The Descent of Man

acters eminently distinctive of him in comparison
with the lower animals.
Another most conspicuous difference between
man and the lower animals is the nakedness of
his skin. Whales and porpoises (Cetacea), dugongs
(Sirenia) and the hippopotamus are naked;
and this may be advantageous to them for
gliding through the water; nor would it be injurious
to them from the loss of warmth, as the
species, which inhabit the colder regions, are
protected by a thick layer of blubber, serving
the same purpose as the fur of seals and otters.
Elephants and rhinoceroses are almost hairless;
and as certain extinct species, which formerly
lived under an Arctic climate, were covered
with long wool or hair, it would almost appear
as if the existing species of both genera had lost
their hairy covering from exposure to heat. This
appears the more probable, as the elephants in
India which live on elevated and cool districts
are more hairy (87. Owen, 'Anatomy of Verte-