silly”, and can comprise “just-so stories”.

A third reason I decided to write Ape was that I wanted to present a somewhat circumspect view of evolutionary psychology – one that met the critics halfway on a number of issues. This includes the common criticism that evolutionary psychologists too often overextend the adaptationist mode of explanation, seeing adaptations in all sorts of psychological and behavioral tendencies that probably aren’t adaptations at all. My response to this criticism is: Guilty as charged. Evolutionary psychologists have sometimes put forward some pretty silly adaptationist hypotheses, and we need to be a bit more careful about that

But a lot of it is sound, though not “proven”—but of course no science is “proven”. We just accrue more or less confidence in hypotheses as we do more tests. So the declarations of people like philosopher Subrena Smith, who declared that doing evolutionary psychology was “impossible”, are badly mistaken. (I discussed Smith’s paper here, and Steve Pinker’s ideas about it here.)

Steve:

Evolutionary psychology certainly isn’t perfect, but I have to say I wasn’t particularly impressed with [Smith’s] critique. The idea that that EP is impossible – not just difficult, but impossible – strikes me as so extreme that I’m a little surprised so many people took it so seriously. It also strikes me as awfully convenient that, of all the sciences, the one we can rule out a priori, on purely logical grounds, just happens to be one that many people dislike and object to for explicitly political reasons.

Smith’s argument is basically a sophisticated reboot of the old retort that “behaviour doesn’t fossilize.” She claims that there’s ultimately no way to show that the psychological tendencies underpinning people’s behaviour today evolved in prehistoric times to perform the same functions that they currently perform, and thus that evolutionary psychology is impossible in principle.

Is she right? Well, one reason to doubt that evolutionary psychology is impossible is that… people are already doing evolutionary psychology: They’re gathering evidence bearing on evolutionarily informed hypotheses, and this evidence nudges up or down our confidence that these hypotheses are accurate. Sure, no one has provided evidence that proves any hypothesis in evolutionary psychology with the certainty of a mathematical proof. But that’s true of every claim in science. Scientists can only ever nudge our confidence up or down. Perhaps this is harder in EP than in some fields (although the replication crisis in psychology and elsewhere suggests that it’s not as easy as we thought in any field). But saying that it’s harder is very different than saying that it’s impossible.

And in some cases, it isn’t even particularly hard. Consider hunger. Strictly speaking, we can never say with 100% certainty that this psychological capacity evolved in our prehistoric ancestors, or that it had the same function back then as it does today (i.e., motivating us to seek and consume food). But it seems reasonable to think that it did. Indeed, it seems unreasonable to think otherwise – unreasonable, in other words, to think that our ancestors did not experience hunger or that the primary function of hunger back then was unrelated to eating. And if you accept that, I think you also have to accept that there’s no in-principle reason to reject any and all evolutionary psychological hypotheses, even if others are more difficult to evaluate. For a more detailed response to Smith’s paper, see Ed Hagen’s excellent post on the topic.

Few evolutionary psychologists now accept two views they’re often accused of: “Massive modularity” (the brain comprises various semi-independent modules that code for different behaviors), and the “Environment of evolutionary adaptedness”: the idea that our behaviors all show adaptations to the life of our ancestors on the African savannas. The latter, at least, would be foolish given the evidence that humans have undergone palpable evolutionary change in the last 10,000 years. Stewart-Williams prefers that evolutionary psychologists just analyze human behaviors using well-established evolutionary principles like kin selection, parental investment, reciprocal altruism, and the like.

Refutations of the “Cinderella Effect”: the demonstration that parents are more brutal toward their stepchildren than their biological children, are weak. (These were mostly raised by Hans Temrin.) According to Stewart-Williams, the data come down pretty much in support of the Cinderalla Effect. If further studies buttress those data, it would be good evidence for an evolutionary-psychology explanation based on relatedness and parental investment. It makes sense that you’d treat your biological children better than those unrelated to you, and you might even abuse the latter if it favors the prospects of the former. (Remember, lions that invade a pride immediately kill all the cubs from the mothers, and then inseminate the mothers, yielding cubs that are related rather than “step-cubs”.)

