Friday, February 21, 2014

A Justification for Diversity

OK, this is going to be a long one. That's what she said.

The other night I had one of the most stop-me-in-my-tracks stunning flashes of insight of my life. Now, it could be nothing. But just bear with me. When we reach the end together, you may not agree with me, or even know what the hell I'm talking about. But I promise, you will have been entertained. Because I will illustrate my points using only the choicest Anchorman animated gifs.

Like most liberals, I've long accepted the assertion that diversity is a Good Idea. Yet I've never kidded myself that I have a rational reason for this. Historically, monolithic cultures have met with some success. Ancient Rome sure made a big deal of it. I've never claimed my way is better for empirically demonstrable reasons. I've claimed my way is better because diversity makes me happy.

But now I have a quantifiable, rigorous reason to favor diversity. Or so it seems to me. Let me explain.

If you understand apostatic selection and polymorphic equilibrium, or if you just can't stand to listen to me expound on my half-baked understanding of population genetics, skip ahead.

Apostatic selection is frequency-dependent selection by predators. Simply put, predators prey disproportionately on the most common form of a prey species. For example, say you've got a species of beetle with two possible patterns: spotted or striped. The spotted and striped varieties are equally cryptic, i.e. neither is less conspicuous than the other. Now, say that 75% of this hypothetical population is spotted and 25% is striped. A predator species will eat about one striped beetle for every three spotted ones, right? Well, as it turns out, no. Spotted beetles will actually make up considerably more than 75% of the predator's diet. That's because birds, like humans, are good at pattern recognition. They develop what researchers call a "search pattern", the upshot of which is that searching for something improves their ability to see it. Because there are so many spotted beetles out there, the birds come to see them better than they see the striped ones.

Now, let's jump over to polymorphic equilibrium, a delightfully fun thing to say. Go ahead and say it out loud a few times. I do it every chance I get. "Polymorphic equilibrium, polymorphic equilibrium, polymorphic..." Ahem. Yes. Polymorphic equilibrium is stability in the relative proportions of different forms within a population over time. Take that same population of beetles as an example. The proportion of spotted to striped will remain conspicuously constant from year to year. In nature, we see this all the time. It's the number-one cause of divorce among population geneticists, who, upon witnessing such a phenomenon, start screaming the name of the Grant Review Committee Chair during sex.

Now here's the mind-blowing part--the part that's taken me years of reading research articles to get my head around. Predatory selection seems not only to maintain, but to create, polymorphisms in prey species.

To understand this, start by imagining a species of spider with only one form. It doesn't matter how inconspicuous that form is; the bird that eats it is going to get really good at seeing it. It's pretty darned easy to see how this constitutes an evolutionary pressure, yes? The bird will leverage its searching expertise, gobbling up those spiders least divergent from the phenotypic mean while failing to see the oddball mutants.

Fast forward a million years, or maybe only a thousand. I've heard lately that researchers are reexamining their ideas of how quickly evolution can act. Whatever. Fast forward however long it takes for an evolutionary shift to happen.

Now your spider comes in not one, but three, forms, also known as morphs. The first morph is a uniform and inconspicuous creamy light green color. The second has two red racing stripes running along its abdomen. The third has the same racing stripes, but the space between them is also red, so that most of the abdomen is covered in a red shield.

That's Enoplognatha ovata, a fascinating species of spider on which I've read tons of research articles. I have no proof that predatory selection got Enoplognatha to where it is. No one does. What we do have is some damned compelling research that demonstrates the evolution of polymorphic equilibrium in virtual prey. Researchers are quick to point out that this does not prove anything about evolution in natural systems, but boy is it intriguing. It lends credence to the idea of polymorphic equilibrium as a response to apostatic selection, and helps one visualize this intricate dance.

To see what I mean, imagine you're a bird, and you just can't get enough of the squirty, spidery taste of E. ovata. Roundabout June, the spiderlings are getting mature and active enough for you to notice them, and you start snapping them up. Every once in a great while, you might eat one with the brilliant red shield. That's the ovata morph, which usually composes between 1% and 10% of the population, but you don't know that. You don't understand population genetics; heck, you can't even see colors. The pattern is conspicuous, but you literally failed to see it because you were focused on its more common peers. The only reason you ate it at all is that you happened to see it move.

