Saint Sava (saint_sava) wrote,
Saint Sava

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Boot to Darwin's head.

Somebody popped their head into my cube the other day and asked me about ICE a couple of days ago.
"Gimme a context," I replied.
"Huh ... wow, can't help you."

So I pulled up some recent genetics papers published on the topic of ICE, or interlocus contest evolution, and just the hundred or so pages that I've read of it turns everything I know about evolutionary genetics on its head. Basically, the idea is a radical departure from typical Darwinian evolution, where the good of the individual is the aim; the evidence is accumulating that the rise of the human species is the product of a "genetic war" within ourselves, where the chromosomes do what's best for the individual chromosomes; the most illustrative of the skirmishes in this war is the one between the X and the Y chromosomes.

And when the papers said "war" they wasn't kidding. In fact, take a gander at this excerpt from The Philosophical Transactions of the Royal Society on the topic:
The mammalian Y chromosome is thus likely to be engaged in a battle in which it is outgunned by its opponent. A logical consequence is that the Y should run away and hide...

Well, hell's bells. I turn by back on biochem for five years and look what happens. Anyway, the concept being posited here turns out to be far less crankish than I ever could have expected. ICE contains as one of its theories that the X chromosomes are interested in accrueing genes that best befit them, and that they Y chromosomes have their own self-interest in mind, and, what's more, they are constantly attempting to sabotage and subvert one another. The thinking, I presume, starts here: since the Y chromosome is never found in females, it has no disincentive from accruing genes which would express very bad traits in females (for instance, antlers in deer; females have more pressing uses for the calcium.) The X chromosome wants none of that, obviously, and X chromosomes that appear in the males tend to develop genes that counter the expression of the offending gene on the Y chromosome. It still sounds unreasonable, but let's think: if there are an equal number of men and women, then there are three times as many X chromosomes than there are Y chromosomes, and the remark from the Royal Society begins to make a lot of literal sense. Furthermore, it seems a valid basis for a genetic theory that would explain social aspects like homosexuality. Darwinian evolution affords the homosexuality no quarter; according to it, it should have been bred out of the gene pool long ago. ICE states that while the gene "responsible" for homosexuality (in men, specifically, in this case) is an evolutionary disadvantage, it must have some expression in when found in women that more than makes up for it and ensures the continued survival of the chromosome.

Secondarily, it also gives an explanation for why the Y chromosome, genetically, resembles downtown Beirut in the 1980's: any gene with any serious sense of survival has long since packed up and moved away due to the war against the X's. One author goes so far as to suggest that this genetic "arms race" is largely responsible for the meteoric rise of the human species by requiring an drastic increase in our social skills and brain capacities in order for us to adapt to the espionage/counter-espionage nature of the sex-linked traits caused by ICE. I'm still warming to a statement quite that grand.
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