The idea of memes hasn’t been that productive in understanding human cultural evolution, but there are a few suggestive examples of memes evolving simply because they have self-propagating characteristics. One of these examples involves witch hunts, and was published last year by Hofhuis and Boudry. I haven’t read it yet, but I’ve been a pretty severe critic of “memetics.”

The Himba people of Namibia have a 48% rate of non-paternity; that is, half the children in a family aren’t fathered by the “father.” Isn’t that a refutation of evolutionary theory? Stewart-Williams explains why we’d sometimes expect these anomalies.

Disparities in representation of males vs. females in different areas don’t always demonstrate sexism and bigotry, as many assume. They could just be differences in preference, and perhaps some of these are the result of evolved behaviors. I’ve made this point many times before, but it still goes over the head of many “progressives”, who fail to realize that there is, for many cases of unequal representation, a competing hypothesis to the idea of “structural discrimination.”

Here’s what Steve says about that in response to a question:

What are you working on now? What mystery would you like to unravel next?

I’m working on two main projects at the moment. One is a theoretical paper with Lewis Halsey, looking at the causes of gender disparities in STEM. As everyone knows, men outnumber women in certain areas of STEM, including mathematics, computer science, and physics. As everyone also knows, the most common explanations for the gender gaps are discrimination and socialization. We argue, in contrast, that although discrimination and socialization are part of the story, they’re not the whole story. We make two main claims in our paper. The first is that factors other than discrimination contribute to gender gaps in STEM; these include, in particular, average sex differences in interests and life priorities. The second is that these average differences aren’t due entirely to socialization. Socialization plays an important role, but the differences are also partly inherited.

People sometimes assume that if you admit a role for biological factors in shaping STEM gender gaps, you must think nothing should be done about those gaps. But that’s not our view. We are wary of overly coercive fixes, such as offering people monetary or other incentives to make career choices they wouldn’t otherwise make, and affirmative-action policies that, in effect, discriminate against men and lead people (including the benefactors of such policies) to secretly wonder whether they really earned their success. But that doesn’t mean we should do nothing. We should let young people know about all the science careers on offer, and make clear that these are options that women as well as men should consider. We should make sure we highlight the scientific achievements of both sexes, rather than focusing unduly on men. We should encourage people to accept and support women (and men) who make gender-atypical choices. We should put policies in place that reduce the possibility of bias against either sex, including gender-blind evaluation of job applications, research grants, and the like. And we should do what we can to make science careers compatible with the demands of motherhood (and fatherhood).

Having done all that, though, we should respect the choices that people make about their own lives and careers, even if this doesn’t result in perfect gender parity. In other words, we should aim for equality of opportunity, rather than equality of outcome. People are ultimately going to be happier if they pursue the careers that most interest them.

There’s a lot more to the interview than this, so if you want a level-headed take on evolutionary psychology, I’d recommend that you have a look at the interview, and perhaps read Steve’s latest book.

Are human facial expressions universal in which emotions they express?

August 24, 2020 • 1:00 pm

The latest issue of Science Advances has a provocative and clever piece of research aimed at answering a long-standing question—one considered by Charles Darwin himself: are the facial expressions associated with human emotions universal across all cultures? And, if so, is that the result of evolution? The paper suggests that, at least for a limited set of emotions, the answer is yes to both questions. You can read the paper by clicking the screenshot below, or reading the pdf here. The full reference is at the bottom.

Cowen and Keltner note that there have been a fair number of attempts to answer this question, all involving going to remote areas where there is little contact with Westerners, and seeing if people in those areas match photos of Western expressive signals (joy, anger, sympathy) with similar words in their native language. The results have been mixed. That, one would think, already suggests that perhaps facial expressions aren’t universal. (Cultural similarities could be due to either cross-cultural transmission of expressivity, or to a common evolutionary heritage, but dissimilarities among different populations already suggest that culture can’t cause similarities.)

However, the authors suggest these tests are not dispositive, and suggest a better way to see if expressions are universal. What they did was to look at ancient Mesoamerican artworks that depict facial expressions associated with different situations, isolated the facial expressions, got modern observers to guess the emotions depicted, and then asked whether Westerners would judge those expressions to be ones appropriate to the situation depicted by the artwork. If there was a correlation between the judgements of which emotions were shown on faces, and those that other people guessed would appear in the situations depicted in the sculptures, this would suggest (but not prove) that expressions are not only universal, but perhaps universal because evolution made them universal.

