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Well the issue is whether a gene survives. Sometimes the individual is a good proxy for this, sometimes the population. Sometimes you just gotta consider the dy
by hackinthebochs 10y ago
Well the issue is whether a gene survives. Sometimes the individual is a good proxy for this, sometimes the population. Sometimes you just gotta consider the dynamics of a gene in a sea of other genes.
In the case of a supposed aging gene, consider that genes themselves preferentially want to exist in more fit organisms. If a gene could somehow manage this (i.e. be embodied with more fit genes), it will itself spread. But this is exactly what an aging gene does! Consider how an advantageous gene spreads through a population. This spread is a function of the number of generations that have passed. So a gene that could speed up the passing of generations will increase its own likelihood of existing in more fit organisms (increasing its own fitness), as advantageous genes within the population spread faster and are more frequently "paired up" with the aging gene. But the subpopulation with the aging gene is more fit than the subpopulation without it since the time for advantageous genes to spread is decreased, and so the aging population overtakes its counterpart.
- possibilistic 10y agoI don't think this is correct. I've never heard of any evidence for pro-aging genes, but I have read molecular biology rebuttals against this theory (Stephen Jay Gould or perhaps textbook sources, though unfortunately I can't recall well enough to cite them). You don't need extra genes or information to prefer organisms that age out of reproductive fitness. If advanced age during reproduction confers lower fitness, then the offspring are automatically less fit. While you could argue that there would be a competition for resources amongst the young offspring, this isn't much different than other scenarios that produce less fit or disabled offspring.
- hackinthebochs 10y agoTrue, you don't need extra information to prefer organisms that age out of reproductive fitness, but you might need extra information to ensure a timely death. It remains to be seen whether aging is just due to entropy or that regenerative processes are programmed to stop after a certain amount of time. Programmed death confers very specific fitness advantage to one's offspring as you're no longer competing with them for resources. The sharing of genes within a population creates a nice analogy between the population and a single organism. Programmed death for members of an organism is a standard feature of evolution. It's not implausible that such a feature exists at the level of population as well.
- possibilistic 10y agoThis Wikipedia article has a review of several evolutionary aging theories: https://en.wikipedia.org/wiki/Evolution_of_ageing https://en.wikipedia.org/wiki/Evolution_of_ageing None of these has been proven or widely accepted, and the entire class of theories has many rebuttals. They are interesting to consider, though.