May 09, 2007

I've Got Your Back, Chuck

On a scale of one to infinity, with one being the least startlingly idiotic Op Ed article ever written, I believe I am now capable of defining infinity.

From Human Evolution Has Stalled on
Cancer, heart disease, diabetes, and a whole host of other medical conditions too numerous to mention here were all once fatal to humans. Many are now treatable to the point that sufferers can extend their lives well beyond what would be their natural lifespan otherwise. In many cases, this allows people to survive long enough to reproduce, thereby passing on their inferior genes to a new generation… Medicine (and in particular, modern medicine) bypasses [evolution] and promotes the idea that each and every human life is of equal value, even though (from a strictly Darwinian viewpoint) this is palpably false.
From a strictly Darwinian viewpoint this is, in fact, palpably irrelevant. The theory of evolution makes no value judgements about individual human lives relative to one another except inasmuch as some contribute less to the reproductive pool than others. But that has nothing to do with how we treat the sick, elderly, or genetically unfortunate (Darwin, of course, didn't even know what a gene was).

In any case, the claim that modern medicine "bypasses" evolution is so irredeemably misguided that it has merit only for giving me an excuse to go off on one of my habitual rants about how much I hate people who talk about evolution without actually understanding it.

To wit, I hate people who talk about evolution without actually understanding it. This goes not just for the author of the above article, but for the numerous people who left comments "debunking" it by saying something along the lines of, "Human evolution hasn't stalled, it has just reached a higher level at which culture is more important than biology."

This is bull. Culture affects selection pressures indirectly by changing, one, the resources available to individuals and, two, the nature of the competition between those individuals. But natural selection is still, by definition, a biological process, and culture doesn't affect it in any more profound a way than, say, a tornado.

No, the real reason why the mostly anonymous columnist at Kuro5hin is wrong is that he/she conflates two very separate Darwinian concepts; diabetes is not a selection pressure, it's an individual trait. As such diabetes does not itself represent 'natural selection', it just provides something upon which natural selection can act. Now, if the Earth was conquered by evil alien overlords who enslaved humanity and forced us all to subsist on high fructose corn syrup, that would be a selection pressure that would affect diabetics disproportionately, and you can bet we would see some hot Darwin on Darwin action in the gene pool. It really has nothing to do with diabetes per se, though; our evil alien overlords might also insist on compulsory insulin injections, and then the rest of us would be pretty fucked.

The point is, you can't make a priori judgements using human values about what traits are good or bad from an evolutionary standpoint, because natural selection is not human and acts indiscriminately and pretty much at random on genetically diverse populations of individuals. The number of people who have cancer or diabetes is immaterial until a selection pressure that acts upon those traits comes into play.

Indeed, the increasing number of people who rely on modern medicine to survive is setting us up to see natural selection get majorly kickstarted if modern medicine ever falters. (One of the few ways in which we can actually study evolution over the infinitesimal period of our lifetimes is by looking at our immune systems: those of us alive today are demonstrably different from those who lived before, for example, the 1918 Flu Pandemic.)

Anyway, long story short: natural selection acts on genetic diversity, so the only way it could ever "stall" is if every single human on Earth was genetically identical. That will never happen. Ipso facto, buy a biology textbook and don't speak again until you've read it.


I'm off to Boston tomorrow morning, so you can expect CWG on Friday and, most likely, little else for the next week.

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