The authors examined tens of thousands of Mesoamerican artifacts (going back to 1500 B.C.) archived by museums, and found 63 pieces of art that met their three criteria for this study:

subjects were portrayed “within one of eight identifiable contexts” (torture, being held captive, carrying a heavy object, embracing another person, holding a baby, in fighting position, playing a ball sport, and playing music). Examples of each of these are given in the figure below.
The facial expressions could be clearly visible.
The artworks (sculptures and vessels) were deemed authentic by authorities.

Here are examples of the eight contexts for emotion; see the caption for details:

(From paper): Fig. 1 Ancient American sculptures with discernible faces and contexts. (A) Captive from Tonina archeological site (Mexico, 690–700 CE). Photo credit: Mauricio Marat, Instituto Nacional de Antropología e Historia. https://www.inah.gob.mx/images/boletines/2016_215/demo/#img/foto5.png (1 July 2019). (B) Tortured, scalped prisoner from Campeche (Mexico, 700–900 CE). Baltimore Museum of Art, Kerr Portfolio 2868, photo by J. Kerr. (C) Maya man carrying large stone (Mexico, 600–1200 CE). Kerr Portfolio 8237, photo by J. Kerr. (D) Joined couple (Mexico, 200–500 CE). Los Angeles County Museum of Art (LACMA) AC1996.146.21, gift of C. M. Fearing. (E) Maya woman holding child (600–800 CE). Princeton University Art Museum 2003-26, gift of G. G. Griffin. (F) Kneeling Maya warrior with facial tattoos and shield (Mexico, 600–800 CE), detail. Earthenware and pigment, 15.9 cm by 10.8 cm. Fine Arts Museums of San Francisco 2009.38.2, gift of G. Merriam and J. A. Merriam. (G) Maya ballplayer (Mexico, 700–900 CE). University of Maine HM646, William P. Palmer Collection. (H) Colima drummer (Mexico, 200 BCE–500 CE). LACMA, Proctor Stafford Collection, purchased with funds provided by Mr. and Mrs. Allan C. Balch.

They then isolated the faces from the contexts so that the modern subjects could just look at the faces but not see what the subject was experiencing in the artwork. The 325 subjects were asked them to describe the facial expressions using 30 categories of emotion (e.g., “awe”, “anger”, “shame”, “fear”, and so on and 13 “affective features” like “arousal” and “dominance” (see categories in figure below).

Independently, they asked 114 different subjects, also modern Westerners, to judge what emotions they would expect someone to show in each of the eight situations above. These people were not shown the artworks but simply given the eight situations verbally and asked what emotions you’d expect people to evince. They then correlated the first subjects’ judgments on what emotions were portrayed by the faces with the expectation of what emotions should be shown from the eight situations, described in words, chosen for analysis.

Here are the correlations between the “read” of subjects from looking just at the faces with the emotions expected judged from subjects looking at the context described in words.

(from paper): Fig. 2 Accordance between emotions perceived in sculptures’ isolated face depictions and Western expectations for the emotions that unfold in eight portrayed contexts. To calculate the accordance between sculptures’ expressions and Westerners’ expectations, we correlated the participants’ average judgments of the emotions and affective features associated with each isolated face and each context across the eight contexts and divided by the maximum attainable correlation given sampling error (see Materials and Methods). Correlations are generally positive, indicating that facial muscle configurations portrayed in ancient American sculptures align, in terms of the emotions they communicate to Westerners, with Western participants’ expectations for the emotions that unfold in different contexts. Error bars represent SEs. Here, we excluded 10 emotions and 1 affective feature used seldom enough that <1/3 of the covariance in judgments was explainable, as a result of which SEs were very large.

Correlations above zero are positive; that is, the expectations of what you’d feel aligned with the subjects’ “read” of the artworks’ faces. As you see, of the 32 emotion categories assessed, 27 had correlations above zero, which alone says something (if there were no correlation, roughly half of the values would be above zero and half below). More important, only six of the 27 positive correlations had standard errors that overlapped zero, or “no correlation”; the rest were statistically significant.

