The Descent of Man

suckling their infants during a long time; but it
is highly probable that savages, who often suffer
much hardship, and who do not obtain so
much nutritious food as civilised men, would
be actually less prolific. I have shewn in a former
work (58. 'Variation of Animals and Plants
under Domestication,' vol ii. pp. 111-113, 163.),
that all our domesticated quadrupeds and
birds, and all our cultivated plants, are more
fertile than the corresponding species in a state
of nature. It is no valid objection to this conclusion
that animals suddenly supplied with an
excess of food, or when grown very fat; and
that most plants on sudden removal from very
poor to very rich soil, are rendered more or less
sterile. We might, therefore, expect that civilised
men, who in one sense are highly domesticated,
would be more prolific than wild men.
It is also probable that the increased fertility of
civilised nations would become, as with our
domestic animals, an inherited character: it is at
least known that with mankind a tendency to