an evolutionarily adaptive reproduction strategy

There were a lot a comments from my unintentionally heteronormative post along the lines of “There are lots of accepted uses of the word ‘sex,’ Emily, so don’t be linguistic fascist.” (No one was actually rude about it – I’m exaggerating for entertainment value. EDIT: Well, one person was rude.)

Now, given that I am aware that there are other usages (I could hardly fail to be aware of it, as a fluent English speaker), why would I insist in my class, on my blog, and indeed in life, on such an abstruse usage of the word sex as “an evolutionarily adaptive reproduction strategy involving the recombination of two individuals’ genes”? After all, hardly anyone means that when they, for example, say, “I had sex last night” or “What’s the sex of your baby?”

What on earth could I be thinking?


Sex – as I’ve defined it (see above) – is a terrible pain in the ass. First you (and by “you” I mean any sexually reproducing organism, from orchid to chimp) have to produce some gametes, which are only useful if you can find a conspecific to juxtapose THEIR gametes with yours (unless you’re, say, a Komodo dragon female and can, under duress, make like the Virgin Mary). Not so very difficult maybe if you’re something like a starfish, who free-spawns, just leaving your gametes in the water in the vicinity of some other ready and able starfish.

But suppose you’re a peafowl. Now sex has gotten VASTLY more complicated! You have to persuade an opposite-sex conspecific to put their gametes next to yours. If you’re a peahen, you have to try to pick the male most likely to provide the healthiest sperm, and if you’re a peacock you have to prove to the females that you have the healthiest sperm, which involves growing a tail that makes you a walking bullseye for predators. What the fuck. And then you have to have intercourse. And if you’re a peahen you have to gestate the egg, lay it, incubate it, and then raise the peachick to reproductive age. Criminey!! It’s complicated, time consuming, effortful, and all for what?

Yes, for what?

Sex has to have a REALLY BIG payoff to be evolutionarily adaptive, because it comes with all that cost. That payoff is: the genetic recombination of two individuals’ DNA. All the hardware and software that supports mate selection, mating, and (to a large extent) parenting evolved in support of SEX: the genetic recombination of two individuals.

So what’s the big deal about recombination?

Alfred Kinsey – don’t tell me you don’t know who Kinsey was, he was a Harvard-trained entomologist who took his passion for collecting populations and observing the infinite variety within a species and used it to change the world forever – was fascinated by individual variability. No two individuals in a species were alike – not gall wasps, not humans. No two alike.

No. Two. Alike.

THAT is sex.

I have a twin sister. And still: No. Two. Alike. Do you see the beauty?

The function of recombination is diversity. DIVERSITY!!! Diversity is the point and the purpose and the goal and the ultimate reason for the existence of sex! That’s why starfish and peafowl go through the rigmarole of sex: genetic diversity. No two alike.

You should already be going, “Holy shit!” right? This is the point where, when I talk about this in person, I start weeping at the sheer beauty of it. I’m not exaggerating.

But wait! There’s more!

Now you’re not a starfish and you’re not a peafowl: now you’re a bonobo, a land-dwelling ape that lives in matriarchal communities. And an amazing thing has happened. Hardly any of the sex you have is reproductive – the females are only fertile for tiny windows of time throughout the year – and yet they have sex ALL THE TIME.

Secondary selection pressure has had its wicked way with all that hardware and software that evolved in support of sex, giving rise to an ENTIRE CULTURE of sex. Sex now mediates social communication, it facilitates economic transactions, it diffuses conflict, it establishes and maintains power hierarchies.

(Sound like any other species you know?)

Sexual behavior became social because of the kinds of offspring sex generates. Asexual reproduction produces mini-me’s, not baby-us’s. Mini-me’s are pret-a-porter, the fast fashion of reproduction. Sex produces baby-us’s because it’s SEX: the genetic recombination of two individuals. And baby-us’s are bespoke, handcrafted; they need to grow and develop and be protected (unless you compensate for lack of parenting by having huge numbers of offspring, most of whom die; but then numbers is just another, less cuddly kind of protection).

Offspring developed needs so intense that the survival of an infant depended on the cooperation of more than one caregiving adult. And so you know what evolution did for some species – clever, brain-inverting evolution? Evolution saw that sexual motivation was hanging around in the central nervous system right in the vicinity of infant-caregiver bonding, and it said, “Right, I’ll have YOU.”

Yes, I’m saying that LOVE ITSELF is a direct product of sex. And by sex I mean, of course, the genetic recombination of two individuals’ DNA. I’m saying that sexuality became social, relational, because of the dependent nature of the offspring produced by sex.

Do you feel the magic? Doesn’t it make you quake with the profundity of LIFE? If it doesn’t… then God, Jed…

And now… dear heaven, this is the big one… imagine you’re a human. A human, with little narrow hips to walk upright, and a great big giant brain to think with, and therefore the most dangerous childbirth in the mammal family and infants of such utter dependency that they would just freeze to death if you put them on the ground overnight.

And so human sex became the MOST social, most adaptable, most varied system of any sexually reproducing species. (This is the point at which my students would chant back to me: PHENOTYPIC PLASTICITY.) Sex EXPLODED, a trait of such vast plasticity that only a fraction of its forms are immediately adaptive. It had to explode: sex is now a parenting behavior in a species where multiple caregivers are crucial to the success of offspring; it’s loving bond, an economic commodity, a communication strategy, an art form, as well as a font of genetic and behavioral diversity – and still the ONLY method we have for moving our genes into the next generation.

Roughly speaking, then, genetic recombination gave us diverse and dependent offspring, which gave us romantic love and every kink and pleasure imaginable. The giantness of our brains had a lot to do with it, but even those giant brains were a product of recombination.

Some of this is speculation and some of it is over-simplified, but it’s essentially the story of human sexuality.

And it all starts with a luscious, lazy, extravagantly precious egg and teams of sweating, panting sperm (in humans, anyway). From there, from that point in evolutionary time and space, come diversity, dependent offspring, and the social functions of sex.

And thus humans, as from a seed a flower (more sex), come with our ball gags, golden showers, foot fetishes, Catholic school girl fantasies, whips, cages, breath play, sensation play, group sex, monogamy, polygymy, polyandry, jealousy, gays and lesbians and bisexuals and asexuals and queer folks and folks who don’t claim any identity and transfolks, and LOVE ITSELF – and also assault, abuse, rape, pedophilia, and wide and daunting array of harmful uses to which we put sex, all the dazzling and heartbreaking variety we witness in humanity – vast, limitless. As Kinsey said, “The only unnatural sex act is one you can not perform.” Variety. No two alike.

And THAT, O best beloved, is what I mean by sex. It is – and let’s just breathe deeply into the wonder of it – the genetic recombination of two individuals’ DNA. Which results in glorious diversity and social functions of sex.

Holy. Fucking. Shit. Right?

So. In my view, the intercourse you had last night or the genitals on your new baby or whatever other use to which you put the word “sex” can only be a tepid and scrawny, compared to vast powerful richness, delicate and messy, sticky, unrepentant, like the very best of lovers, of the technical definition: the genetic recombination of two individuals’ DNA.

Does it sound like I’m taking a limited view of what sex is? Am I saying that sex is all about reproduction? Am I excluding anyone? Is there not plenty of room for psychological and social factors? Is there not plenty of room for language and culture?

Did I persuade anyone? Even one person? That yes, biology-as-launching-point is not only not oppressive but actually a gateway to the CELEBRATION of human diversity, loving relationships, and even, dare I say it, social justice?

I have at least the advantage that this post is so unavoidably long that almost no one will actually read the whole thing.

Well anyway, it’s Carl Sagan’s birthday: