Category: evolutionary psychology

Steve Pinker on the evolutionary significance of music

August 14, 2014 • 11:56 am

Eloquent as usual, and speaking in perfect, publishable paragraphs, here’s The Pinkah on The Really Big Questions podcast, discussing the evolutionary significance of music. (The bit is about 9 minutes long.)

Pinker argues that in fact that music is not an evolutionary adaptation, but a spandrel: a pleasurable byproduct of some other adaptation. What’s the “enabling” adaptation? In Pinker’s view, it’s language, which makes possible the production of music. (Reading is another such spandrel, another byproduct of language that simply couldn’t have been the direct object of selection.) Music is simply lagniappe from language: “auditory cheesecake.” He and host Dean Olsher then discuss, without resolution, whether music is a kind of language, or even a thought process.

Pinker notes that his view of music as a spandrel actually angered some people. He had figured that after making the thesis in How the Mind Works (1997) that many human behaviors have evolutionary roots, his suggestion that music is one exception would show that he wasn’t a diehard adaptationist, and not an ideologue sworn to see everything as a product of natural selection. But, he says, some musicians and scholars thought that if music were the product of selection, it would somehow validate its existence.  Of course evolutionary roots don’t validate anything’s existence, since some human traits seen as bad (Pinker mentions genocide, itself a byproduct of xenophobia) were probably adaptive in our ancestors.

Click on the screenshot to go to the podcast:

 

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Are primates hard-wired to be scared of snakes?

October 29, 2013 • 9:39 am

Posting will be light today as there’s a Horseman afoot (see next post), but I wanted to call attention to a paper that’s of some interest. It can even be construed as a decent bit of research on (horrors!) evolutionary psychology.

The paper by, Quan van Le et al. in Proc. Nat. Acad. Sci. USA (reference and download below), suggest that selection has molded primate brains to render them particularly sensitive to snakes.  I won’t be able to do it justice in the time I have to write, but let’s have a look.

The authors implanted electrodes in individual neurons of brains of three macaque monkeys (Macaca fuscata) and then did recordings from the neurons as the monkeys were exposed to four sets of pictures: snakes, angry monkey faces, monkey hands, and other geometrical shapes, like circles. The monkeys had been trained to look at the screen, and were rewarded when they did.  The authors’ “Snake Detection Theory” (“SDT”; what a name!) led them to hypothesize that these neurons—in a region of the brain called the “medial and dorsolateral pulvinar”, a region unique in primates—would respond especially quickly to images of snakes.  The pulvinar has been shown to be involved in visual processing of information from the eyes, and, as the authors note, “fast processing of threatening images.”  This hypothesis is of course based on the supposition that primates have an innate fear of snakes (these monkeys were reared in captivity and never exposed to snakes), a fear bred into them by natural selection. Those monkeys who weren’t especially attentive to snakes, the SDT suggests, were those monkeys who didn’t leave descendants! That would lead to natural selection for more attentiveness, perhaps detectable by neuronal response.

What the authors found supports the SDT, but weakly.  Of the 91 neurons tested with all stimuli, 37 were more sensitive to snake images, 26 to angry-face images, 17 to hand images, and 11 to shape images. That is weakly significant (hash mark), but only if you use the p < 0.1 criterion that is used in psychology but not biology (we use p < 0.05, and physicists are far more stringent).  Here’s the figure from their paper showing that snake neurons are more numerous (A), have a higher magnitude of response than the other categories of neurons (B), and have a lower latency of response than other categories (C; i.e., they respond faster). The brackets show the groups compared, and an asterisk or hash sign over a bracket means the comparison is significant.

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As expected, then, “snake neurons” were more numerous and more sensitive to the relevant stimuli than neurons in the other three groups, and in second place was the number and response of “angry monkey face” neurons, which I suspected from the outset since monkeys are surely selected to be attentive to each other’s expressions.

There were other experiments as well, involving scrambling the images, and these supported the main result.  I won’t go into more detail except to say that these result are suggestive, although the higher probabilities involved in some comparisons, particularly those of “hand” versus “face” neurons, are a bit worrisome.  The authors conclude:

. . . since the origin of primates, snakes have been a universal threat; both primates and snakes that can kill them (i.e., constrictors and venomous snakes) have their greatest diversity in tropical ecosystems (1, 2, 40, 41). Our data provide unique neuronal evidence supporting the hypothesis that snakes provided a novel selective pressure that contributed to the evolution of the primate order by way of visual modification (2, 5). We urge neurophysiologists to engage in similar studies across a wide range of primate species and closely related mammals to further examine the phylogenetic fingerprint of fast snake detection.

Now there’s an easier way to see if primates are innately scared of snakes: just expose a bunch of naive primates to snakes versus other animals, or snake-toys versus other kinds of toys, and see if they show a fright reaction. The authors mention that this has been done: snakes are detected “visually more quickly than innocuous stimuli” in both humans and other primates. What the authors show here is, perhaps, the neurological basis for that difference.

As they say, this study needs fleshing out with more species, especially those species that have never encountered snakes during their evolution. Maybe mammals are attentive to long skinny things for other reasons. But it’s a start, and it’s the kind of evolutionary psychology that I consider pretty good. My last statement will, of course, immediately trigger a group of quibblers to find faults with this work.  But you have problems with the paper, take them up not with me but with David Hillis, who was the editor on this one—and a reader here!

One more thing: they need to do studies like this with spiders, too—at least judging by the reaction of our commenters this week!

