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worth repeating |
| Linda Partridge, of University
College London, delivered the second lecture of this year’s
Evolutionary Biology Symposium. Some excerpts: “When we’re thinking about aging, we’re thinking about change over time; as the organism goes through its life cycle its individual characteristics change. You could try to think about aging as a normal process, like development, one with a genetic control that makes sure that the right things come in the right place at the right time. . . . “Is aging a programmed process, like development? I think the answer has to be no, for the very simple reason that no genes have evolved specifically to cause damage. Aging is an individually deleterious process. . . . “There have been various adaptive theories of aging, but I think they’ve all crashed and burned. Probably the most dramatic of those is the suggestion that aging has evolved to rid a species of worn-out individuals—but of course such individuals wouldn’t be present if there was no aging process, so the whole thing’s a circle. There have been various other theories—such as, aging has evolved to allow species to evolve faster, because it shortens the generation time by group selection. But of course group selection is a very weak evolutionary force compared with direct selection among individuals. “We do know that aging has evolved; it’s not just inevitable that individuals wear out. We also know that the rate of aging is very characteristically different between the different kinds of species, for reasons that don’t seem to be related at all to the impact of the damaging process.… So aging is important, but it’s important as a side effect.” |
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—Beth Roberts |