Following up from yesterday’s post about how knowledge about the biological basis for X doesn’t tell us whether X is to be valued or pathologized, I need to put a few more points (including some questions) on the table.

First, in the comments thread to the Feministing post that prompted my post, a common (and frustrating) misunderstanding of claims from evolutionary biology has reared its head:

I wouldn’t put the clitoris in the same catagory as the male nipple by any means. The clitoris is not a by-product, and by the way neither is sex. And “liking sex that does not result in reproduction” could be applied to heterosexuality as well. …

Why do most of you not assume that homosexuality is a product of evolution? A direct product (not a by-product) of being human? If it wasn’t a desirable trait in some way then it would have been eliminated through natural selection.

The position of the commenter seems to be full-on adaptationist: every heritable trait that’s in our gene pool is there because it was selected for (because it confered an advantage in terms of living long enough to pass on our genes) at some point in our evolutionary history. While some evolutionary biologists are (or have been) adaptationists, not all are.

I don’t know that there’s a necessary link between being an adaptationist and taking umbrage when some trait you really value is labeled an “evolutionary byproduct”. But there have been some fairly explosive reactions to claims that physiological phenomena like female orgasm are evolutionary byproducts — that they are not selected for. I’ve blogged about this before, as have others, but let’s get the goods from a biologist. This is PZ Myers writing about Elisabeth Lloyd’s book about attempts to give good evolutionary explanations for the female orgasm:

Right at the beginning, she lays out the prerequisites for demonstrating that a feature is an adaptation. It has to be shown to be the product of genetic variation, it must be shown to influence reproductive success, it needs to have a mechanism shown to work in nature, and it should be shown by experimental manipulation of the trait or environment to have an effect on reproduction (the last one can’t be done in humans, obviously). This is not controversial; these are the basics. Then through the middle of the book she goes through each published hypothesis for the origin of the female orgasm and assesses it against each of those criteria, and also examines each for internal consistency and conflicts with the physical evidence. This is all just plain good science.

Lloyd settles on Symon’s explanation, that female orgasm is a developmental byproduct of selection for male orgasm, as the best supported explanation. That word, “byproduct”, seems to be what is arousing most of the critics’ ire, with the implication that unless something is intrinsically advantageous to reproduction, it is less valuable. This is not about value judgements, however; Lloyd is not arguing that the virtue of orgasms lies in their ability to promote pregnancy in women (although that is exactly the idea the adaptive hypotheses for it are promoting)–she’s demonstrating that many androcentric assumptions about female orgasm, such as that it promotes pair-bonding with the male, or assists sperm to enter the reproductive tract, or encourages women to lie about in a puddle of semen, are just not credible or supported by any good evidence. She suggests that maybe she should change the label from “byproduct” to “fantastic bonus” to get around this naturalistic bias, but I don’t know that I agree. I suspect that a great many human features we like are byproducts (OK, “fantastic bonuses”), and people need to get used to that fact. That a specific feature has been the target of selection does not necessarily mean it is “better” in social terms.

(Bold emphasis added.)

Let’s say it together: Being a target of selection doesn’t make a feature something we should value; being an “evolutionary byproduct” doesn’t mean we shouldn’t value a feature. Biology gives us all kinds of neat knowledge about where things come from and how systems function, but it’s up to us to decide what we value. This means biological knowledge shouldn’t be blamed for our decisions about what to value, and it also means that biology can’t make life simple for us by telling us what to value. The heavy lifting here is on us.

Razib has an interesting post in which he ponders how genetic screenings might (or might not) play a role in parents’ individual choices. I find myself pretty torn about these issues. On the one hand, parents (and parents-to-be) are the ones who are actually going to have to raise the kids, and their judgments about what kind of challenges they are up to are important. On the other hand, their kids will be swimming in a gene pool made up of other kids whose parents who have made their individual choices — and certain choices that are good for an individual within the population may, if enough other people exercise the same decision, end up being bad for the population as a whole, and even for the next generation of individuals within that population.

Imagine, for example, a country that limits families to one child and that has a tradition of valuing sons much more than daughters. In such a country, it would not be surprising if parents used prenatal screening as a way to detect and selectively abort female fetuses. This could even represent a caring choice on the part of the parents — they wouldn’t want a daughter to have to suffer through the hell it is to be a woman in that society. But what happens when all the sons have grown up and start looking for wives? Oops.

Personally, I also worry about unforeseen consequences of our choices down the road. Perhaps I only want children with attached earlobes (because I find detached earlobes aesthetically displeasing) and use prenatal screening to achieve that goal. Maybe my beautiful attached-earlobe offspring start a trend in my region and soon all the other parents are ensuring that they only give birth to attached-earlobe progeny. This couldn’t possibly do any harm to the gene pool, could it?

Who knows? Maybe there are other important genes close to the earlobe allele, and possibly we end up with less variation in those genes which could eventually come back to bite us.

I should note as well that Ben at The World’s Fair has noted that the earlier discussion here was pretty disconnected from the history of scientific values and the history of attitudes toward sexuality. He links an interview he did with a historian and philosopher of sexuality, so hie yourself that way to get some historical context.

Finally, we come back to the big philosophical questions: Is more knowledge always better than less? And does knowledge impel acceptance or action?

I value knowledge, but not about everything. Case in point: I purposely avoided getting any knowledge about the sex of either of my offspring before they were born. Not only did it not seem especially relevant (OshKosh overalls and Onesies do the job no matter what the sex of your kid), but it seemed like it would give the illusion of predictability — like it would somehow tell us at least a smidgen about what we could expect from the child. I would rather not labor under such false impressions.

Of course, it’s nothing about our scientific knowledge that tells parents that girl babies are like this and boy babies are like that — it’s cultural assumptions that people are leaning on. But we live in a culture, so it’s hard not to do that. Separating what the science tells us from what we were inclined to believe beforehand is pretty difficult. (Also, most scientists go home at night to the culture the rest of us are living in.)

And that makes the non-scientist’s reaction to scientific knowledge about the biological basis for X interestingly different in different cases. While people engaged in the struggle for equal treatment hope that finding a biological basis for homosexuality will establish that it is natural, not a choice, and thus deserving of respect, others who see homosexuality as a problem may see research into the biology of homosexuality as the first step in finding a “cure”. The science seems like it could be used to support either of these goals. Similarly, research into (in utero) biological factors that might explain why more boys than girls score really high on mathematical aptitude tests could (but for some reason hardly ever does) prompt a movement to create prenatal conditions more conducive to producing female math geniuses, or it could (as it does more often) prompt people to decide it’s natural for boys to be better at math than girls. (Interestingly, all the environmental influences between birth and age 12, when the tests are taken, magically drop out of the discussion, but that’s another rant for another day.)

Maybe the real difficulty here is that biological systems (like human beings) are really complex, so any given finding is only going to give us a tiny piece of the puzzle. And, we already have some fairly strong opinions about human beings (having lived our whole lives as human beings). So it’s pretty hard to prevent an isolated scientific result about human traits and not bring all our cultural baggage into how we interpret it. We just have to remember that we, not the scientists (usually), are the ones schlepping in that baggage.