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Van Le, Q., L. A. Isbell, J. Matsumoto, M. Nguyen, E. Hori, R. S. Maior, C. Tomaz, A. H. Tran, T. Ono, and H. Nishijo. 2013 Pulvinar neurons reveal neurobiological evidence of past selection for rapid detection of snakes.
Proceedings of the National Academy of Science, early edition: 10.1073/pnas.1312648110

Another lame attack on evolutionary psychology

September 1, 2013 • 6:46 am

Someone called my attention to a short post about evolutionary psychology at Pharyngula:

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Well, ignoring the obligatory and customary reference to “douchebags,” I was curious about the article that inspired this post. Clicking on the link, I found a piece at the science/tech site io9 called “The rise of the evolutionary psychology douchebag” by Annalee Newitz. 

Newitz happens to be the editor-in-chief of io9, so I guess she can write anything she wants. Unfortunately, she decided to take on evolutionary psychology.  That was a mistake. Her post is godawful: a combination of tarring evolutionary psychology with a few ad hominems that have nothing to do with the field as a whole, and then a poorly informed argument for the impossibility of studying the evolutionary roots of human behavior.

Let me first give a disclaimer. I’ve been a critic of evolutionary psychology, particularly some of its earliest excesses, and attracted some attention with my two published and highly critical reviews (one co-authored with Andrew Berry) of Palmer and Thornhill’s dubious theory that the human brain contains a “rape module” prompting males to rape isolated females.  That was a bad example of the genre, largely because their work was tendentious and because the authors twisted their statistics in an inappropriate way to support the supposed “adaptive” nature of rape.

But the field has moved on and improved, and has made some important advances. I’ve detailed some of these in a previous post, “Is evolutionary psychology worthless?“. These belie the claim that “The fundamental premise of evolutionary psychology is worthless.” As I’ve pointed out, that “fundamental premise” is only this: “the human brain, like the human body, still shows traces of its evolutionary ancestry.” Disputing that on principle is equivalent to disputing evolution as a whole, for it would be odd indeed if our behavior did not reflect at least some of the selective pressures that molded it during the 6 million years of hominin evolution preceding the rise of civilization. Evolutionary psychology shows enormous promise for helping understand where we came from.

That said, there is of course still a bad strain in the field, one mainly seized upon by the popular press, which loves stories about how this or that behavior reflects our ancient evolutionary history.  And some evolutionary psychologists, like Satoshi Kanazawa, have catered to this appetite, eroding their credibility in the process.  But dismissing an entire field because of a few miscreants is a serious mistake, for it waves away the possibility that we can really learn something about what evolutionary forces molded our behavior.  It’s like dismissing evolutionary morphology in humans because, after all, how could it be possible that modern bodies reflect ancient selection pressures? Remember, brains are part of our body.

Nevertheless, Newitz wants to brush aside the whole field as fatally flawed. Her reasons are fatuous:

1.  Two evolutionary psychologists committed fraud.  As she notes:

Evolutionary psychology has often been a field whose most prominent practitioners get embroiled in controversy — witness the 2010 case of Harvard professor Marc Hauser, whose graduate students came forward to say he’d been faking evidence for years. Then there was the case of Diederik Stapel, whose social psychology work shared a lot of territory with evopsych. He came forward in late 2011 to admit that most of his data was sheer invention.

I don’t know much about the story of Stapel, but I do know about the Hauser tale, and the fact is that he was caught by fellow evolutionary psychologists, who (like Frans de Waal) called him out for his misdeeds.

But this is just dumb, for scientists in many other fields have committed fraud as well. It’s like dismissing molecular biology because at least a dozen practitioners have committed fraud. Newitz is simply smearing a field for bad reasons—probably ideological ones.

2. One evolutionary psychologist made a stupid remark on Twitter.  That was Geoffrey Miller from the University of New Mexico, who made this misguided tweet that Newitz reproduces:

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Yep, that was stupid, and Miller was rightfully called out on it.  But what on earth does it have to do with evolutionary psychology? Nothing. Newitz is making a purely ad hominem argument here. If one stupid remark by a scientist is sufficient to denigrate a field, then the entirety of science should be discarded. Newitz also notes that Miller has published some other hypotheses that seem bizarre, and I’ll agree with her here: sometimes I think Miller speculates far beyond the bounds of data, as he did in his book The Mating Mind. But that doesn’t mean that human thoughts and behaviors weren’t molded in part by sexual selection. Lots of scientists toss out bizarre hypotheses (Bill Hamilton in evolutionary biology was one of these), but sometimes they turn out to be correct.

Regardless, it’s journalistically irresponsible to smear a field the way Newitz has done.  So let’s get to her only “substantive” argument against evolutionary psychology:

3. Humans evolve too fast to bear behavioral traces of ancient evolution. 

This is all part of [Miller’s] and many other evopsych researchers’ project to prove that humans haven’t changed much since we were roaming east Africa 100,000 years ago. Evolutionary biology researchers like Marlene Zuk have explored some the scientific problems with this idea. Most notably, humans have continued to evolve quite a lot over the past ten thousand years, and certainly over 100 thousand. Sure, our biology affects our behavior. But it’s unlikely that humans’ early evolution is deeply relevant to contemporary psychological questions about dating, or the willpower to complete a dissertation. Even Steven Pinker, one of evopsych’s biggest proponents, has said that humans continue to evolve and that our behavior is changing over time.

But the classic evopsych douchebag, like Miller, absolutely wants to believe that humans are still in thrall to the same psychological forces that shaped our behavior much earlier in Homo sapiens evolution.

This is not only disingenuous, but reflects Newitz’s ignorance of evolution.

