A few weeks back I read an... interesting homophobic set of screeds in a comment section.

[conuly]

(Oddly enough, reading comment sections can distract me when I'm feeling depressed, and I think we can all agree that I was feeling more or less depressed a few weeks ago.)

This poster was insistent that we shouldn't legalize gay marriage on evolutionary grounds. After all, gays can't reproduce, and that makes them an evolutionary dead end, and we shouldn't encourage evolutionary dead ends. There is so very much wrong with that "logic" that it's hard to see where to start untangling the knot, but what particularly irked me is that everybody who was trying failed to see that his central premise was wrong. (My pointing that out earned me the dubious distinction of being, as near as I can tell, the only person he didn't reply to.)

It seems counter-intuitive, but for a social species - and as a rule, humans are about as social as it gets - failing to reproduce can actually be part of an excellent reproductive strategy. Your mission, after all, is to see that your genes get passed on. That means you want your offspring and that of your siblings to have the best possible chance in life. And for some species, that means limiting competition and maximizing the adult to offspring ratio - which means that only one or two members of the group reproduce, and the others all join together to raise the young. The young get way more caregiver attention, they get more food (because they have more adults to provide it and also because Mom and Dad can get away while the other family members babysit), the death of the parents is not necessarily a death sentence for them (because they have lots of caregivers), and when they are grown they aren't competing with all their cousins for a bite to eat.

It's not the only successful reproductive strategy, but it's not that uncommon. I can think of several species that do that, starting with wolves and moving from there. (Okay, I know I've read of others, wolves are the only ones I can consistently name.)

Comments

[redbird]

In the extreme, that's the naked mole rat/bee/ant strategy of eusociality.

Looking at our closer kin, I think there's at least one species of baboon that routinely does the additional-carers thing. In most primate bands, essentially all the females are related, so taking care of any infant helps preserve one's own genes.

I assume the poster in question thinks adoption should be illegal as well?

[conuly]

1. I remember reading an article about baboons which pointed out that male baboons are extremely protective of the babies of their female friends, even if there is no way they could be the father of those babies. Of course, it's not clear how much baboons understand of how babies happen, but still.

2. I was not delving that deeply into his thought processes, such as they are.

[houseboatonstyx.livejournal.com]

There's a saying which I'm probably mis-remembering (since Google can't find many instances) as "The unit of survival is the tribe." No matter how many babies you produce, they need to be protected and educated -- which takes a village -- if they are to survive long enough to reproduce. And the whole village needs to survive for several generations, which takes divison of labor, some non-parents to take care of other things, etc.

[conuly]

Yes! That's why, we suspect, humans keep carrying on long after our reproductive years are over. Because human children survive better if they have grandparents. Most species aren't like that, they die not long after they stop producing babies (which makes evolutionary sense as well - if you're not making babies, your continued survival is taking resources from your descendants, so if you can't help boost the survival rate of your descendants you really ought to just go away), but humans are one of the exceptions to that rule. Humans and elephants definitely, and I think crows? Three highly social, extremely intelligent species, but I don't know enough about comparative grandparenting to say if that's all of them.

[redbird]

Humans and orcas are the only species known to go through menopause, a process that makes sense only because now-sterile people can contribute to the survival of their relatives.

[conuly]

I thought elephants did as well...? Well, I must have gotten confused there.

[redbird]

Or the article I read about orcas had it wrong, or I'm misremembering.

[conuly]

No, you're right, elephants don't seem to. But they do live long enough to help raise their grandchildren, and the presence of grand parental elephants is important for their social structure.

[houseboatonstyx.livejournal.com]

Grand parental elephants. What a lovely phrase. And lovely image. Dressed in ground-length robes, pacing in to straighten out a problem.

[silver-chipmunk.livejournal.com]

Communal insects of all sorts. Naked mole rats. And to a lesser extent meerkats. Those all come to my mind.

[conuly]

Meerkats, that's what I was thinking about. But I forgot about social insects and naked mole rats entirely!

[houseboatonstyx.livejournal.com]

Seems like it applies to many other species too. But (to be annoyingly fair) not usually by homosexuality.

[conuly]

Well, maybe. I've most definitely read something sciencey suggesting that homosexuality is in part evolution's way of knocking some people out of the breeding pool (or compensating them if they end up out of the breeding pool for other reasons), and other people were tackling the "oooh, natural law" component of his "argument" anyway. (Anything found in over 1000 species and counting is the very epitome of natural.)

I don't know if it's true that homosexuality is an evolutionary adaptation which functions in this way, just that I've read something about it maybe being the case.

[houseboatonstyx.livejournal.com]

Well, of course, people recognize homosexual behavior in animals more than they used to. But it would take a lot of observation to count how many individual animals who (how often?) indulged in it, actually had lower birthrates. (Ie, never had het sex, or were less fertile when they did.)

One key factor would be, not how many babies an individual animal sires, but how much of zis time zie spends on infant care (nursing, licking, fetching food for zis home-bound mate, etc) -- vs how much time zie has free for other community services (including instructing other animals' children).

I mean, bravo homosexuality! But among our kind of animals (wolves etc) , aren't there more common ways of having more aunts and uncles and fewer mommies and daddies?

[redbird]

Or it might be an example of what biologists call a spandrel: evolved as a side effect of something else, because they're somehow linked and there isn't sufficient evolutionary pressure against it.

A lot of people, and I would guess quite a few non-human animals, are more or less bisexual rather than exclusively homosexual, at least to the extent of being capable of functioning heterosexually. So we might both be willing/able to have children, and perhaps more willing to step out of the competition if this particular generation has a surplus of one gender. Even if the selection pressure is for bisexuality rather than homosexuality, you'd probably get both.