Thursday, August 1, 2013

Why we have pubic hair

A long piece in the New York Times on July 12, "Sex on Campus," by Kate Taylor, was food for thought for a number of reasons, not least because of what it tells us about the evolution of behavior. It's the tale of how, as the writer puts it, traditional sex in college has gone the way of the landline.  She interviewed a number of female students at Penn and she lets them tell much of the story themselves.  
One student says about a guy she hooks up with regularly:
“We don’t really like each other in person, sober,” she said, adding that “we literally can’t sit down and have coffee.”   
Ask her why she hasn’t had a relationship at Penn, and she won’t complain about the death of courtship or men who won’t commit. Instead, she’ll talk about “cost-benefit” analyses and the “low risk and low investment costs” of hooking up. 
“I positioned myself in college in such a way that I can’t have a meaningful romantic relationship, because I’m always busy and the people that I am interested in are always busy, too,” she said.
Until recently, it has been assumed that the "hookup culture", quick sexual encounters of whatever kind, was more satisfying to men than women.  That's because, as we all know, men want sex while women want romantic long-term relationships.  But Taylor's piece makes it clear that women are driving the current trends at least as much as men.  They talk about building their resumes and not having time for relationships.

Evolutionary psychology
The curious thing about this is how thoroughly it runs counter to what evolutionary psychology has been telling us for a long time.  Ev psych is a highly if not hyper-darwinian discipline that essentially tries to explain human behavior as the product of dictates of past natural selection that have now been built into our genomes.  For example, much of ev psych has accepted the premise that it's in females' generally, and hence human females' evolutionary interest to invest in men who will make good fathers for their children, while men never know for certain that a child is theirs and so aren't evolutionarily primed to invest in them or in relationships with their mothers.  Instead they want sex with as many women as possible, to proliferate their genes as widely as possible.  For excellent evolutionary reasons, the idea goes, men have spent eons developing strategies to avoid commitment, and women have spent the same amount of time trying to get them to commit, by hook or by crook.
Ev psych has churned out a multitude of theories explaining the evolutionary, adaptive basis for differences in mate choice, mate preferences, and the rates of promiscuity between the sexes. The latest amazing finding is that cunnilingus-assisted orgasm is a "sperm-retention strategy".  Will wonders never cease!

Further, the theory covers such deep theoretical questions as why we have pubic hair -- it's a sexual ornament that indicates sexual maturity and, thus, is attractive to the opposite sex.  But pubic hair itself has gone the way of the landline -- so much for sexual ornaments and indicators of sexual maturity.  It used to be that a woman's ankle could turn a man on, and that was before evolutionary psychology was even a gleam in anyone's eye, so why the field decided that what we find sexually attractive was fixed is anyone's guess.  As Taylor's piece makes abundantly clear, sexual morĂ©s are as changeable as the weather, and about as unpredictable!  It's not what we're attracted to that evolved, it's that we're attractable.

More generally, a proper critique of behavior genetics and evolutionary psychology recognizes that most of traits and behaviors they purport to explain long pre-date humans and so can't be analyzed in human-specific terms.  But more important is that if humans evolved to do anything it is to use cognition to evaluate circumstances and adjust their behavior accordingly, rather than to be hard-wired to do specific things.  What we're wired for is to have culture, but culture largely evolves on its own, not because of specific human genes.


Gaia's sister said...

Yes, but if you say this, the people in Evolutionary Psychology jump all over you, saying you are a cultural constructionist.

Personally, I think we should all be paying much more attention to the brain as a specialized organ to learn culture, and language. In fact we should be looking also into why we seem to have evolved a brain capable of learning many cultures and many languages.

Ken Weiss said...

Unfortunately, we face a conflict of ideologies in this area. It is partly due to social politics, partly due to the grip of Darwinian determinism, and partly due to the complexity of behavior. Clearly behavior evolved, or at least the ability to behave in various ways. That's an important subject, but is routinely oversimplified. The biggest problem,perhaps,is assuming that what we see in some study we do somewhere today represents what natural selection has specifically built into the genome. We have insufficient respect for the slowness and complexity of evolution and in humans perhaps, for the lack of precision when it comes to cognitive functions.

Joachim Dagg said...

"The latest amazing finding is that cunnilingus-assisted orgasm is a "sperm-retention strategy". Will wonders never cease!"