First of all, no evolutionary psychologist claims that human behavior hasn’t evolved at all since we roamed the savannas.  Indeed, Pinker has pointed that out, and I can give my own examples.  Within the last 10,000 years, for example, pastoral populations—those that raise sheep, goats, or cows for milk—have evolved a tolerance for lactose, for animal milk provides a valuable source of nutrition.  They’ve achieved this by simply accruing mutations that keep the “lactase” enzyme turned on, an enzyme that is usually inactivated after humans finish weaning. Genetic analysis shows, too, that this inactivation occurred within the last 10,000 years. So if you consider “milk drinking as an adult” as a behavioral trait (which it is, militated by our physiological tolerance for milk), then yes, it’s evolved recently.  And surely other traits have, too.  But remember that lactose intolerance is a behavior that many humans frequently show, and one that is an evolutionary holdover from our past—a time when milk was available only to babies from their mother’s breasts, and when it was probably disadvantageous to produce an enzyme beyond the time when it was needed.  Anybody who is lactose intolerant and avoids milk, then, is showing a behavior that is an evolutionary holdover from our ancestors.

Our penchant for fats and sweets can be seen the same way. It’s certainly not good for us—at least those of us who live in carb- and fat-laden cultures—but we still crave that stuff. This is an evolutionary holdover from a time when fat and sugar were valuable resources. Contra Newitz, this behavior almost certainly does reflect the deep relevance of early evolution to contemporary behavior.

The fact is that we diverged from our common ancestor with chimps about 6,000,000 years ago, but “civilization” with its novel selective pressures has been around only 20,000 years.  That’s only 0.3% of the total time encompassed by our lineage.  If one estimates, say, 20 years per generation, that’s about 1000 generations of human evolution: an eyeblink compared to the three hundred thousand generations in which we experienced selection within small bands of hunters and gatherers. Do we really expect that one thousand generations will completely efface behaviors evolved during 99.7% of the duration of the hominin lineage?

One way to answer this question is to look at whether we retain morphological traits that are holdovers from our “early evolution.”  If that’s the case, then one can infer that we probably still show behavioral holdovers from our past as well. And the answer here is unequivocal.  Here are some morphological traits no longer seem adaptive but haven’t yet evolved away, or can’t because of evolutionary constraints.

  • wisdom teeth
  • bad backs
  • fetal yolk sacks (which are empty)
  • our tailbone
  • goosebumps (adaptive in our relatives for erecting hairs)
  • skin fold at the corner of our eye (remnant of nictitating membrane)

I could go on, but the point is that these morphological traits are not useful (some are positively harmful), but persist as evolutionary remnants.

Why shouldn’t behavior be the same? After all, evolved behaviors actually reflect evolved morphology: morphological and developmental patterns of our brain’s wiring. Here are a couple of behavioral traits that, I think, reflect our deep evolutionary past:

    • Higher variance in male than in female reproductive success due to differential behavior of the sexes
    • Weaning conflict between mothers and their infants
    • Preference for relatives over nonrelatives (kin selection), and xenophobia (useful for when we lived in small groups)
    • Fear of spiders and snakes

Some of these can in principle be tested: for example one could do studies to show whether the fear of spiders is innate or learned. And there are other tests as well, and also some evolutionary psychology theories that have been falsified.

It’s simply nonsense to dismiss the field on the grounds that there’s no way that human behavior could show traces of its deep evolutionary past. We already know that some behaviors apparently show such traces, and morphology certainly does.  Yes, it may often be hard, or even impossible, to show with great certainty that some of our behavior reflect ancient selection pressures. But are we really going to say that evolutionary psychology is bunk?

The real reason why people like Newitz and others (that includes P. Z., I think) dismiss evolutionary psychology in toto is because they find it ideologically unpalatable: they don’t like its supposed implications. They presume that evo-psych somehow validates misogyny or the marginalization of women and minorities. They will deny this to their dying breath, of course, and pretend that it’s purely a scientific issue, citing a few anecdotal studies that are indeed laughable.  But I think we know where these people are coming from. Evolutionary biology itself has been used to justify racism or the sterilization of supposedly “defective” humans, but we don’t dismiss evolutionary biology because of that. Likewise, we shouldn’t dismiss evolutionary psychology just because some cranks draw “oughts” from “is”s.

When you read a statement like this:

“Developmental plasticity is all. The fundamental premises of evo psych are false”,

then you know you are dealing with ideology rather than science. The fundamental premise of evolutionary psychology is simply that some modern human behaviors reflect an ancient evolutionary history.  It would be odd if that were completely false.  And developmental plasticity is not all. If that were the case, then why do we still have wisdom teeth and bad backs?

A defense of evolutionary psychology (mostly by Steve Pinker)

July 7, 2013 • 7:54 am

I’ve been known for a while as a critic of evolutionary psychology, particularly when it first began as “sociobiology” in the Seventies.  At that time there was a lot of unsupported speculation being bruited about as “science” (i.e., human males evolved to have “rape modules”, a view that I criticized strongly). But over the decades, evolutionary psychology has matured, and I now see it as a valuable way of studying the origins of human behavior. Not that it’s all perfect—the “pop” versions, such as those produced by Satoshi Kanazawa, seem pretty dire to me, debasing a field that’s striving for scientific rigor. But even Kanazawa has been rejected by serious evolutionary psychologists.

Sadly, some self-professed skeptics have decided to debunk the entire field of evo-psych, and for reasons that I see not as scientific, but as ideological and political. That is, like the opponents of sociobiology thirty years ago, these skeptics object to the discipline because they see it as both motivated by and justifying conservative political views like the marginalization of women.  Well, that may be the motivation of some people, but not, I think, of most well-known workers in evo psych, who are merely trying to study the evolutionary roots of human behavior.  It pains me that skeptics are so dogmatic, so ideological, in viewing (and rejecting wholesale) a legitimate scientific field.