This shows that, in general, the emotions expected by people hearing about the eight contexts for the artwork were those actually discerned by people who looked at the faces of the artwork. And that means that the emotions we expect to see in a modern situation were those that people read from artwork of ancient civilizations. This is turn suggests that at least some facial expressions are “universal”, and people can read them fairly accurately, even in sculptures, as reflecting what people are feeling in a situation. Because these cultures were far removed from ours, this also suggests that the facial expressions weren’t culturally inherited across the ages—that is, we don’t learn the expressions to show determination or distress or the other emotions from others, but express them innately.

One could, I suppose, argue that the Incas and Mayans simply passed on their facial expressions culturally to us as their descendants, but that’s a big stretch since the route for that kind of cultural transmission is dubious: we’re not the descendants of these Mesoamericans. Alternatively, the expressions could have been culturally inherited from our mutual ancestor who lived at least 60,000 years ago when H. sapiens left Africa to populate the world. If you’re a blank-slater, that’s the argument you’d make.

But it seems more plausible to me that smiling and scowling and showing distress and pain are innate features of our behavior, though I can’t adduce hard evidence for it except that a). babies who haven’t been socialized to show facial expressions of joy or distress still show easily interpretable expressions, presumably before they’re socialized; b). other primates have readable facial expressions without our kind of culture; and c.) one can make a plausible evolutionary hypothesis that humans might have evolved to show expressions that other humans could read: “honest signals.” None of this adds up to a strong evolutionary-psychology argument, but one can agree, from the results above, that there is some universality across millennia in how humans show emotions on their faces.

Finally, the authors used a method called “principal preserved components analysis” to gather in one basket the main “dimensions” (combinations of emotions) that best explain the correlations shown above. From this they determined that three combinations of factors combine to explain at least five types of facial expressions on sculptures. Those expressions, the ones most easily seen as “universal, are these:

“pain”, often in the context of torture
“determination”/”strain”, in sculptures showing heavy lifting
“anger”, usually in sculptures depicting combat
“elation”, seen in “contexts of familial or social touch”, and
“sadness”, as in being held captive after defeat.

The paper has other analyses, but these are the main conclusion. The authors also give several caveats, and you can have a look at those.

The tentative takeaway lesson is that, even after millennia, we can pretty accurately read the facial expressions of people from different cultures. That is, there are some universals, at least between ourselves and Mesoamericans, in the expression of emotions. Whether that be the result of cultural inheritance or a universal code for expression that resides in our DNA (or a combination of these factors) can’t yet be discerned, but I’m betting on a largely biological-determinism explanation. And so are the authors, at least judging from their final paragraph:

The present results thus provide support for the universality of at least five kinds of facial expression: those associated with pain, anger, determination/strain, elation, and sadness. These findings support the notion that we are biologically prepared to express certain emotional states with particular behaviors, shedding light on the nature of our responses to experiences thought to bring meaning to our lives.

Here are a few more faces and the contexts in which they appear (see paper for explanation), but I think you can guess pretty well.

h/t: cesar
____________

Cowen, A. S. and D. Keltner. 2020. Universal facial expressions uncovered in art of the ancient Americas: A computational approach. Science Advances 6:eabb1005.

Steve Pinker weighs in on the “evolutionary psychology is impossible” paper

May 19, 2020 • 1:30 pm

After I wrote my critique of Subrena Smith’s anti-evolutionary-psychology paper this morning—hers titled “Is evolutionary psychology possible?”—I sent the link to Steve Pinker, who’s quarantining on Cape Cod. He wrote back with some nice words of approbation, but added a few points. I thought these points were good, relevant and, as the first two weren’t made by either me or critic Edward Hagen, I asked Steve if I could quote him. He said yes. So add these criticisms to those leveled this morning. (Steve’s words are indented.)

All your points are exactly right. The motive seems to be the slipshod politicizing I exposed 18 years ago in The Blank Slate: if we’re blank slates, there can’t be differences between races, which would make racism impossible; therefore to combat racism we must believe that humans are blank slates. It fails both in philosophical coherence (racism is not an empirical hypothesis that might be shown to be true or false) and in accuracy — most evolutionary psychologists argue for a universal human nature. Also, a philosophical argument against evolutionary explanations in psychology ultimately falls apart when it unwittingly “refutes” even the most unexceptionable evolutionary explanations, such as sexual desire or protectiveness of children. And ironically, though this argument claims to be based in the philosophy of science, it seems unaware that within that field “argument to the best explanation” is generally considered the only means by which science of any kind is done — science never makes apodictic pronouncements based on a prior list of methodological precepts.