That was the hypothesis, Anne, but the finding was that this particular 'prediction 2' was not confirmed.

Jason Antrosio said...

Hi all, there has indeed been a lot of misunderstanding around issues of social construction and biology. I tried to tackle some of these in Anthropology, Sex, Gender, Sexuality: Gender is a Social Construction. Thanks!

Ken Weiss said...

Well, this is bad news indeed! Because now someone will have to get some grants to find out what cunnilingus _was_ selected for!

Of course, epistemologists will tell the authors that not confirming an hypothesis in some particular study (probably based on some sampling design and significance-value analysis of the data) is not definitive. For example, the sample may not be large enough, behavior recall not accurate enough, or this of that sort, which can lead to false claims of falsification.

But it's juicier, so to speak, to suggest that we need more research on this topic, because any behavior that's not neatly put into an adaptive pigeon-hole is a problem not yet brought to a satisfying climax.

Anne Buchanan said...

I apologize if I mischaracterized the results of the cunnilingus study, but whatever the results, it does illustrate a point, as does Gaia's Sister's comment: the assumptions we bring with us to our research questions frame the answers. Jason's excellent blog post discusses some of the issues.

When we ask why we have a brain that allows us to learn languages, or why we engage in cunnilingus, we're assuming that evolution built in a purpose. And indeed that our behaviors are genetically determined, which means that they evolved because our ancestors who engaged in them had more children. That's a fundamental, and indeed constraining -- and I would argue incorrect -- assumption. Instead, what evolved is our ability to imagine an infinite variety of behaviors, including inventing a huge variety of languages, cultures, sexual practices, and so forth. We needn't expect a purpose for each of them. Indeed, it's possible that cunnilingus is just fun.

Ken Weiss said...

I would put Anne's point a bit differently. Somehow, our brains are hard-wired, so to speak, to be able to process sensory input of all sorts, evaluate situations, and react accordingly.

We are programmed to 'want' to survive, eat, stay warm, reproduce, and so on. But our evolution led us to be able to imagine things as well as perceive them, to fill in the interstices between direct sensory input, etc. So we can deceive ourselves, and language or whatever has led to culture which is its own source of perceived reality.

As a result, the imputing of specific, much less genomic, effects of much of our behavior seems often very misguided. It's also rather clearly falsified by almost any standard.

There are clearly some specific, and some generic aspects of behavior that are genetically hard-wired. And working out what might reasonably be thought to be in that category is interesting and important. Further, much of that will have evolved eons before there were any humans, and hence don't need human-specific selective explanations.

But by far the most likely thing is that we are hard-wired not to be hard-wired. That is by far the most parsimonious explanation, as well.

Joachim Dagg said...

If I remember correctly, the idea that the female's orgasm is an adaptation for sucking the sperm up is old and found wanting a long time ago: It wasn't even EvoPsych back then. Now, as far as I understand, the study on cunnilingus is based on a false assumption. If the suck-up hypothesis is false in the first place, why test the cunnilingus hypothesis in the second?

Ken Weiss said...

Um, would it be going too far to say that it legitimizes lascivious 'research' that gets a lot of attention?

Would it be going too far to say that if you hold the ideological position (and that's a proper way to characterize it) that basically everything has to have a natural-selection-based adaptive explanation, then so does this behavior?

Would it be going to far to ask that the universality, frequency, and so on of some purportedly long-ago-selelcted adaptation, be ascertained, even just today? Is this a mandatory practice among the most isolated non-industrialized, non-state societies?


Jim Wood said...