Because of this ideologically-motivated critique, last December I published a defense of the field, “Is evolutionary psychology worthless?“, pointing out a dozen areas of evo-psych research—most of them not involving gender differences—that I saw as valuable, interesting, and productive.

Nevertheless, the dissing of evo-psych by skeptics continues.  The latest critique occurred at the Convergence 2013 conference on a panel described in a post by P. Z. Myers at Pharyngula:

First panel: Evolutionary Psychology, with Stephanie Zvan moderating, and Greg Laden (a biological anthropologist), me (neuroscience by training, evo devo by occupation), and Indre Viskontas (neuroscience) (and who I met for the first time, and who was on a panel at an SF con for the first time…she’s good). My main point: Developmental plasticity is all. The fundamental premises of evo psych are false.

This paragraph disturbed me for two reasons. First, the notion that “the fundamental premises of evo psych are false” seems deeply misguided. After all, those premises boil down to this statement: some behaviors of modern humans reflect their evolutionary history. That is palpably uncontroversial, since many of our behaviors are clearly a product of evolution, including eating, avoiding dangers, and the pursuit of sex.  And since our bodies reflect their evolutionary history, often in nonadaptive ways (e.g., wisdom teeth, bad backs, the coat of hair we produce as a transitory feature in fetuses), why not our brains, which are, after all, just bits of morphology whose structure affects our behaviors?

Second, “developmental plasticity” does not stand as a dichotomous alternative to “evolved features.” Our developmental plasticity is to a large extent the product of evolution: our ability to learn language, our tendency to defer to authorities when we’re children, our learned socialization—those are all features almost certainly instilled into our brains by natural selection as a way to promote behavioral flexibility in that most flexible of mammals.

I haven’t listened to the entire Convergence panel because the audio is apparently quite bad, but I was distressed by the comments P.Z. made in the ensuing discussion, in which he expands his reasons for rejecting evolutionary psychology.  I sent P.Z.’s post and comments to my friend Steve Pinker, whose books have engaged quite deeply with evolutionary psychology, to get his reaction.  Steve sent me an email with his responses, and then gave me permission to publish them.  (I add the caveat, at Steve’s request, that this was an informal email, and he’s not to be held responsible for slips of grammar or punctuation!)

I post P. Z.’s comments (with links) below in italics (and an “M”), and Steve’s responses in bold type (with a “P”)

A comment P. Z. made in the ensuing discussion:

M: Fundamental assumptions of evo psych: That you can infer an adaptive history from the distribution of current traits — that they are adaptations at all is an assumption usually not founded in evidence (this is not to deny that that there are features that are clearly the product of selection, but that you can’t pick an arbitrary attribute and draw elaborate scenarios for its origins). . . 

P: Of course “arbitrary” and “elaborate” are the straw-man giveaways here. What about carefully selected attributes, and minimal assumptions about phylogeny with a focus on function, as we do for other organs? You can ask what the spleen is for – and it would be perverse to do physiology without asking such a question – without “drawing elaborate scenarios for its origins.”

M:. . . That behavioral features that have been selected for in our history are represented by modular components in the brain – again with rare exceptions, you can’t simply assign a behavioral role to a specific spot in the brain, just as you can’t assign a behavior to a gene.

P: No one in Ev Psych points to specific spots in the brain – that’s cognitive neuroscience, not evolutionary psychology. The only assumption is that there are functional circuits, in the same way that a program can be fragmented across your hard drive.

M: . . . That the human brain is adapted to a particular environment, specifically the African savannah, and that we can ignore as negligible any evolutionary events in the last 10,000 years, that we can ignore the complexity of an environment most of the evo psych people have never seriously studied, and that that environment can dictate one narrow range of outcomes rather than permit millions of different possibilities.

P: The savannah is a red herring – that’s just a convenient dichotomization of the relevant continuum, which is evolutionary history. A minimal commitment to “pre-modern” gives you the same conclusions. By saying that the brain could not have been biologically adapted to stable government, police, literacy, medicine, science, reliable statistics, prevalence of high-calorie food, etc., you don’t need to go back to the savannah; you just need to say that these were all relevantly recent in most people’s evolutionary history. The savannah is just a synechdoche. 

M: I’d also add that most evo psych studies assume a one-to-one mapping of hypothetical genes to behaviors. . .

P:  Completely untrue – this was Gould’s claim in the 1970s, which confused a “gene for x” (indispensable in any evolutionary thinking, given segregation) in the sense of “increases the probability of X, averaging over environments and other genes” with “a gene for X” in the sense of “necessary and sufficient for X.” Every honest biologist invokes “gene for X” in the former sense; evolution would be impossible if there were no additive effects of genes. No one believes the latter – it’s pure straw.

M [continuation of previous sentence]:. . . and never actually look at genes and for that matter, ignore most human diversity to focus on a naive typological simplicity that allows them to use undergraduate psych majors at Western universities as proxies for all of humanity”

P: It’s psychologists, not evolutionary psychologists, who focus on Western undergrads –field research and citations of anthropology are vastly more common in ev psych than in non-ev-psych. PZ is engaging in prosecution here, not analysis – he’s clearly ignorant of the sociology of the fields.

As for diversity – is he arguing for genetic differences among human groups, a la Herrnstein & Murray?

P.Z. then made a second comment:

M: Developmental plasticity vitiates most of the claims of evo psych. Without denying that some behaviors certainly have a strong biological basis, the differences in human behaviors are more likely to be a product of plasticity than of genetic differences. . .

