Longevity Traced to Grandmothers
http://www.voanews.com/content/grandmothers-longevity-24oct12/1532183.html
I talked a bit before about group evolution and that post-child-bearing adults are valuable to families. The grandmother hypothesis is a variation on the same theme. Looking over the wiki page it seems to me that a particular bias (or blind spot) is visible on the reported research. Researchers are using today’s reports of menopause and grandmother effects (of course, that is pretty much all they have) as opposed to what was highly likely to be extant during the period where this sort of behavior would have had an evolutionary effect. Given that other primates do not appear to have the same sort of longevity that humans do, it is hard to develop a conclusion that our longevity was just a quirk that is unique to our genes and not some product of evolution. It might be that the initial changes that lead to our (relative) longevity was indeed random (well, duh!, that is indeed the case for all mutations) but if it didn’t have a strong survival characteristic it wouldn’t have become or remained dominant. As such, I firmly believe (but doubt that, absent a time machine, that any of this could be proven) that the advent of dramatically reduced child bearing by older adults (in my mind, that would be in their 30’s; back then as it is quite likely that child bearing started as young as 9-10 years of age and likely women would remain constantly pregnant for the better part of the next two decades) made the group much more likely to do well because it freed up experienced people to focus on teaching and child care as opposed to a likely somewhat desperate effort to keep fed and to feed children.
Of course, theories without evidence are just nice stories and I can’t see how we could get evidence for something like this, so perhaps stories is all we will ever have.
