So, this morning I was actually reading a cellulose-based carbon-marked news document (otherwise known as the Washington Post) as I performed my morning constitutional and found this really interesting article in the Health and Science section (this is the on-line link, I trust the content is identical):
Evolution has given humans a huge advantage over most other animals: middle age
http://www.washingtonpost.com/national/health-science/evolution-has-given-humans-a-huge-advantage-over-most-other-animals-middle-age/2012/03/12/gIQAtVnccS_story.html
It is a long article by web standards and I know some of my reader(s) won’t take the time to read it, so I will summarize:
The idea that life used to be (nasty, brutish and) short is based on life expectancies _from birth_. If you look at the average life expectancy of an adult (i.e., ignore those that died before becoming adult, say we start looking at 20 year olds) you find that an average adult can easily expect to live into their 60’s. There is decent evidence that this trend goes all the way back to the stone age, so if you survived long enough to raise children you were favored to live long enough to raise grandchildren and perhaps (since the species used to breed quite early back then) even great grandchildren. Why would evolution favor what on the surface appears to be behavior that provides no value to immediate survival and breeding? That is what the article addresses.
The idea is that because (fairly unique amongst animal species) humans are born with very little in the way of instincts and require, in addition to extensive care as infants, extensive training as youths, having some ‘elder statesmen’ (and women) around could vastly improve the opportunities for the ‘tribe’ (it is thought that the majority of ‘tribe’ in the stone age era were made up of family units, much like lion prides and elephant herds today) to survive. Because it might take decades of time to develop the detailed hunting and gathering skills for optimal survival it is plausible, from an evolutionary standpoint, that women would be given a break from child bearing fairly early (and by extension, monogamous males would also be given that same break) so they could focus on training the next generation. There are plenty of examples where what is optimal for the species is at odds with what is optimal for the individual (think of all those sterile (female) worker bees and ants). This would appear to be a similar case, though the ties are closer as the old folks would, for the most part, be directly assisting their own genes in already existing future generations.
So, the gist of the article is that non-breeding ‘old people’ are, in fact, critical to the evolution of our species. Take that you whipper snappers!
