Tuesday, April 03, 2007

Cultural evolution causes biological evolution   posted by agnostic @ 4/03/2007 07:13:00 PM

Returning to a favorite theme here -- debunking the balderdash that recent human evolution is cultural rather than biological -- consider how simple technological changes can influence human biological evolution. Take musical instruments: in an environment with no musical instruments, and thus essentially no music, you'd never know who were the rockstars (if male) or the dancing queens (if female). With no way to detect these sexy phenotypes, natural selection could not change the frequencies of alleles that contributed to them. But once the presence of musical instruments becomes a predictable feature of the environment, suddenly there's a pressure to be a good performer, and so traits both physical (dexterity, agility) and psychological (extraversion, emotional volatility) will increase, at least up to a point where any further increase would be a bad bet for newcomers as they crowd an already saturated niche. It's hard to show off when everyone else shows off in the same way.

Now, we commonly urge youngsters to "find their niche," yet many people ignore the obvious corollary of this ecological phrase, namely that whatever cultural processes spawn new niches will also result in a change in frequency of alleles implicated in the traits needed to thrive therein. Unlike Darwin's finches, humans don't need to expand into an unsettled archipelago to undergo adaptive radiation -- we can stay fixed geographically but broaden the range of niches in our "social-cultural space."

At my personal blog, I sketched out a reason for why technological progress tends to be more bustling than progress in more abstract disciplines like geometry, where progress appears to stagnate for quite awhile until "the next big thing" comes along. Basically, the purer arts and sciences are the hobbies of weirdos, whereas technology is usually a matter of life and death: i.e., outperforming the technology of your adversaries. This literal arms race keeps the pace of technological progress much more frenzied than in other cultural areas. The key is that new shields, spears, guns, and ships don't affect the fitness of just soldiers, because most of this new stuff will be ripped off by others to innovate civilian life.

For instance, there would be no common cars if militaries had not pioneered the technology of interchangeable parts and mass assembly-line production for ships and firearms. Nor could their interiors and exteriors be held together were it not for the common use of steel, an alloy whose first modern production method -- the Bessemer Process -- resulted from its inventor's efforts to more efficiently produce firearms for the Crimean War, and whose Captain of Industry (Andrew Carnegie) made his fortune through contracts to build warships for the US Navy. And since the widespread availability of the automobile, many males have carved out a niche whose appeal to females centers around owning a car when other males don't (the guy in 10th grade with his own car) or using their car to signal machismo (drag racers). So, to paraphrase a related slogan on technological changes fueling biological changes: howitzers hatched heart-throbs in hot rods.

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