Comment on Does evolution select for mortality?

Sat, 23 Feb 2013 23:15:24 GMT

Aging clearly exists, and is (almost) universal. But the fact that organisms have a certain property is only weak evidence that property was selected for. As I commented here, the other possible explanations are that immortal varieties either never arise in the first place, and so can't be selected; or else are always linked to some tradeoff or disadvantage which is selected against. And both options seem quite plausible and I believe have been demonstrated in specific cases.

The mechanism discussed in the article is (from memory, having read about the linked article once) roughly as follows. A cell accumulates damage over time ('ages'). When it divides, it can split damage between both child cells, making them both somewhat younger. Or it can place most of the damaged organelles in one child cell, producing a young and an old cell. This is a tradeoff that (unsurprisingly) is resolved differently by different cells at different times.

But the fundamental idea is that aging is damage accumulating over time. That's what the quote about "a fundamental and inevitable property of cellular life" refers to. There isn't a gene or behavior 'for' aging, and therefore there isn't an available mutation that doesn't age because it doesn't have that gene, and so evolution can't select it.

Contrary to Lander's view that "evolution has installed many many mechanisms to ensure that organisms die and make room for the next generation".

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