Estrus


 


I started thinking about as estrus as a good rhetorical argument against the 'homosexuality is unnatural' ploy. (Not much you can do about the 'It's Against God's Will!" line of attack.) It goes like this: If God meant sex to be purely and only for reproduction, there's this system in other animals that makes sure that sex only occurs when the female is ready for reproduction--in heat. If human sex is purely and only for reproduction, why did God leave that out of the human being, while using it in cats, dogs, horses, et. al.?

It's a reasonably clever piece of rhetoric, and one which most anti-gay bigots would not be prepared to deal with--but then I started wondering--why don't, in fact, human beings have an obvious estrous cycle? (For you see, one of The Gillis Principles of Wisdom is: when you ask a rhetorical question, turn around and ask it for real.Interesting things result.)

Instead of resorbing the endometrium after a non-fertile cycle, human females menstruate, sloughing it off as a discharge. We share this phenomenon with other (but not all) primates, most notably the rhesus monkey (the by-now-infamous macaca); beyond the primates, it's really scarce, mainly in bats and shrews (both of which have insanely high metabolic rates which (say I) might have something to do with it). And accompanying it is a constant receptivity for sex in both male and female.

Why do we have it? What advantage do we gain by it? In fact, is there any advantage? From what I gather (and I'm just an amateur outsider of the Scientific American/Science News sort), there's not much more than speculation. Some ideas (that menstruation has an immune advantage by the discharges) lead to some interesting ideas (that this is to help the females deal with multiple foreign encounters)--but are pooh-pooh'd by some on pretty good grounds--like the fact that the uterine walls are not biologically cleaner after a discharge. The best theory (IMO) seems to be a bit banal--that menstruation enables a thicker endometrium.

But constant receptivity? That's something else again.

Let me shift gears and mention one of those great little questions from the pages of Analog Science Fiction back in the John W. Campbell days. I don't remember the exact context, fact article, editorial, book review, or who was in volved (It may have been Lester Del Rey, but maybe not.) The question was "What animal would be to mammals as mammals were to reptiles?" It's possible to smack it down as illegitimate in any one of a number of ways--but what a great starting point for speculative fiction!

Well, I'm going to take it one step farther: "What organisms would be to animals as animals are to plants?" And believe it or not, I think I have an answer (of sorts).

The rise of animal life is not a very pretty thing: in fact, it's pretty damn unfair. You've got'cher plant life, sitting there nice and sessile, absorbing incoming energy and, by a bunch of ingenious physiochemical tricks, using it to grow and to store it in useful retrievable form. All well and good. But then along comes the animal, who's discovered that, rather than do all that work, it's a lot easier to just go over and take what others have done.
Nasty, but what are you gonna do?

This flexibility and opportunism not only required but permitted motion, and more elaborate manipulation of the environment. And so, instead of a simple energy budget, you started to get a complicated cycle of predator, prey, feeding and being fed, defense and attack. And ecological niches became more a matter of relative populations and dynamic changes rather than mere functions of heat, light and chemical abundance.

So what is to animals as animal is to plant? An organism that, rather than fit in snugly to an ecological niche , takes over other ecological niches on an opportunistic basis. In other words, us. Intelligent life. (You there in the back! Stop sniggering!)

It's been said by others that Intelligence spells the end of evolution. And it seems valid: we are going to be at a point within the next century or two of being able to write organisms (and ourselves) from scratch. (Let's leave aside the 'create life' issue and all that that involves--let's just talk about the ability to modify a pre-existing genome to give it whatever characteristics we require.) Right now, we're a long way from being able to do it well, and we've done a lot of stupid stuff--but there's nothing unreachable about getting a working knowledge of genetic engineering and ecological design.

Thus we have, ultimately, the triumph of complex, flexible, and opportunistic systems over well-optimized hard-wired systems. I see this over and over again in various parts of the world. I was surprised and delighted when it was uncovered that the human immune system did not function based on a pre-existing library of antibodies for antigens, but rather improvised its defenses based on macrophages, T-cells, cytokines and B-cells . It's a system with analytic capabilities built-in, and while far from perfect responds to more threats than a library of antibodies could. Likewise, with the certainty of a starry-eyed SF fan, I responded to the discovery of introns an exons in the human genome with the blessed certainty that those neutral, non-functional segments of our DNA were latent libraries, subroutines kept in reserve as situations would require it--and there are encouraging speculations that this may indeed be the case . And of course, as for the power of the generalized digital computer over hard-wired servomechanisms, I refer you to the hunk of semiconductors, LCDs and metal you're reading this on.

As for menstruation and the perpetual horniness of all mankind? This is what I think, and by the Power of Grayskull, what I say goes on this blog. What I see is a system where, rather than having a reproductive system that is hard-wire optimized for the ecological niche (whether subtrropical trees, or savannah, or wherever we came from) we have a situation where reproduction may be called on at any point on an oppportunistic basis. This works al the better since humans don't have litters, and so population increase must be done with more application--and population management is more easily effected.
It's true that animals with an estrous cycle, when transported (say) from the northern to the southern hemisphere, have their cycles shift, so that they once again find themselves giving birth in the spring even if the spring is in October. But this opportunistic reproduction allows an organism to go from an environment with no seasonal changes (like the tropics) to environments with severe seasonal changes and adapt within months rather than generations.

Did the menstrual cycle facilitate intelligence? Did intelligence choose for menstruation? I won't go that far. (You may, though, if you want to.) But for me, it fits in with a Big Tendency. that of flexibility, sophisticated control, and fewer hard-wired processes. And what the purpose of that is, well--that's even more fun to speculate irresponsibly about.

But there's one maliciously amusing corollary to all this: menstruation and the continuous excitation of humanity being something of an innovation, it certainly seems that there's a pressure, a biolical need perhaps, forthe government of an estrus cycle to, all other things being equal, regulate sex and reproduction.

What supplies that in menstruating humanity? Why, of course--religion.

It would certainly help explain that, while all the splendid spiritual teachers of the world talk about the purity of the spirit, the need for kindness and mercy in dealing with one's fellows, and the need for honesty and justice and reason--whenever it moves from them to the general raft of humanity it all turns out to be about the regulation of sex and reproduction. Why, after all, is that?

Religion as our estrus cycle. There's something in that that appeals to the worst in me.

Bwah (as they say) ha ha ha ha ha.

Posted: Friday - November 03, 2006 at 02:16 PM        

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