You end up eating the redimita morph--the ones with the red racing stripes--more often than ovata, because redimita composes around 30-40% of the population. But mostly you eat the lineata morph--those with no red at all--because they're so thick on the ground. Even though their unbroken creamy green color makes them inconspicuous in the foliage, an inconspicuous pattern is still a pattern, and you get hella good at finding it. The more you see it, the better you get at seeing it.

But there's a problem. As you and your bird buddies mow down the lineata morph, its proportion in the population drops. With each passing day, you have to work harder to find your preferred meal. You slow down and search more carefully. You start to notice more redimita individuals because now they compose more like 50% of the population. Eventually you're forced to abandon your strategy of looking for lineata, and shift your focus to redimita.

Days pass, and you feel pretty good about yourself because you've gotten just as good at finding redimita as you ever were at finding lineata. But you're bound to hit that same wall of scarcity you hit before, and since redimita composed less of the population to begin with, this time you hit it sooner. Again, the morph you've made such an effort to find gets scarce. Again, you're forced to restrategize.

Maybe you'll switch back to hunting lineata, or maybe you and your chums have already wiped out so many lineata and redimita individuals that you'll be forced to go hunting the rare ovata. It'll happen eventually, and when it does, good luck seeing a plain old lineata when you're going blind looking for that distinctive red shield on ovata.

You focused on the most common morph, but soon, by virtue of your focus, it no longer was the most common. So you shifted your focus, and that gave the first morph a breather. And so it goes. The more you specialize, the less effective your specialization becomes.

Note that this dynamic is self-stabilizing. Your own predation forces you continually to shift back and forth between search patterns, so the proportion of lineata to redimita to ovata levels off.

Note one other thing. Enoplognatha ovata has an inverse relationship between morph conspicuousness and morph frequency. In other words, The most flamboyant morph is the least common. This relationship is caused by a tri-allele dominance heirarchy in which the most dominant genotype corresponds to the most flamboyant and least common phenotype. Again, this is seen frequently in nature.

OK. Deep breath. Bring it on home.

Polymorphism arises in response to predation. Apostatic selection causes polymorphic equilibrium. Dominance hierarchies which produce an inverse relationship between morph conspicuousness and morph frequency further enhance the effectiveness of the polymorphism by pitting the predator's tendency to notice common patterns against its tendency to notice conspicuous patterns.

Or so says science.

Yes. As a matter of fact I do have a damned good excuse for taking you through all that.

So the other night, I'm walking from the living room to the kitchen and it hits me: "Homosexuals make up about 1.7% of the population. Extend that to people who identify as otherwise non-straight, and that number goes up to about 3.5%... 3.5%. Huh. 3.5%! That's in the same ballpark as the percentage of the ovata morph in a population of E. ovata..."

"...the most flamboyant morph is the least common..."

"Homosexuality is a morph!!!"

Yeah, I know. It's a stretch. But keep in mind that I'm not suggesting anything as simplistic as a tri-allele dominance hierarchy that yields heterosexuality, bisexuality and homosexuality. I'm not even suggesting that human sexual preferences, or any of the other traits I'm about to mention, are based on alleles at all. I find that question largely irrelevant.

What matters is that the polymorphic equilibrium model works. You've got a predominantly heterosexual population, so by definition heterosexuals are highly cryptic. You've got bisexuals, who blend into their surroundings with relative ease. And you've got homosexuals, who have the hardest time of all being inconspicuous.

"Aha!" you say. "If the population is in polymorphic equilibrium, then where's the predator?" Yeah, you're right. We're apex predators, so there is no literal predator working its apostatic voodoo on us. But look at human history. We were murdering the shit out of each other millennia before Quentin Tarantino made it cool. If humanity's self-destructive tendency ain't a predator, it'll do 'til somethin' better comes along.

So I say humanity's predator is humanity. Or, if you want to get more conceptual, humanity's predator is humanity's rich suite of self-destructive tendencies. After all, it kills off a hell of a lot of us, so why not call it a predator? Once you accept that notion, the polymorphism model becomes strikingly apt.

