I have read somewhere that the diving reflex is the automatic
lowering of the rate of cellular oxygen consumption upon immersion
in water. Because this is a metabolic reflex in the cytoplasm of
the cells, it cannot be learned behavior, but must be genetic in
origin. Many aquatic mammals have this metabolic reflex, but only one
primate displays anything like this behavior: Homo sapiens. Or at least
that's what I've read. I had the impression that this was one of the key
pieces of evidence for a primarily aquatic environment for one of the
ancestor clades of Homo sapiens, the other one being the fact that the
pattern of (vestigial) body hair on human beings is designed for water
flow and rapid draining and drying. This pattern is completely unlike
the pattern of body hair growth observed in all other primate species.
I'm sorry I don't have bibliographic references for this; as a result, I
have to prevent this as mere hearsay, but if anyone has any further
information supporting or confuting these assertions, I'd be very
interested in hearing about it.
-- Eric Watt Forste ++ arkuat@pobox.com ++ http://www.pobox.com/~arkuat/