P: Plasticity is just learning at the neural level, and learning is not an alternative to innate motives and learning mechanisms. Plasticity became an all-purpose fudge factor in the 1990s (just like “epigenetics” is today). But the idea that the brain is a piece of plastic molded by the environment is bad neuroscience. I reviewed neural plasticity in the chapter “The Slate’s Last Stand” in The Blank Slate, with the help of many colleagues in neuroscience, and noted that the plasticity that allows feedback during development and learning during ontogeny is superimposed on an innate matrix of neural organization. For example if you silence *all* synaptic activity in the brain of a developing mouse with knock-outs, the brain is pretty much normal.

M: . . . I think good evo psych would focus on human universals (much more likely to be driven by genetic properties!) than all this stuff seeking justifications for cultural differences between the sexes or the races or arbitrary subgroups.

Steve didn’t respond to this last bit, but I did ask him to tell me what he thought were the greatest accomplishments of evolutionary psychology. This was in response to one remark (made, I think, by a panel member) that the discipline had produced no substantive accomplishments. Steve’s response:

P:  On accomplishments – there are vast numbers of topics in psychology that were barely studied before EP came along, and in which you just can’t formulate sensible hypotheses without giving some thought to function – they’d include sexuality, violence, religion, beauty, play, emotions, and parenting. Even other areas, like perception and memory, have always been evolutionary in the sense that researchers had a vague idea about “function” – the difference being that common-sense is enough when it comes to seeing in 3D, whereas you need to give some more thought to function in the case of, say, beauty.

For me there shouldn’t even be a field called “evolutionary psychology” for the same reason there shouldn’t be a field called “cognitive neuroscience” – you can’t understand any biological system without considering each of Tinbergen’s four levels of mechanism, development, adaptation, and phylogeny. “Ev psych” is simply the attempt to take adaptation/function seriously, just as “cog neuro” is the attempt to sharpen mechanism.

One gets two impressions when listening to the skeptics’ criticism of evolutionary psychology. First, they haven’t read widely in the discipline, and are criticizing either pop-culture versions of the field or a caricature (born of ignorance, possibly willful) of EP.  Even I know that EP advocates don’t often publish studies that rely solely on undergraduates.

Second, it’s pretty clear that the opposition to evolutionary psychology from these quarters is ideologically rather than scientifically motivated.  One gets the feeling that research on gender differences shouldn’t be done at all because it’s either designed to repress women, motivated by the desire to do that, or has the likely outcome of promoting discrimination.  Well, sexist scientists may try to do that, but I haven’t seen much of that since the Seventies.  And gender differences are fascinating.  There’s a reason, for instance, why human males are larger and hairier than females, and have more testosterone. Are we supposed to say “You can’t work on that—could have bad repercussions!” Sure, scientific results can always be misused, but I don’t see that as a reason to put up roadblocks against scientific research. After all, what field is more misused and misquoted than evolutionary biology? I am a frequent recipient of emails from Jews trying to convince me to reject evolution because Darwin ultimately caused the Holocaust.

And the differences in sexual behavior between males and females do parallel those seen in many animals.  Is that just cultural construction, or are there genes and selection pressures involved? One can surely study such things scientifically, just as one studies differences between the sexes of other mammals, without being committed to sexism. There are, after all, testable predictions involved.

No, the fundamental premise of evolutionary psychology is absolutely sound: our brains, like the rest of our bodies, are the product of evolution and natural selection over the past six million years, and some of our current behaviors reflect that evolution.  To deny that is ideologically motivated nonsense. To parse out the evolutionary component of such behaviors is the goal of evolutionary psychology.

 

A modest proposal: testing the Cinderella Effect

April 28, 2013 • 11:44 am

One of the most prominent results of evolutionary psychology research is “the Cinderella Effect,” made famous by the work of Margo Wilson and Martin Daly (you can find one of their summary papers here). Although I don’t pretend to be an expert on the extensive literature on this phenomenon, it’s pretty much what the name connotes: the more abusive treatment by parents (usually males) of stepchildren than of their genetically related offspring.  Studies have repeatedly shown that, when corrected for the proportion of stepparents among all parents, and step-children among children in a family, the step-children receive disproportionately more abuse than do genetically related children.

While these data have been disputed, I think the pattern has held up pretty well. (Anecdotally, I’ve seen this in my own family: my father’s mother died of Spanish influenza in 1918, a few months after he was born, and after his father remarried, they had another child. My father was severely mistreated compared to his half-brother. In fact, his childhood was made so unhappy by his stepmother’s abuse that he didn’t speak to his half-brother until he was about 60.)

To an evolutionary biologist, the Cinderella Effect has an obvious explanation: genetic relatedness.  If you marry someone who already has a child, and then produce your own child with him or her, that natural child shares half of your genes while your stepchild shares none.  Evolutionarily, it would pay you to funnel resources and solicitude toward your natural child and not the stepchild, because those resources will propagate the behavioral genes that promote such preferential care. In fact, adoption is rare among animals, probably for this very reason. Infanticide, too, has a similar explanation: when male lions take over a pride, they often kill all the cubs of the females, bringing the females back into estrus so they can produce the new males’ genetic offspring. It wouldn’t pay a male lion, evolutionarily, to take care of unrelated cubs—even though females do most of the hunting.

When I first heard about this, it made evolutionary sense to me, but I formulated an alternative hypothesis, not based on relatedness, that could explain the same thing. This hypothesis differs from the five “alternative hypotheses” described in the Wikipedia article for the Cinderella Effect.