A couple of other observations [about Smith’s argument]:

—“Massive modularity” [JAC: a term Smith uses as an inherent part of “Evolutionary Psychology”] is not a term that was ever, to my knowledge, used by an evolutionary psychologist. As far as I know it was coined by that foe of natural selection, the late Jerry Fodor, as a term of abuse (and partly to protect the brand of Modularity, which Fodor introduced to philosophy and cognitive psychology in 1983). I’ve always argued that “module” is a misleading metaphor; we should be thinking about specialization. The brain isn’t spam, but the specialization of information-processing systems, like that of organ systems, needn’t be into encapsulated modules (Fodor’s definition); the systems have to talk to each other, share subroutines, pass information back and forth, and so on, just like the circulatory system and the digestive system do.

—This is a point in the fine print of EP, forgotten even by many of its practitioners, but the Environment of Evolutionary Adaptedness should not be confused with the Pleistocene or the hunter-gatherer lifestyle — it’s a time-weighted composite of selection pressures right up to the present (since natural selection never sleeps). We’ve spent more of our time as humans in a hunter-gatherer lifestyle, and, ironically for the PC police, the simplifying assumption that “EEA = Pleistocene” guarantees human biological equality, since we were all hunter-gatherers then, whereas different groups transitioned to agriculture and civilization at different times subsequent to then. And so if we continued to evolve since then, some groups could be more biologically adapted than others to literacy, settled life, governance, and so on. So the Pleistocene-EEA idealization is simple and convenient. But it’s far from necessary, and I think is an impediment, because it requires being more gratuitously committed to savannah-caveman scenarios. Many selection pressures are more or less unchanged since the dawn of the Holocene — paternity uncertainty, infant care, avoiding toxic foods, securing allies, etc. And for many others the most dramatic dividing line is not Pleistocene-Holocene or hunter-gatherer/agriculture, but urban, educated modernity (knowledge of science and statistics, professional employment, universal information, access to the legal system, modern medical care) versus every other lifestyle. An American 19th century farming village, or a favela or peasant society in the developing world, has pretty much the same face-to-face social network, with a pre-scientific knowledge base and a remoteness from legal and professional institutions, as a hunter-gatherer society 10K years ago. What’s key is avoiding the assumption that humanity is adapted to a modern urban or suburban college-educated lifestyle, not assuming that we have the same brains as hunter-gatherers (whether or not we in fact do).

—I think that one important direction of evolutionary psychology (and medicine, and biology in general) is to look for statistical signs of selection in the genome. This showed that the modern version of FOXP2, involved in language and speech, was a target of selection (though not on the recent rapid sweep originally hypothesized, probably earlier). But this method works best in the rare cases where single genes with large effects can be identified. Now that we know that virtually all behavioral variation is under the control of many genes with minuscule individual effects, I wonder whether there are techniques that can assess signs of selection across an entire vector of genes rather than individual genes.

Did a philosopher make evolutionary psychology impossible?

May 19, 2020 • 10:00 am

Subrena Smith, an assistant professor of philosophy at The University of New Hampshire, has made a bold claim in the journal Biological Theory (click on screenshot below). She claims to have found a fatal flaw in the practice of evolutionary psychology, one that renders the entire discipline “impossible”. Click below to read the article for free:

Here’s the abstract in which she identifies the flaw (there are actually more than one) and pronounces the discipline “impossible”:

Her article has garnered quite a bit of approbation among those who think that evolutionary psychology is a worthless enterprise, including, apparently, the site Gizmodo, which published a worshipful interview with Smith (click on screenshot below to read it):

Well, has she done what she aimed to: brought down an entire discipline? My judgment is “no—certainly not.” She doesn’t even come close. What she does is list a set of standards that, Smith thinks, must be met for an evolutionary psychology explanation to be credible, and these standards are so rigorous and hard to meet that no study has met them or can meet them. Ergo, evolutionary psychology—done the way she wants—is “impossible.”