Culture is language. Okay, that's an oversimplification, but I think it's almost undeniable that language (in the full human sense) is a precondition for culture (in the full human sense). Now language capacity is clearly biological: it's written into our brains, our vocal tracts, our hearing ability. In other words, it evolved. And it's plainly a complex adaptation, even if there's no single compelling theory about what it's adapted for. It also seems likely (to me) that full language capacity evolved soon after (or not long before) the appearance of anatomically modern humans. So it's old in terms of our species, and there is no shred of evidence that I'm aware of that it varies in any important way across human populations, except in the case of obvious genetic abnormalities. Language greatly facilitates social learning and thus accelerates the accumulation of cultural diversity. Some non-trivial part of this diversity is adaptive: Inuit cultures know how to hunt seals through ice, lowland South American cultures know how to detoxify bitter manioc. And they know these things in a way that is thoroughly non-genetic. The broader question (to which I think we don't know the answer) is whether cultural knowledge and behavior is, IN GENERAL, adaptive in a Darwinian sense. If it is, then it could be adaptive without being genomic (no?) and still require a "Darwinian" explanation. If it's not -- or at least some of it's not -- then Darwinian explanations would be, at best, only partly relevant to human cultural behavior. My guess as an anthropologist? Detoxifying bitter manioc is adaptive, but cunnilingus is "just" fun. (I also guess that those two topics have never before been brought together in a single sentence!) I would argue, as a general point, that we still don't know the extent to which culture can be subjected to adaptationist explanations.

Ken Weiss said...

I would only say that I don't think we should use the term 'Darwnian' here. Darwin's genius insight about how historical processes of change and differential proliferation, and descent with modification from common ancestors, is widely applicable.

But I think culture and other historical processes of that sort should be called 'evolutionary' but not 'Darwinian' because the latter involves the specific aspects of genes and their change and inheritance.

But, also speaking as an anthropologist--even as one with minimal fieldwork experience--I think that the gist of your message is right on the mark.

If one were to take the hyper-adaptationist side, one would ask who on earth would have ever thought of cunnilingus, much less tried it, etc? In other words (to take the question seriously) is there a genetic temptation to engage in that kind of recreation? Otherwise, why would we find it 'fun'? Wouldn't that be dangerous (an enemy could sneak up on us while we were so engaged, and chop our necessaries off). Wouldn't genes that led to it be removed from the population? Or would those who played that sport have happier mates and more offspring?

The real issue is, to me, to understand that a cognitive beast can do things that were not specifically programmed, don't reflect specific genetic variants, and are undetected by the 'forces' of natural selection.

Jim Wood said...

Ken, I accept your point about culture being evolutionary but not really Darwinian, even if most cultural evolutionists refer to themselves as Darwinists. Still, a lot of culturally transmitted behavior and knowledge IS clearly adaptive. (How much is " lot"? I don't know.) So how do we explain the process of cultural adaptation? My best guess, which sounds naive but I find pretty convincing, is that people aren't stupid: they tend to adopt culturally-transmitted things that clearly work or are at least associated with "success" (not necessarily reproductive success) among cultural exemplars -- in other words, what Boyd and Richerson call the "direct and indirect biases" in cultural transmission. Based on fieldwork in several different parts of the world, it seems obvious to me that people actually THINK before adopting new ideas and practices, at least new ideas and practices that potentially influence the material and social well-being of themselves and their families. Of course they also adopt things that aren't especially adaptive but that don't come at much of a cost either, such as (say) oral sex. Both fun and boredom are probably big drivers in cultural evolution!

Anne Buchanan said...

Jim, are you asking whether cultural knowledge and behavior, such as detoxifying bitter manioc, evolved by natural selection such that those who couldn't figure out how to do it starved? So, the adaptation would have left no genomic signature, but natural selection would have reinforced the behavior? If so, I'm thinking this would get tricky -- would the ability to do calculus be Darwinian because without it bridges would collapse? A matter of life and death?

Rather than figure out which traits are adaptive in a Darwinian sense and which ones not, it seems more parsimonious to me (whether that's a valid criterion or not) to consider the ability to adapt to be what evolved. But I'm going to have to think about this!

Ken Weiss said...

No argument with this. Darwinism is usually another word for precise pan-adaptationism, which I think even in the biological world is usually very inaccurate.

But there is no reason not to stick with a less loaded word, like 'evolution', without taking Darwin's name in vain. Darwin himself, as far as that goes, had a rather racist and very wrong-headed idea about human evolution and its relation to culture. So it's just, to me, a mis-use of the term.

As a person trained initially in cultural evolution (Leslie White et al.) who did not as I recall, use the word "Darwinian", I think we don't need to muddy the waters.

I feel the same about 'meme', a term the cultural Darwnists often use. I think it is a very mis-conceived equivalent to 'gene', again because it was hatched within a Darwinian gestalt.

But each of us certainly evaluates what we think would be adpative to our own lives (even celibacy, for priests, with heaven in mind). That is teleological, among other things, and the selection is by the agent (us) not by the environment, etc. These are contrary to 'Darwinian' evolution, I'd say, even if they are very important to how culture works.