Here’s my alternative, and I’m sure someone’s suggested it before.  It’s based on convenience rather than relatedness.  When one marries or mates with a previously-mated spouse, you may often do so because you love that man or woman rather than that person combined with their children.  That is, it’s possible that the children of the previous mate are regarded as encumbrances rather than part of the “love package.”  If you then have your own genetic children with that mate, they would represent a deliberate choice rather than an encumbrance.  Ergo, because you choose your own children but not your step-children, you may treat the latter abusively. (Note that this explanation still has an evolutionary basis—you have genetic children to pass on your own genes—but the differential treatment is based not on a “relatedness module” but on culture.

My alternative theory predicts results to those of the Cinderella Hypothesis. How, then, can one discriminate among them? What you need to do is find some items that are not children, but which you can choose to acquire with your new mate versus items he or she  acquired before they met you. This would separate genetic relatedness from the “acquisition” hypothesis.  What items could you use?

Pets!

If you marry someone who already has a pet, you might regard that pet as an encumbrance in the same way you’d regard a stepchild.  You didn’t choose the pet and you may not like it very much. In contrast, if you and your mate select a pet together, you’d be more inclined, under my hypothesis, to treat it better.  Ergo, the prediction of Coyne’s Encumbrance Theory is that step-pets will be mistreated or abused more than “own” pets.

Of course, there’s nothing that prevents my mechanism from operating in tandem with the genetically-based theory.

This is a bit tongue-in-cheek, but not completely.  And, as I said above, I’m not deeply acquainted with the Daly and Wilson theory—though I think it’s intriguing and possibly correct—so I may have overlooked someone who’s already suggested my hypothesis.

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Remember him?

Bonkers evolutionary psychologist explains why he’s not an atheist

January 15, 2013 • 6:50 am

If you’ve read anything about evolutionary psychology in the popular press, you’ll know about the infamous Satoshi Kanazawa. Although he’s a reader in Management at the London School of Economics, he’s published several books and a bunch of popular articles purporting to explain the evolutionary roots of human behavior.  I say “purporting” because he is probably the one person who’s given evolutionary psychology a bad name through his wild and unfounded speculation.  Among the claims that he has advanced (and which haven’t been supported by subsequent work) are that poor people in sub-Saharan Africa have more illness because they have lower IQs, that black women are rated as less attractive than women of other races because black women have higher levels of testosterone, supposedly reducing their physical attractiveness (see a critique here), and that we’re losing the war on terrorism “because our enemies have a full range of human emotions [including hatred] while we don’t.”

Kanazawa is a loose cannon, speculating freely—and invidiously—in the absence of data, and tarnishing the decent work that exists in evolutionary psychology. He instantiates everything I’ve criticized about the discipline, yet he’s been very successful.  Although he was fired from Psychology Today for the African-women speculations, he continues to get public audiences for his science-woo, and I understand that his books have sold well. The public, after all, does have an appetite for such speculation, for we want to understand our evolutionary roots—even if there’s no real data backing up the evo-psycho explanations.

That’s just a bit of background, for I want to highlight a new piece by Kanazawa at Big Think: “Why I am not an atheist.” After this piece, they should name the venue “Big Fail”, because there’s no thought on tap in Kanazawa’s rant.  It’s all based on the fact that Americans are nicer than other nationalities, that Americans are more religious than other nationalities, and therefore religion makes people nice.  It’s a correlation, of course, and hardly a causation, but even the primary data about “nice Americans” is totally unconvincing. It’s a piece as weakly supported as were Kanazawa’s speculations about human evolution.

But first, of course, he attacks the Antichrist—Richard Dawkins—on completely erroneous grounds:

Thanks to Richard Dawkins and his ilk, “atheist” now means someone who is (and acts as if he is) intellectually superior, and who mocks and derides the deeply held and personal religious beliefs of less intelligent others by pointing out how wrongheaded and stupid they are to believe what they believe.

Virtually all of Dawkins’s contemporary examples of how evil, oppressive and destructive religion is come from Islam.  There is no question that Islam is an evil, oppressive and destructive force, but that does not mean all religions are.  In fact, I would contend that, apart from Islam, most contemporary religions throughout the world today are for the most part forces of good most of the time.

Dawkins’s major problem is that he doesn’t know Americans and how religion works in the United States.

Each of Kanazawa’s assertions about Dawkins is dead wrong, and I hope I don’t have to tell readers why. But why does Dawkins”s supposed ignorance of America lead him to such an ill-founded atheism? Because of a). one study on civility in big cities, and b). Kanazawa’s personal experience with Americans, including The Argument from Television.

Americans are by far the most religious people in all of the western industrial world.  And anyone who has lived in and traveled to as many places as I have will unanimously tell you that Americans are the kindest and most generous people on earth.  Although it would be difficult to demonstrate it scientifically, there is absolutely no doubt in my mind that Americans are the kindest and most generous people on earth because they are deeply religious.

It is not just the opinions of those who have lived and traveled everywhere.  There are actual data.  In 2006 the Reader’s Digest conducted a worldwide survey of residents of 35 different countries throughout the world and reached the conclusion that New Yorkers were the most civil and courteous people in the world.  Late-night comedians mercilessly lampooned the finding, because everybody knows how nasty and mean New Yorkers are.  What they didn’t realize, however, is that the Reader’s Digest’s study was an international one, comparing residents of major cities throughout the world, and New York was the only American city chosen.  So their study didn’t show that New Yorkers were more civil and courteous than people in Charleston or Des Moines (they almost certainly aren’t); it showed instead that Americans – even the meanest and nastiest ones in New York – were more civil and courteous than Russians and Kiwis.

