In Full House: The Spread of Excellence from Plato to Darwin, Stephen Jay Gould debunks two popular myths. The first myth is that the extinction of .400 hitters in baseball (there hasn't been one since 1941) signifies a decline in overall hitting ability. The second myth is that a tendency toward progress is a natural, built-in feature of Evolution. At first, these two myths seem wholly unrelated, but Gould points out a common statistical fallacy as the reason for their popularity.
First baseball. We may have lost .400 hitters, but the real pattern is a shrinkage of variance, on both sides of the batting average spectrum, while mean batting average has remained a stable .260 throughout most of baseball's history. Over time, the sport has developed better training and better strategies (not to mention a better, because bigger, pool of potential players), and over time, these methods have spread to the masses; instead of only the very best taking advantage of them, even subpar players began to lift weights, or study pitchers' tendencies, or swing with an upward motion, or whatever. But since batting average is a relative stat, and since pitchers also have improved with time (new pitches, for example), mean batting average stayed the same. So a .260 average today is more impressive than .260 fifty years ago. Now, there is an upper limit to how good a human can be at hitting a baseball (a "right wall" of limitation if we were plotting different batting averages on a chart). As .260 becomes harder to achieve, it moves closer to the right wall, and there's less space between it and the limit of human ability. So .400 moves past the right wall to the realm of the superhuman, while .350, for example, nearly touches it, occupying basically the same space that .400 did in past generations.
Now Evolution. There is a "left wall" of minimal complexity for living things, where single-celled organisms reside, and where life began. From there, the only option was to move rightward toward greater complexity, giving us plants, fishes, humans, etc. But this only creates the illusion of progress as built in or automatic, when really it's random variation in the only direction available for natural selection to take it. Humans' relative dearth supports this, since bacteria are, and have always been, the modal form of life. If progress is built in to evolution, why do these simple microbes still predominate? This is really just intuitive, as he points out, since all adaptations are local, with no teleological trends guiding natural selection. For example, if elephants grow hair and eventually become woolly mammoths because their habitat got colder, they're only "better" than elephants for the here and now. If it gets hotter again, they'll lose their advantage. That's not overall progress, just local, temporary adaptation. If anything, there may be a natural trend toward lesser complexity, as many lineages evolve into parasites, anatomically simple but successful creatures. ("Evolution" seems to be a misnomer, and indeed Darwin preferred "descent with modification.")
Overall Gould explains things very clearly for lay people like me to understand, but the book gets very repetitive. It probably could be a third of the size (It's 225 pages). I think it would make a nice coffee-table book since you could open it up at random and read for a few minutes and gain something. I'll give it four stars out of, oh, I dunno, let's say six.
Saturday, January 10, 2009
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very sad
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ReplyDeleteget it out
ReplyDeletewhy are you so hard to understand
ReplyDeletewouldnt
ReplyDeletethis fool
ReplyDeletei know where you sleep
ReplyDeleteWow CP, 20 comments! Your huge!
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