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

Revenge of the Nerds 171no bugs outside in cold months; winter is the best insecticide.) Perhapsthe incipient wings of insects first evolved as adjustable solar panels,which soak up the sun's energy when it is colder out and dissipate heatwhen it's warmer. Using thermodynamic and aerodynamic analyses,Kingsolver and Koehl showed that proto-wings too small for flight areeffective heat exchangers. The larger they grow, the more effective theybecome at heat regulation, though they reach a point of diminishingreturns. That point is in the range of sizes in which the panels couldserve as effective wings. Beyond that point, they become more and moreuseful for flying as they grow larger and larger, up to their present size.Natural selection could have pushed for bigger wings throughout therange from no wings to current wings, with a gradual change of functionin the middle sizes.So how did the work get garbled into the preposterous story that oneday an ancient insect took off by flapping unmodified solar panels andthe rest of them have been doing it ever since? Partly it is a misunderstandingof a term introduced by Gould, exaptation, which refers to theadaptation of an old organ to a new function (Darwin's "pre-adaptation")or the adaptation of a non-organ (bits of bone or tissue) to an organ witha function. Many readers have interpreted it as a new theory of evolutionthat has replaced adaptation and natural selection. It's not. Once again,complex design is the reason. Occasionally a machine designed for acomplicated, improbable task can be pressed into service to do somethingsimpler. A book of cartoons called 101 Uses for a Dead Computershowed PCs being used as a paperweight, an aquarium, a boat anchor,and so on. The humor comes from the relegation of sophisticated technologyto a humble function that cruder devices can fulfill. But there willnever be a book of cartoons called 101 Uses for a Dead Paperweight showingone being used as a computer. And so it is with exaptation in the livingworld. On engineering grounds, the odds are against an organdesigned for one purpose being usable out of the box for some other purpose,unless the new purpose is quite simple. (And even then the nervoussystem of the animal must often be adapted for it to find and keepthe new use.) If the new function is at all difficult to accomplish, naturalselection must have revamped and retrofitted the part considerably as itdid to give modern insects their wings. A housefly dodging a crazedhuman can decelerate from rapid flight, hover, turn in its own length, flyupside down, loop, roll, and land on the ceiling, all in less than a second.As an article entitled "The Mechanical Design of Insect Wings" notes,