[nostromo]

Most animals don't survive past their reproductive years. Humans and some whales do, but that's it.

Some evolutionary biologists suggest that animals that share wisdom or share childbearing duties with their offspring evolved to survive past fertility because doing so increases the competitiveness of their shared genes.

[tjradcliffe]

Grandparents transmit culture to their grandchildren. This is a very good bet as to why humans live such absurdly long lives.

It might even be testable.

I often wonder if the Upper Paleolithic Revolution (https://en.wikipedia.org/wiki/Upper_Paleolithic_Revolution) could be correlated with genetic changes related to longevity. If the genes responsible for our double-lifetimes (we live about twice as long as you'd expect a mammal of our heart rate to survive) were small in number and had mutations that could be traced back to ~50 ky BP it would be strong evidence for this idea.

[darkmighty]

Also, we didn't have enough time to evolve greater lifespans and longer fertility spans, we've done so artificially much quicker than evolution can handle.

[TTPrograms]

Well arguably we haven't evolved to survive past reproductive years - life expectancy past 40 is only about 150 years old. That's much too short of a time for evolutionary effects to have an impact.

[nostromo]

You're misreading the statistics a bit. The biggest gains in life expectancy have been at birth. There have been old people for a lot longer than the last 150 years.

Even Aristotle knew about menopause. And Plato lived to be 80.

[darkmighty]

You have to remember a significant time in human evolutionary scale is probably something like 10k-100k years. Looking at wiki page for life expectacy at the Paleolithic [1] (even at 15 years) shows it lines right up with woman menopause.

[1] http://en.wikipedia.org/wiki/Life_expectancy

[FeeTinesAMady]

Life expectancy is a mean value, and it's skewed by people dying young. So the life expectancy at the Paleolithic doesn't mean that people didn't survive past menopause: it means that a lot of people died young.