Wednesday, August 31, 2011

PBS Nova re-airs entire "Becoming Human"; science brings up some social and political dingers here


On August 31, PBS Nova re-aired its three part “Becoming Human”.  (Part 3 had been reviewed here Nov. 17, 2009).  Part 1 is “First Steps” and Part 2 is “Birth of Humanity”.  Graham Townsley and Barbara Burst wrote and directed.

Several important features were important to make humans what we are today.  The first feature may have been the ability to run a long time on two legs, full bi-pedism.  This seems to have been a way to conserve energy for the growing brain, which was a necessary adaptation to survive during times of rapid climate change.  (Both hours of the film show a provocative shot of a young male "Harvard" jogger with electrodes strapped to his leg to measure energy use.)   The filmmakers believe that warming and cooling climates (and recurrent droughts and wet periods) in small areas have happened frequently and forced predecessors of humans to make genetic adaptations that allow for better problem solving.  This may not agree with the current political debate on climate change.

The human brain demanded enormous amounts of energy, which could not be satisfied with plant food (in contrast to today, where heart-healthy diets emphasize our vegetarian origins).  Humans had to hunt and compete with other carnivores. One development was the loss of most body hair, at least in hot climates, so that humans could run and hunt for a long time during the midday when hairier carnivores overheated and slept.   (Humans have more than one type of lice, since head hair (and beard) and pubic hair are largely disconnected.)  Perhaps there is a cultural stereotype that hairless humans are smarter and more “evolved”.  On the other hand (a point not covered by the show), Caucasians, who generally developed in colder climates, often maintained some of the original body hair, especially males, where (besides the beard) could amplify distinguishing secondary sexual characteristics for mating, just as in birds where in many species males have brightly colored plumage.  

The second hour also covered the complex socialization of humans, which it says may have started with cooking around a fire.  It said that human mothers are more likely to abandon infants than other primates, unless they have complex systems of social support, which go beyond just (“right wing”) demands for stable marriage.

The link is here

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