I believe that her overly excessive requirements bespeak Smith’s lack of understanding of how evolutionary biology is done. And that, I believe, comes from the fact that Smith is not a practicing scientist, but rather a philosopher, all of whose degrees were in philosophy. I usually don’t bring up credentials when discussing an argument, but I think her concentration on philosophy is relevant to her belief that evolutionary psychology fails to meet all tests of being a scientific field. Philosophers tend to be absolutists who require a ~~clam~~ claim to follow a set of strict rules.

Let me briefly say that I’m not a wholesale fan of evolutionary psychology, as a lot of it involves adaptive storytelling that is untestable. Often sample sizes are too small to be useful, and confirmation bias is strong. But that doesn’t apply to the whole discipline!

It is not ridiculous to think that, just as our bodies were shaped by natural selection acting on our ancestors, and that some of those ancient morphology persists (the shape of our spine, men being bigger and stronger than women on average, and so on), so our minds have been shaped by natural selection as well, and we still show traces of those evolved behaviors today. (Parental care is an obvious one, as is concern for one’s relatives, and so, I think, are the average differences in sexual behavior of men versus women).

Indeed, Smith seems to agree with me here. She doesn’t object to an evolutionary analysis of human mentation and behavior (“evolutionary psychology” in small letters), but to an extreme form of the discipline that she capitalizes as “Evolutionary Psychology.” The thing is, a lot of us don’t accept “Evolutionary Psychology”, at least as Smith construes it in her paper (my emphasis below):

If the arguments that I have presented in this article are sound, the methodological defects of Evolutionary Psychology are so profound as to be unrectifiable, and consequently Evolutionary Psychology is not possible. Evolutionary psychologists simply do not have the methodological resources to justify the claim that the psychological causes of contemporary behaviors are strong vertical homologs of the psychological causes of corresponding behaviors in the EEA. The result for evolutionary psychology (as contrasted with Evolutionary Psychology) is less clear. No one should contest that the human mind is a product of evolution, and evolution must therefore enter into an explanation of human psychology in some way.

Evolutionary Psychology rests on three pillars: the massive modularity hypothesis, the claim that modular structures evolved as adaptations to recurrent challenges in the EEA, and the tacit assumption that mental structures can be individuated and so license claims about strong vertical homologies. These three components, taken together, are inconsistent with the competing hypothesis that evolution fashioned the human mind as a domain-general or modestly modular learning system.

But if the human mind is a product of evolution, and that evolution impacts human psychology, then she’s already conceded that there’s a valid program of “evolutionary psychology.” What she objects to in the capitalized version are its contentions that “adaptive” modern human behaviors—things like sexual behavior, mate guarding, jealousy, male displays like courting danger and showing off—are represented as “modules” (separable neural networks coding for feelings and behaviors). She also objects to other issues, which I’ll get to presently.

Well, I don’t care much about “modules”; if behaviors are evolved, then there must be some neuronal network that facilitates their appearance. Frankly, I don’t know what a “module” is, but if Smith is right and evolution must explain some of our psychology, then those explanations involve evolution of our nervous system. Modules, in my view, don’t at all need to be separate neuronal “compartments”, for we have no idea of how the brain is structured to produce behaviors. Very different behaviors might involve some of the same neurons.

Smith also claims that evolutionary psychology is different from evolutionary morphology because behaviors, unlike bodies, are flexible, and can vary depending on the environment and other circumstances. But that, too, fails to negate the value of evolutionary psychology. The value of parental care as an evolved trait is not negated because some parents neglect or even kill their children. The evolved difference in male versus human sexual behavior is not negated by the presence of some people, like gays, who fail to conform. The goal of evolutionary psychology should explain general tendencies, not absolutes. This insistence on absolutism and dogmatic programs of proof derives, I think, from Smith’s training in philosophy.

Smith also insists that not only must our behaviors be adaptive now, but we must show that they were adaptive in our ancestors, which of course is impossible (as it is for all traits in all creatures!). Further, and this is her big issue, we must show that the “modules” that produced an adaptive behavior in our ancestors are genetically related to, and the ancestors of, the “modules” we use today when performing the related behavior. This insistence on showing exact evolutionary homology between a behavior and its “module” today and its ancestral “module” in the past is what Smith calls the “matching problem.”

