Genetic differences probably account for part of the difference between people who age slowly and gracefully and others who grow old more rapidly and die younger. Given that the genes controlling old age have their onset long after people have stopped having children, how could evolution have any effect on such genes?
Generally speaking, genes affecting an individual only in old age will be favored by natural selection if they provide a net benefit to that individual’s relatives. Evolution will select against genes that place the relatives at a disadvantage.
What example(s) of things that an older individual may (or may not) do, or that happens to them, might be effected by genes?