What the hell?  Does what holds in New York hold everywhere in America? (My own experience, by the way, is that Americans are really nice to foreign travellers, but not as nice to their fellow Americans. And that, as a traveller in foreign lands, I’ve experienced unremitting kindness as well.) Are the differences between cities statistically significant? What about those unsampled countries? Here’s a list of the countries studied, with their “courtesy indices”:

New York USA 80%
Zurich Switzerland 77
Toronto Canada 70
Berlin Germany 68
São Paulo Brazil 68
Zagreb Croatia 68
Auckland New Zealand 67
Warsaw Poland 67
Mexico City Mexico 65
Stockholm Sweden 63
Budapest Hungary 60
Madrid Spain 60
Prague Czech Republic 60
Vienna Austria 60
Buenos Aires Argentina 57
Johannesburg South Africa 57
Lisbon Portugal 57
London United Kingdom 57
Paris France 57
Amsterdam Netherlands 52
Helsinki Finland 48
Manila Philippines 48
Milan Italy 47
Sydney Australia 47
Bangkok Thailand 45
Hong Kong 45
Ljubljana Slovenia 45
Jakarta Indonesia 43
Taipei Taiwan 43
Moscow Russia 42
Singapore 42
Seoul South Korea 40
Kuala Lumpur Malaysia 37
Bucharest Romania 35
Mumbai India 32

Notice any countries missing? Where are the hyper-religious countries of the Middle East and sub-Saharan Africa?

Further, here’s the protocol, as reported by The Reader’s Digest (RD):

RD sent reporters to major cities in 35 countries where the magazine is published — from Auckland, New Zealand, to Zagreb, Croatia. In the United States, that meant targeting New York, where looking out for No. 1 — the heck with the other guy — has always been a basic survival skill.

The routine in New York was similar to the one followed elsewhere: Two reporters — one woman and one man — fanned out across the city, homing in on neighborhoods where street life and retail shops thrive. They performed three experiments: “door tests” (would anyone hold one open for them?); “document drops” (who would help them retrieve a pile of “accidentally” dropped papers?); and “service tests” (which salesclerks would thank them for a purchase?). For consistency, the New York tests were conducted at Starbucks coffee shops, by now almost as common in the Big Apple as streetlights. In all, 60 tests (20 of each type) were done.

Well that settles the issue! Nothing about how women are treated, nothing about freedom of speech, nothing about government enforcement of morality, corruption, and so on. The supposed effect of religion can be measured by the frequency of dropped papers and opened doors?

And of course, even if you could trust those pathetic data, and even if they did hold for all the nations of the world, with a statistically significant correlation, what does it say about causality? What if you substituted average income, or income inequality, for religiosity?

Kanazawa goes on to claim that a television program like “On the Road”—an American show that features ordinary people doing nice things for others—could never survive in Germany or the UK because they’d run out of nice people!

Kanazawa adduces other anecdotal evidence:

If you want to know how incredibly good and generous deeply religious people are, I’d recommend the 2007 documentary film For the Bible Tells Me So.  I wish I could be as good and kind a human being as many of the people who appear in For the Bible Tells Me So are, and I am deeply ashamed and saddened that I am not.  I am just as much of an asshole as Dawkins is.

Yes, that’s right: he calls Dawkins (and himself) “assholes” at The Big Think.

Kanazawa ends with a slur and a final unsupported assertion:

Dawkins tells religious people to their faces that their beliefs are delusional because God in fact does not exist.  It is a scientific fact that God does not exist, so it is not rational to believe in God.  I wonder if Dawkins walks up to random people on the streets of Oxford and tells them that he is more intelligent, better looking, and wealthier than they are.  That would also be scientifically true, but I would consider such behavior to be exceedingly gaudy and tasteless, as gaudy and tasteless as telling the same people that they are stupid to believe in God.

What a mischaracterization of Richard’s claims! Again, do I need to refute Kanazawa’s slurs?  And, after all this, Kanazawa claims that he’s more atheistic than Dawkins. Look at this mess:

It is ironic because, according to Dawkins himself, I am actually more atheist than he is in the original meaning of the word.  Fellow Big Think blogger Mark Cheney quotes Dawkins as saying “On a scale of seven, where one means I know he exists, and seven I know he doesn’t, I call myself a six.  That doesn’t mean I’m absolutely confident, that I absolutely know, because I don’t.”  It’s funny, because, unlike Dawkins, I absolutely know for sure that God doesn’t exist, as any scientist would.  For scientists, it’s very simple; absolutely nothing exists in the universe, except for those entities for which there is credible scientific evidence for their existence.  So I know for sure that God doesn’t exist for the same reason that I know Santa Claus or Superman doesn’t exist.

But I am not an atheist.

He’s not an atheist even though he is absolutely sure that God doesn’t exist? What is he, then? He quacks like a duck but calls himself a swan.

And “as any scientist would,” he absolutely knows for sure that God doesn’t exist? Well, I’m a scientist, and I don’t absolutely know anything for sure (except, perhaps, that I think). And what kind of statement is “absolutely nothing exists in the universe, except for those entities for which there is credible scientific evidence for their existence.” Has he contemplated the possibility that things may exist for which we don’t yet have credible scientific evidence? That was the case for the Higgs boson a year ago.

This whole piece is a mess, and it’s an embarrassment to whoever puts together The Big Think. Can anybody spout this kind of garbage at that place?

Is evolutionary psychology worthless?

December 10, 2012 • 6:47 am

There’s been a lot of kerfuffle on the intertubes about the value of evolutionary psychology, the field that studies the evolutionary roots of human thought, language, and behavior. I want to weigh in here with my answer to the question posed in the title, and my answer is, “Certainly not!”

