Monday, January 12, 2009

Darwin's struggle

periplus: from Robert Hughes, The Fatal Shore. He likes throwing in these bits of arcana. He's discussing a painting, what else, of Joseph Banks by Benjamin West; around him are the trophies oh his periplus, collected from around the Pacific. It comes from the ancient Greek, and is a description, generally in writing, of a shoreline itinerary.

I've been reading, inter alia, the biographies of Wallace and of Darwin, switching from one to the other, like channel hopping, and both men are putting jottings in their journals, Darwin in the late 1830s and early 1840s, Wallace in the mid to late 1850s, tantalising themselves with clues to the great mystery of species variation and connection. 

Now I've read the Darwin book - The Kiwi's Egg. The title refers to the flightless bird whose egg is almost monstrous in proportion to its body, so that the gestation period is long and presumably arduous. It's a metaphor for Darwin's dangerous idea, natural selection. 

One of the most interesting chapters deals with the doldrum period of natural selection - essentially between the publication of The Origin and the rediscovery of Mendel's work. This was touched on too in one of Gould's essays in Eight Little Piggies. Scientists weren't too happy about the toughness of natural selection, its wastefulness and brutality, and some of them didn't want to relinquish the creator, who must be benevolent. Darwin's insistence that there was no deterministic or goal-oriented element in evolution was very much out of step with his time. All sorts of problems were raised - that the planet was too young to have allowed for all that slow evolution [Lord Kelvin's  point of attack, since refuted with the advent of radiometric/isochron dating], that blending inheritance [much touted at the time] would dilute the selected traits over time [since refuted by Mendelian genetics], that soft inheritance [neo-Lamarckism] was more prevalent than inheritance by natural selection, that orthogenesis [an evolutionary approach based on linearity but which could not reveal its mechanisms] was the thing, and so on. Yet the theory of evolution by natural selection has managed to emerge more or less triumphant. 

Interesting reflections on Darwin and Wallace. Darwin the procrastinator, nervous about the implications of his views, finally pushed into action by the emergence of Wallace’s work. Wallace the man in a hurry as he called himself, talking about his theory before he had well worked out the detailed mechanism. Imagine if their positions were reversed – if Wallace had been the older man, travelling on the Beagle, and Darwin the later impoverished Amazonian adventurer. Something like the theory of natural selection, perhaps under a different name, would have emerged as early as 1840, and Darwin would hardly be known at all. But such hypothetical reversals are of course impossible. 



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