Friday, March 30, 2018

Birds have feathers

Birds are outside singing beautifully, and warm with their feathers.  Most primates have fur or something that keeps them warm (e.g. fat).  And we are alone among the 5,000 or so mammals in that we are naked.

We were made humorously aware of our sensitivity to nakedness when we saw the Cirque de Machine this week.  They are an acrobatic troupe from Quebec.  One of their routines had the 4 acrobats standing naked behind towels.  They exchanged and folded them and did amazing things, keeping us in suspense,  yet always keeping them covered.  

Scientists have a few reasons why humans became less and less hairy in six million years.  The latest theory is that fur was shed to get rid of external parasites. The advertisement of bare skin says "no fleas, lice or ticks on me!'.  Earlier theories had to do with not needing fur as we were more aquatic (like whales) and not needing fur as we lived in hot areas.   One theory, outlined in the said it was to keep our brains cooler.

And when did humans lose their fur? We distinguish it as fur, as we are covered in hair - about 5 million follicles on our body.  The theory on that was developed based on needing dark skin in Africa.  So as humans lost their fur, they needed the gene MC1R to keep their skin darker. In a few generations this version of the gene would have made a clean sweep through the population.  Based on the number of these 'silent mutations' in Africa, they calculated that the last sweep occurred 1.2 million years ago, when the human population consisted of a mere 14,000 breeding individuals.  This is a very interesting Scientific American article HERE.  

And when did we move on to wear clothes?  Supposedly the evidence comes from the evolution of lice, who evolved from head lice to clothing lice around 170,000 years ago.  

Here's the website for our fun acrobatic troupe where you can see a short video HERE with a momentary segment from the towel act.  

No comments:

Post a Comment