Now I am known as a critic of evolutionary psychology, and I have been quite critical. For example, I’ve published two scathing critiques (one with Andrew Berry) of Randy Thornhill and Craig Palmer’s unfounded theories of the adaptive significance of rape (see references below). I have gone after the popular distortions of evolutionary psychology that appear in the press or books (e.g., my comments on David Brooks’s New Yorker article “Social animal”—an article subsequently turned into a dreadful book). And I have criticized some evolutionary psychologists for failing to police the speculative excesses of their colleagues.  But I’ve never maintained that the entire field is worthless, nor do I think that now. In fact, there’s some good stuff in it, and it’s getting better.

I have seen evolutionary psychology begin to mature with its criticisms and disclaimers of its more radical exponents (e.g., Satoshi Kanazawa), and its increasing concentration on evidence and testability rather than just storytelling.  Although I don’t keep up with it as much as I once did, I do teach some of it in my introductory evolution class.  I have to admit, though, that as the field has evolved, I’ve become less critical of it as a whole.  That is, I think, as it should be!

My position has always been that good evolutionary psychology should meet the evidentiary standards of papers on the evolutionary significance of behavior in other animals—standards that are, say, met by papers in the journal Animal Behaviour. Good evolutionary psychology should be able to make either predictions or what I call “retrodictions”—i.e., hypotheses that make sense of previously unexplained or puzzling data.  (Darwin made many “retrodictions” in The Origin.) Granted, we can’t go back to the African savanna and witness the evolutionary forces that produce a new trait (hell, we can’t even do that for most traits arising today!), but we can construct reasonable hypotheses about how our behaviors arose and then test them.  Or, if tests aren’t possible now, we can make intriguing suggestions that future researchers may find a way to test, as Einstein did with his theory of general relativity. That is not “storytelling,” but the limning of hypotheses that could lead to understanding. “Storytelling” is the endeavor that purports to explain something in a way that can’t be tested, or is satisfied to tell a story without finding ways to test it.

As for those writers who do a good job presenting evolutionary psychology in popular works, I’d suggest both Frans de Waal and Steve Pinker.  I know these men, and, believe me, they are no Kanzawas.

And as for academic, as opposed to popular, evolutionary psychology: before you dismiss it whole hog, do me the favor of reading this 2010 paper in American Psychologist by Jaime C. Confer et al. (download free at link; reference below). It’s an evenhanded exposition of the state of modern evolutionary psychology, how it works, what kinds of standards it uses, responses to some common criticisms (e.g., “we don’t know the genes involved”), and, for the critics, examples of  evo-psych hypotheses that have been falsified. (One example of a falsified theory is the old “kin selection” argument for the prevalence of homosexuality: the idea that homosexuals, though not reproducing themselves, stayed home and perpetuated their genes by taking care of their relatives.)

If you can read the Confer et al. paper and still dismiss the entire field as worthless, or as a mere attempt to justify scientists’ social prejudices, then I’d suggest your opinions are based more on ideology than judicious scientific inquiry.

Here are a few fields in which I think interesting and worthwhile evolutionary psychology is being done:

  • Incest avoidance, especially in those societies that haven’t made a connection between incest and birth defects.  Also, the proximate cues for avoiding incest, as in the failure of children raised in a kibbutz to marry.
  • Humans’ innate fear of harmful creatures or features, as in spiders and heights, and the lack of innate fears of more modern dangers.
  • The variance in offspring number between males and females in various societies, and the differential “pickiness” of males and females when choosing mates
  • The evolution of concealed ovulation in humans as opposed to other primates.
  • The use of odors and immune-system matching (i.e., MHC genes) as cues for mates.
  • The cause of sexual dimorphisms (e.g., size differences between males and females).
  • The cause of physical and physiological differences between human ethnic groups (was it sexual selection, drift, or something else?)
  • Gene-culture coevolution, as in the evolution of lactose tolerance.
  • The evolution or morality using comparative studies with other primates.
  • The evolution of language (see The Language Instinct by Pinker).
  • Parent-offspring conflict, and cases in which kin are favored over nonkin
  • Why we like food that is bad for us (e.g. fats and sweets), and why we feel disgust at certain foods or odors

Now in many of these areas we’ll never get definitive answers, but that’s characteristic of many areas of evolutionary biology, for ours is a historical science. Why, for instance, did feathers evolve on dinosaurs? Probably not for flight, for the evolution of feathers preceded that of flight, but they could they have arisen via sexual selection, species recognition, or insulation—or all of the above. We might be able to make observations that support some of these ideas more than others, but we’ll never have the absolute truth—only answers with greater or lesser probabilities. But science is not about absolute truth; it’s about the best possible explanation we can think of in light of existing evidence. And many areas of evolutionary psychology do support some explanations more strongly than others. Read the Confer et al. paper to learn more.

Anyway, those who dismiss evolutionary psychology on the grounds that it’s mere “storytelling” are not aware of how the field operates these days. And, if they are to be consistent, they must also dismiss any studies of the evolutionary basis of animal behavior. Yes, there’s some dirty bathwater in evolutionary psychology, but there’s also a baby in there!

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Confer, J. C., J. A. Easton, D. S. Fleischman, C. D. Goetz, D. M. G. Lewis, C. Perilloux, and D. M. Buss. 2010. Evolutionary psychology: controversies, questions, prospects, and limitations. American Psychologist 65:110-126.

Coyne, J. A. 2000. Of Vice and Men: The Fairy Tales of Evolutionary Psychology (Revew of A Natural History of Rape by R. Thornhill and C. T. Palmer). The New Republic 222(14):27-34.

Coyne, J., and A. Berry. 2000. Rape as an adaptation: a review of The Natural History of Rape, by Randy Thornhill and Craig T. Palmer. Nature 404:121-122.