Survival of the prettiest

For readers, Charles Darwin, born in 1809, apparently never gets old. Books by Darwin number 25. Books about Darwin, according to the global library catalog WorldCat, number about 7,500, with production ever rising. This cascade started with 22 books about Darwin published in 1860, the year after his On the Origin of Species appeared, averaged about 30 a year for almost a century, ballooned to almost 50 a year after World War II, and reached 100-plus in the 1980s. Currently we get about 160 a year — a Darwin tome every 2.3 days.

Even with a book population so large, most years bring notable additions, and so it is in 2017. This year’s offerings include a friendly takeover attempt in the biologist J Scott Turner’s Purpose and Desire (HarperOne, $27.99), which argues that today’s mechanistic neo-Darwinism needs to find room for the “agency” — the desire — that Turner insists drives every organism and, by extension, evolution itself. I’m not buying, but it’s a good read and a strong pitch.

Books closer to Darwin’s work also abound. James Costa’s entertaining Darwin’s Backyard (Norton, $27.95), for instance, draws on the often untidy experiments Darwin carried out at Down House (bees and barnacles, potatoes and pigeons) to show how he built his theory of natural selection — and to suggest DIY home experiments for the reader; a messy win. Further afield, the geologist Matthew J James’s Collecting Evolution (Oxford University Press, $34.95) recounts a 1905-6 Galapagos visit in which the legendary field naturalist Rollo Beck, wielding shotgun, burlap bags and camera, made observations that provided crucial support for Darwin’s work in those islands.

And further afield still, Rob Wesson’s Darwin’s First Theory (Pegasus Books, $29.95) dares, thank goodness, to work some of the rare Darwinian territory that is actually underexplored. Tracing the young Darwin’s tracks on the 1831-36 Beagle circumnavigation, Wesson relates how Darwin hatched his first, favourite, and most overlooked substantive theory, on the origins of coral reefs. In both method and vision — imagining forms changing slowly over time in response to changing conditions — this precocious, even audacious idea anticipated and possibly inspired the theory of evolution Darwin would publish two decades later.

But it’s another of Darwin’s theories, his least appreciated (at least to judge by popular books), that is his most seditious — and that this year finally gets the thorough defense it deserves.

A little over a decade after he published On the Origin of Species, in which he described his theory of natural selection shaped by “survival of the fittest,” Darwin published another troublesome treatise — The Descent of Man, and Selection in Relationship to Sex. This expanded on an idea he mentioned only briefly in “Origin.” Sometimes, he proposed, in organisms that reproduce by having sex, a different kind of selection occurs: Animals choose mates that are not the fittest candidates available, but the most attractive or alluring. Sometimes, in other words, aesthetics rule.

Darwin conceived this idea largely because he found natural selection could not account for the ornaments seen in many animals, especially males, all over the world — the bright buttocks and faces of many monkeys and apes; the white legs and backside of the Banteng bull, in Malaysia; the elaborate feathers and mating dances of countless birds including bee-eaters and bell-birds, nightjars, hummingbirds and herons, gaudy birds of paradise and lurid pheasants, and the peacock, that showboat, whose extravagant tail seems a survival hindrance but so pleases females that well-fanned cocks regularly win their favour. Only a consistent preference for such ornament — in many species, a “choice exerted by the female” — could select for such decoration. This sexual selection, as Darwin called it, this taste for beauty rather than brawn, constituted an evolutionary mechanism separate, independent, and sometimes contrary to natural selection.

To Darwin’s dismay, many biologists rejected this theory. For one thing, Darwin’s elevation of sexual selection threatened the idea of natural selection as the one true and almighty force shaping life — a creative force powerful and concentrated enough to displace that of God. And some felt Darwin’s sexual selection gave too much power to all those females exerting choices based on beauty. As the zoologist St George Jackson Mivart complained in an influential early review of “Descent,” “the instability of vicious feminine caprice” was too soft and slippery a force to drive something as important as evolution.

Darwin’s sexual selection theory thus failed to win the sort of victory that his theory of natural selection did. Ever since, the adaptationist, “fitness first” view of sexual selection as a subset of natural selection has dominated, driving the interpretation of most significant traits. Fancy feathers or (in humans) symmetrical faces have been cast not as instruments of sexual selection, but as “honest signals” of some greater underlying fitness. 
 

© The New York Times