I'm nerding out over this Sunday's NYT Magazine's cover article on non-human homosexual behavior, a charmingly cautious tiptoe through the minefield of mistakes we make when we think about the evolution of sex.
I talked with students about this article before I read it, which gave me some sense of the degree to which journalist Jon Mooallem succeeded in steering readers away from bombs. It's about a 70% success rate, I'd say, but that's pretty good compared to a lot of the crap you see in the media. NYT does a better job, generally, than any other mainstream medium, and I'm including The Guardian, to which I am addicted but which sadly trades precision for authorial voice.
Anyway, it's put me in the mood to give a brief account of some of the biggest mistakes we make when we think about the evolution of sex. There are more than this, but here are 5 Big Ones:
MISTAKE 1. The Adaptationist Bias. Not all traits are the product of selection pressure. Some of them are byproducts, some of them are accidents or leftovers. Insert Stephen Jay Gould and spandrels here. Evolution doesn't move us toward perfection, it just moves us away from failure. Why else would we have a blank spot in the middle of our field of vision or, as Dara O'Briain points out, why would we bite in the insides of our own mouths? Just because it exists doesn't mean it was selected for as adaptive; maybe (like the human lower back, so prone to failure) it just wasn't maladaptive enough to be worth the effort of selecting against.
MISTAKE 2. The Naturalistic Fallacy. Birds do it, bees, do it, even girls with PhDs do it... so fuckin' what? What's natural has no relationship to what's right, good, or moral. This fallacy gets a fair bit of play in the NYT Magazine article, I was pleased to see. After all, rape, infanticide, and polygyny are common in other species. Does that make them models of human behavior? I understand the impulse to breathe a sigh of relief when you learn that other animals have same sex pairings - phew! that shows it's not a choice in humans! Well, no, it doesn't show that. It happens that it's not a choice in humans (most of the time), but comparative biology will only tell us how sociosexual systems can evolve, not how ours did.
MISTAKE 3. Human sex is about making more babies. Having lots of babies is not the measure of human reproductive success. Remember, as recently as 100 years ago three quarters of children born in Europe died before the age of 5, so making babies is a terribly expensive and inefficient strategy for humans. Instead, number of offspring raised to reproductive age represents success; in a way, having grandbabies is the measure of success in a species like ours, with a long developmental period.
Human sex is occasionally for reproduction, but mostly it's for social stuff. Bonding, resource exchange, play, lots of things.
MISTAKE 4. Anthropomorphizing Desire. In humans, there is a whole stormy internal experience of what it is like to be gay. There's the self-realization, the jarring discord between who you are on the inside and what others believe about you, the terrifying step out into the sunlight of a newly claimed social identity, the heady rush of love as you meet someone who rings your bell but isn't who you mother told you they might be.
I'm not being an arrogant scientist when I say that none of that exists for virtually any other species on earth. The birds in same-sex pairings described in the article? They don't FEEL gay.
Urgh, this argument gets very technical and complicated very fast, and it's Easter and I'm full of lamb and beer and in no mood to think carefully and critically. So let's just leave it at that for now, eh? Maybe another time.
MISTAKE 5. "Scientists have a social agenda." Sometimes they do. Sometimes EVERYONE has an agenda. But mostly scientists genuinely just want to understand the thing they're studying, they want to learn more about how that thing works, and where it came from. Honestly. I've met several scientists in my travels and mostly they're just the nerdy, curious people whose tendency to be precise makes them unpopular at parties but great in a lab.
When scientists publish their results, it's the public and politicians and journalists who want to extrapolate and figure out "what that says about us." Nothing. Virtually all of science, including evolutionary biology on non-human animals, says nothing about us. See the fallacies described above.
That enough of that. Happy Easter everyone, everybody. Hope you all had tasty lamb as well, or the nearest culturally appropriate equivalent.