Two evolutionary episodes

Michael Tomasello in his book, The Natural History of Human Morality argues with good data that humans are more cooperative and the simians more competitive, so how might we have evolved just so?  Here are two possibilities.  First here’s a story from the NYT on a group of chimpanzees who have moved from the forests to the savannah, from shady, cool environs with lots of fruit to sunny, hot grasslands where food is harder to come by:  https://www.nytimes.com/2018/04/27/science/chimpanzees-savanna-evolution.html.  Why the move? Perhaps their leaders had a yen for new, less crowded surrounds, sort like Daniel Boone or, as I have posted here periodically, those who settled the Andes or the Himalayas or the Artic. Perhaps they were a small group threatened by a larger and more belligerent group and so sought out safety in a place the others did not want.  The researchers gathered the chimps’ urine, no small undertaking in a hot, dry environment.  Even to get close enough to see them micturate and then collect the samples took 4 years of gentle contact so that the chimps became more comfortable with human presence. This is good, patient research. The urine showed that they were getting enough food but that their lives were stressful enough so that stress hormones were consistently elevated.

Now this is important because elevated stress hormones over the long haul can lead to health problems—the body and mind sort of wear out and grow thin with that load of stress.  Burn out we call it.  A sustainable life style would demand measures taken to lessen the stress, e.g., moving on, or behavioral change to cope with the conditions more effectively.  These chimps have changed their foraging behaviors to do more at night, avoiding the heat, though their species specific pattern is more activity in the daytime.  These chimps take a siesta during the heat of the day.  Of course at night more big predators may be about, so group communication becomes more important, as does having an escape plan. Then I thought about how we cooperative creatures cope with stress through social means, providing emotional support, increased creature contact, sharing the good stuff, etc., and I wondered about the genes promoting such behaviors increasing as the savannah chimps reproduce over the generations.  That is one episodic way we could have become more cooperative creatures.

The second episode comes from a new book I am reading, The Encultured Brain. I will say more about it later but now I want to cite a study of a baboon population reported therein. Baboon society is notably harsh by our standards; social order is based upon coercive and aggressive actions by the alphas.  A longitudinal study of one group, however, showed that after most of the alphas died in a virulent epidemic, the group now led by the non-alphas (betas?) became more peaceful and cooperative:  less fights, more grooming and sharing.  Further, new baboons that joined the group adapted their behaviors to this new ‘habitus’ and these changes have persisted over some years now.  I presume that the alphas were more susceptible to the disease for some reason (the heightened stress of leading by force? Like our type A behavior people die more from heart attacks, etc.) and the betas liked their way of interacting, having developed increased empathy from their lower position and perspective on the social scale.   A stretch there, I know, but a viable hypothesis nonetheless.

I read somewhere that the meek shall inherit the earth, and despite much data contrary to that, when I ponder these studies, I think maybe so.  Maybe so.  Travel on.

 

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