Just like reptiles, who die from the accumulation of damage, at a time depending on the rate of damage, but their point is that mammals don't merely die from accumulation of damage but also have a built-in clock.
replyWhy assume there is a clock, rather than assume the damage is at the metabolic level? None of the predominant forms of human chronic disease that lead to most instances of death today (artherosclerosis, cancer, neurodegenerative disease, metabolic dysfunction like diabetes) seem like an intentional function. They seem like unintended consequences of other functions, like lipid transport or DNA replication, that don’t get selected against because they fall beyond the natural reproductive lifespan of most people. I suppose you could say that the biological clock in question is the number of eggs a woman has, but a simpler explanation for limitation could be that eggs are just very energetically expensive to produce.
replyCorrect me if I'm mistaken, I was under the impression a human female is born with all the egg she will ever have, so the expensive production bit you're talking about happens during gestation of the human embryo.
replyYes. Although, technically, no. In humans there is a massive change as the result of the first time air touches the lungs. It inflates the lungs. It causes the baby's immune system to engage, disconnect and start working.
replyAnd it causes the ovi to start the cell division that will create the next generation, form the "yellow body" and then effectively disconnect from the baby girl's body (obviously that cell division doesn't complete until a sperm combines with an ovi, hopefully multiple decades later)
So normally, this happens immediately after birth, together with dozens of other big changes.
Because you can reset the clock, and even sabotage it. In fact, that's how we produce a certain class of medicine (by now probably 10 classes of medicine, but ...)
replyAlso, there Henrietta Lacks, died in 1951 of metastasized adenocarcinoma, but "still alive":
Is it really "wear and tear?" or is it an evolved mechanism to keep genetic drift and natural selection alive? Alternatively, it could be an evolved mechanism to avoid genetic bottlenecks caused by highly reproductive individuals over long periods of time.
replyIf John and Mary were first, how long until everyone is a descendent of john and Mary?
Just like an old chat. Start fresh without so much accumulated contextual baggage.
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