3 ms·

Brenner touches in this in a recent paper: https://www.sciencedirect.com/science/article/pii/S0167494322002126?via%3Dihub https://www.sciencedirect.com/science

Brenner touches in this in a recent paper: https://www.sciencedirect.com/science/article/pii/S0167494322002126?via%3Dihub https://www.sciencedirect.com/science/article/pii/S016749432... > Second, animal gene sets evolved to allow individuals to acquire food, avoid predation, find mates and successfully reproduce. Long-lived species like humans also provide a substantial investment in caretaking of offspring until they can obtain food, avoid predation and reproduce for themselves. The advantages conferred to youth by parents mean that genetic selections for parental health are extant in caretaking species. Such genetic selections for post-reproductive health are not extant in non-caretaking species (Brenner, 2022a). ... > Think of it this way: if foxes can reproduce at 6 months, what genetic selections are present for them to live for six years? The ones that live for 6 years might reasonably produce 6 times as many offspring as those who perish in a year but those who die in a year would still contribute to the gene pool so long as they are successful at reproducing. Indeed, experiments done in flies that were selected for the ability to reproduce late in life suggest that hundreds or thousands of genes, not single dominantly acting genes, are modified to allow every organ system to function better over time in the resulting long-lived flies (Burke et al., 2010). However, animals in the wild are under little to no direct genetic selection for longevity beyond that to produce reproductive success. Personally, my guess is that long lifespans are a tradeoff with reproductive age fitness. Also, it seems there are diminishing returns for longer lifespans and the benefits of knowledge transfer from post-reproductive age individuals.

jordanozang 4y ago
Brenner claims "Animal gene sets have been subject to genetic selections for guile, strength and famine-resistance but have not been directly selected for longevity because". This is case 2 in my classification. He writes, "Indeed, experiments done in flies that were selected for the ability to reproduce late in life suggest that hundreds or thousands of genes, not single dominantly acting genes, are modified to allow every organ system to function better over time in the resulting long-lived flies (Burke et al., 2010)." The case of sirtuin genes, however, is disctintly different from this. The hypothesis there is that increased expression of sirtuins increases longevity. This is a change to the epigenome, not to the genetic content itself, which is what is what Brenner comments on. Also, what this says is not that "evolution never had any reason to favour another approach", but that evolution (at least in this controlled environment) was not able to stop aging. Perhaps you have other data to support that claim. Also, what this says is not that "evolution never had any reason to favour another approach", but that evolution (at least in this controlled environment) was not able to stop aging. Perhaps you have other data to support that claim. From the perspective of maximizing reproduction, maximizing fertile population is oviously ideal. Surely, if it's possible for a member of the species that is fertile to continue to reproduce and live longer, this would increase the species' overall reproductive capacity. Obviously, post-reproductive age individuals do not have this benefit. However, it doesn't seem improbable that loss of reproductive ability is caused by aging. I think that the tradeoff you mention between reproductive age fitness would make sense in the context of other adversity though. If survival in general is very difficult, surviving long enough to reproduce, reproducing as fast as possible, and being able to survive long enough to finish the process while it's placing various stressors on your body is desirable.

jordanozang 4y ago

Brenner claims "Animal gene sets have been subject to genetic selections for guile, strength and famine-resistance but have not been directly selected for longevity because". This is case 2 in my classification. He writes, "Indeed, experiments done in flies that were selected for the ability to reproduce late in life suggest that hundreds or thousands of genes, not single dominantly acting genes, are modified to allow every organ system to function better over time in the resulting long-lived flies (Burke et al., 2010)." The case of sirtuin genes, however, is disctintly different from this. The hypothesis there is that increased expression of sirtuins increases longevity. This is a change to the epigenome, not to the genetic content itself, which is what is what Brenner comments on. Also, what this says is not that "evolution never had any reason to favour another approach", but that evolution (at least in this controlled environment) was not able to stop aging. Perhaps you have other data to support that claim. Also, what this says is not that "evolution never had any reason to favour another approach", but that evolution (at least in this controlled environment) was not able to stop aging. Perhaps you have other data to support that claim. From the perspective of maximizing reproduction, maximizing fertile population is oviously ideal. Surely, if it's possible for a member of the species that is fertile to continue to reproduce and live longer, this would increase the species' overall reproductive capacity. Obviously, post-reproductive age individuals do not have this benefit. However, it doesn't seem improbable that loss of reproductive ability is caused by aging. I think that the tradeoff you mention between reproductive age fitness would make sense in the context of other adversity though. If survival in general is very difficult, surviving long enough to reproduce, reproducing as fast as possible, and being able to survive long enough to finish the process while it's placing various stressors on your body is desirable.