The Descent of Man

From the several foregoing cases we have some
reason to believe that infanticide practised in
the manner above explained, tends to make a
male- producing race; but I am far from supposing
that this practice in the case of man, or
some analogous process with other species, has
been the sole determining cause of an excess of
males. There may be some unknown law leading
to this result in decreasing races, which
have already become somewhat infertile. Besides
the several causes previously alluded to,
the greater facility of parturition amongst savages,
and the less consequent injury to their male
infants, would tend to increase the proportion
of live-born males to females. There does
not, however, seem to be any necessary connection
between savage life and a marked excess of
males; that is if we may judge by the character
of the scanty offspring of the lately existing
Tasmanians and of the crossed offspring of the
Tahitians now inhabiting Norfolk Island.