> Take walking upright as an example. At what point and by what
> mechanism did it become automatic and instinctive behavior
> instead of a "See, look what I can do!" thing?
I would think not so much instinctive behavior as a purely physiological mechanism that allowed selective advantage as climate changed and our ancestors moved from living in trees to open savannah?
Pretty soon, everyone was doing it!
I'm not sure if you've read anything on the controversy over bipedalism leading to bigger brains or the other way around?
~Hunter S. Thompson