To see what I mean, just think of the sixteenth century. I'm sure you were thinking of the sixteenth century already, as any sensible person should. But just for the sake of argument, say you weren't already musing on the psychology of Elizabeth I, the confessional fervor that led to the formation of the Holy League, the near-impenetrable historiography surrounding the Battle of Lepanto, and the role of global socioeconomic factors in the Spanish Armada. It's crazy, I know, but there are people like that out there.

So say it's August of 1572, and you're a wealthy Protestant. You've traveled to Paris for the big wedding. You're having an awesome time... and then this happens. So sorry to hear about the savage beating, the slit throat and the defenestration. But perhaps your spirit can take some consolation from knowing that not only are there a lot fewer Protestants around to murder, but the remaining ones will blend in much better. So the Catholics will focus their energies on more noticeable targets for a while.

Sounds a bit like the birds and the spiders, doesn't it?

Now let's circle back to the Dada exhibition that is human sexuality. For whatever reason, we have a remarkable preoccupation with who is rubbing private parts against whom, and in particular with the disposition of semen. We're so preoccupied with this that we think straight-up murdering folks over it is a Good Idea. So on the morning after the St. Bartholomew's Day du jour, when there's no longer a ready supply of heretics, you know that sexual deviancy will be the next stop on the murder train.

As go the birds and the spiders, so go humanity and its human prey. Having eaten a lot of one morph, the predator must abandon its specialization and refocus on another. This continues until a stable point is reached in which the percentage of each morph in the population levels out, and the predator's tendency to specialize becomes useless.

And now we come to why I'm preoccupied not only with gay rights, but with larger considerations of human self-predation. I'm straight, so I don't have a lot to worry about when the predator comes looking for obvious sexual deviants. But I'm conspicuous in other historically dangerous ways. I don't believe in God--at least not in any conventional sense--and I think religion is, in its very best moments, a transparent if charming delusion.

But my current of oddity runs deeper and more subtle than simple agnosticism. I'm an odd duck. I choke on the zeitgeist. What my peers think so obviously right as not to be remarked upon, I think insane, and vice versa. I have a perniciously contrarian, countercultural streak running through me like a persimmon strand in a skein of brown yarn. I don't know if it's nature or nurture that put it there, but you can see it from a mile away.

Throughout the vast majority of human history, when that predator went hunting, it's people like me who stuck out like a sore thumb and got snapped up. I'm lucky to live in a place and time where weirdos are accepted, even celebrated. But that set of circumstances is an anomaly. It's still happening in a lot of the world today, and I have no reason to think it can't happen here again. There are plenty of folk tryin' to make it happen here as you read this.

I may not have a solid red shield on my opisthosoma, but I damn sure got the racing stripes. And I have no reason to believe the birds won't come 'round again. If Europe's old predatory ways reassert themselves on we bloody colonials, it's people like me who'll be the first against the wall. He said, as if one need range so far to find precedents for oppression, murder and genocide in the United States.

Go ahead. Say "opisthosoma". I swear to god, it will add a week to your life. Saying "posterior dorsal opisthosoma" adds a month.

Anyway. Human populations consistently exhibit a spectrum of more and less cryptic individuals. Much as religious conservatives would love to believe otherwise, homosexuals, atheists and a constellation of other outliers have existed in every human culture. We're not going anywhere.

Why is that? Given all the predation that's gone on over the millennia, you'd think the freaks would've been weeded out.

But maybe it's the intense weeding that's made the freaks so persistent, just like the birds' predation made those telltale red marks on the spiders so persistent. Having been preyed upon, our species evolved morphs that force the predator to shift back and forth between search strategies.

In other words, getting people riled up about the fags is easy, but once all the fags are dead or closeted, it takes time and energy to shift the bogeymantle onto the shoulders of the heretics and weirdos--two sets of which I have the dubious distinction of occupying the Venn intersection.

And that, folks, is why we need diversity. We can't allow the predator to get comfortable with one search pattern. After all, to do so would be to betray our heritage. We are the species-level response to predation.

We are fragile little spiders, and I have no illusions that the birds will ever stop coming. But we can own our red marks, and keep those buggers confused.

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