Jim Wood said...

Anne, I'm not suggesting that specific bits of cultural knowledge and behavior evolve by natural selection. I'm not even saying that ALL cultural knowledge and behavior is adaptive in the biological sense. But I do think that most cultural knowledge and behaviors (if they're widely diffused) are unlikely to be terribly inconsistent with natural selection: they may or may not be beneficial, but they're unlikely to be very costly in fitness terms. It just so happens that my current research focuses on farming behavior and how it influences the risk of early childhood death (among other things). Now, early childhood mortality is potentially an important fitness component (although, as a demographer, I don't usually think of it in those terms). But I seriously doubt that genes are involved in, say, using an improved plow or a new landrace of rice. But do I think that people in traditional societies consider the implications for the survival of their children before they adopt a new plow or new crop variety? You bet I do. Does that make the whole process Darwinian? Beats me. Maybe that's just a matter of semantics.

Anne Buchanan said...

Got it. My preference is to say it's a matter of semantics because I agree with you, but would rather not imbue your view with such loaded terms.

Anne Buchanan said...

(I don't mean loaded in any bad sense, just pre-defined!)

Ken Weiss said...

I think you are using the term 'fitness' incorrectly in this context. At least, in Darwinian terms this has to be based on specific genetic variation to be relevant to biological natural selection.

Being relevant to cultural selection, or individual reproductive output is something different, and wholly important and relevant of course.

This (to me) illustrates the problem with terms like Darwinian and fitness in this type of discussion.

We can use words like 'evolution', or 'success' and the like, without confounding or mixing meanings.

That way, when an agricultural activity is really based on some genetic factor (in the human doing the activity) and it affects the actor's reproductive success, then it really is 'adaptive' and 'Darwinian'. Thus, keeping the terms to their (to me) proper meaning in this context, allows these nuances to be expressed more clearly.

Jim Wood said...

Ken, I agree totally about memes and the often silly analogies drawn between cultural and genetic evolution. But I also believe in cultural evolution and cultural adaptation, and I think it's profoundly important to understand them -- which I admit I don't. So, in my view, modeling cultural evolution is a fundamental goal, albeit one that we've not made much progress on as yet.

Ken Weiss said...

I could not agree with you more. Let me put my view differently: I think that in a kind of physics or 'real' science envy, too many are taking an easy route to explaining culture, by geneticizing it or Darwinizing it. That makes it molecular, objective, 'rigorous'.

Instead, I think (maybe because of the influence of White and others) that in essence culture proceeds as a higher-level phenomenon of its own or, to use a catchword that I don't really like to use, it's an 'emergent' phenomenon.

That there hasn't been much progress, yet culture is vastly more important than genetic variation to human beings and the biosphere, is a sign that we should be knuckling down to face up to the reasons we don't yet have a good theory, rather than fad-following and treating culture as if it were a branch of genetics.

I think the 19th and early 20th century (and maybe others before them) thinkers had many aspects of culture right. But obviously we don't yet have an adequate theory beyond very bland generalizations, if that.

Jim Wood said...

Gotcha, Ken. That's why I said that early childhood mortality is "potentially" an important component of fitness. Most of the time, I agree that it's not. And when it is it's often kind of trivial. Populations with high degrees of lactose intolerance don't drink much milk as adults. Duh...

Ken Weiss said...

Even the most abstract of such examples, like the stress-response genetic variants, are (if true) rather unspecific--such as what 'stress' means. We have malarial resistance but that hasn't stopped malaria or farming nor has it diminished the population anywhere.

Lactase, even if the story is true, is so very specific as to be a distraction from the larger problem.

One could rattle of many examples, I'm sure, of lactase-like adaptations, and there is no reason to be skeptical of them. Of course some dairying populations make yogurt and don't need a lactase adaptation so even there the cultural implication need not be specific.

Anyway, we don't disagree in any material way, I think. If you think of person-years' impact of cultural variation on peoples' lives, and compare that to the impact of genetic variation, the cultural importance dwarfs the genetic.

So why do we invest so highly in the latter, and why are the social sciences in such trouble? (that's a rhetorical question)

Joachim Dagg said...
This comment has been removed by the author.