That too is overly stringent: how could we possibly show that the exact neuronal pathways involved in, say, males being promiscuous, are the same as those in our hominin ancestors? Smith is asking too much here. What we can do is use comparative data (do other primates show similar differences in sexual behavior?) as well as concocting tests (e.g., do males who are less promiscuous have fewer offspring?), and, if our predictions and comparative analyses continue to support our hypothesis, then we get increasing confidence in it.

Smith uses the example of greater male than female sexual jealousy as her sole example of Evolutionary Psychology nonsense: males are (and should be) more sexually attentive and jealous of their female partners because they can’t be sure of the paternity of their offspring (females can cheat). In contrast, females are much more sure of the paternity of their offspring, and so shouldn’t worry as much if their partner copulates with another woman. This, too, can be tested: one test (suggested by Matthew Cobb) is to see if this phenomenon obtains in those societies in which people don’t connect sex with reproduction (there are difficulties with that test, of course). There are other tests of the adaptive value of sexual jealousy as well, including measuring reproduction and paternity. The point is that one can do tests that either strengthen or weaken one’s confidence in a hypothesis, and we don’t really need to figure out what is going on in our ancestors so long as the phenomenon there also seems adaptive. And we don’t need to know anything about ancestral versus current “brain modules”.

Evolutionary biology is not about finding absolute truth, but about inference to the best explanation, and that is what Smith fails to understand. I suppose Smith would consider all phylogenies (family trees of species) unreliable unless we have a complete fossil record of all the species involved, including the common ancestors!

Indeed, one example that Smith gives of a trait that to her seems truly evolved by natural selection in humans is the eye-blink reflex. But, as Edward Hagen shows in his critique below, she uses exactly the kind of inference which she says is subsumed in the unreliable methodology of evolutionary psychology: presumed stories about the adaptive value of that reflex, comparative studies of other species, and so on. I will leave you to read Hagen’s critique, which is polite but trenchant, in the pages of The Evolution Institute (click on screenshot below).

Why is a philosopher critiquing evolutionary psychology? While other philosophers, most notably Philip Kitcher, have written valuable critiques because they were concerned about the lax standards of the discipline, Smith has another reason as well. As you might suspect, it’s because she sees Evolutionary Psychology (capital letters) as somehow vindicating racism and sexism. We can’t have that, and so we must dispose of the discipline.

Of course “is”s don’t imply “ought”s, as I keep saying, and no finding of evolutionary psychology could ever tell us how to treat other people morally and legally. But Smith doesn’t seem to see it that way. Rather, she presents a caricature of evolutionary psychology that might have applied in the 19th and early 20th centuries, but doesn’t apply any longer. This is from her interview at Gizmodo (my emphasis):

The evolutionary psychologists I engage with are not silly people. They are thoughtful and philosophical about these matters. However, the attractiveness of evolutionary theory coupled with peoples’ ideological biases forces them to not be as careful as they might be otherwise. I think that the consequences for our world when we misappropriate evolutionary accounts are really serious. People are saying that people of color have smaller brains, which is not true, or that women aren’t as great as men, which is not true... I think we have a special responsibility, when we say evolution made us that way, to recognize that people will read “innate” or “hardwired” as synonymous with evolution. We should be especially careful to not be making claims like these, which can have consequences.

There you have it ladies and gentlemen, brothers and sisters, comrades—a strong objection to evolutionary psychology on the grounds that it facilitates racism and sexism. I don’t think that’s a reason for opposing a scientific discipline, but a reason for opposing the unjustified misuse of a scientific discipline. I, for one, would find it very odd if people like David Buss, Steve Pinker, Robert Trivers, or Randolph Nesse would sign on to the propositions that people of color have smaller brains and that “women aren’t as great as men.” Smith is faulting an entire discipline for the misuse of it by some people—a hundred years ago.

___________

Smith, S.E. 2020. Is Evolutionary Psychology Possible? Biol Theory 15, 39–49. https://doi.org/10.1007/s13752-019-00336-4

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Category: evolutionary psychology