Steven Pinker -- How the Mind Works - Hampshire High Italian ...

Revenge of the Nerds 163from one another. In particular, their beaks resembled different kinds ofpliers: heavy-duty lineman's pliers, high-leverage diagonal pliers, straightneedle-nose pliers, curved needle-nose pliers, and so on. Darwin eventuallyreasoned that one kind of bird was blown to the islands and then differentiatedinto the thirteen species because of the demands of differentways of life on different parts of the islands, such as stripping bark fromtrees to get at insects, probing cactus flowers, or cracking tough seeds.But he despaired of ever seeing natural selection happen in real time:"We see nothing of these slow changes in progress, until the hand oftime has marked the lapse of ages." The Grants painstakingly measuredthe size and toughness of the seeds in different parts of the Galapagos atdifferent times of the year, the length of the finches' beaks, the time theytook to crack the seeds, the numbers and ages of the finches in differentparts of the islands, and so on—every variable relevant to natural selection.Their measurements showed the beaks evolving to track changes inthe availability of different kinds of seeds, a frame-by-frame analysis ofthe movie that Darwin could only imagine. Selection in action is evenmore dramatic among faster-breeding organisms, as the world is discoveringto its peril in the case of pesticide-resistant insects, drug-resistantbacteria, and the AIDS virus in a single patient.And two of the prerequisites of natural selection—enough variationand enough time—are there for the having. Populations of naturally livingorganisms maintain an enormous reservoir of genetic variation thatcan serve as the raw material for natural selection. And life has had morethan three billion years to evolve on earth, complex life a billion years,according to a recent estimate. In The Ascent of Man, Jacob Bronowskiwrote:I remember as a young father tiptoeing to the cradle of my first daughterwhen she was four or five days old, and thinking, "These marvelous fingers,every joint so perfect, down to the fingernails. I could not havedesigned that detail in a million years." But of course it is exactly a millionyears that it took me, a million years that it took mankind ... toreach its present stage of evolution.Finally, two kinds of formal modeling have shown that natural selectioncan work. Mathematical proofs from population genetics show howgenes combining according to Gregor Mendel's laws can change in frequencyunder the pressure of selection. These changes can occurimpressively fast. If a mutant produces just 1 percent more offspring