The Descent of Man

nious manner. "Let us for the purpose of illustration
take three families as representing an
average of the entire tribe; say that one mother
gives birth to six daughters and no sons; a second
mother has six sons only, whilst the third
mother has three sons and three daughters. The
first mother, following the tribal custom, destroys
four daughters and preserves two. The
second retains her six sons. The third kills two
daughters and keeps one, as also her three
sons. We have then from the three families,
nine sons and three daughters, with which to
continue the breed. But whilst the males belong
to families in which the tendency to produce
sons is great, the females are of those of a converse
inclination. Thus the bias strengthens
with each generation, until, as we find, families
grow to have habitually more sons than daughters."
That this result would follow from the above
form of infanticide seems almost certain; that is