sexes of as many animals as possible; but the materials are scanty. I
will here give only a brief abstract of the results, retaining the
details for a supplementary discussion, so as not to interfere with the
course of my argument. Domesticated animals alone afford the means of
ascertaining the proportional numbers at birth; but no records have
been specially kept for this purpose. By indirect means, however, I
have collected a considerable body of statistics, from which it appears
that with most of our domestic animals the sexes are nearly equal at
birth. Thus 25,560 births of race-horses have been recorded during
twenty-one years, and the male births were to the female births as 99.7
to 100. In greyhounds the inequality is greater than with any other
animal, for out of 6878 births during twelve years, the male births
were to the female as 110.1 to 100. It is, however, in some degree
doubtful whether it is safe to infer that the proportion would be the
same under natural conditions as under domestication; for slight and
unknown differences in the conditions affect the proportion of the
sexes. Thus with mankind, the male births in England are as 104.5, in
Russia as 108.9, and with the Jews of Livonia as 120, to 100 female
births. But I shall recur to this curious point of the excess of male
births in the supplement to this chapter. At the Cape of Good Hope,
however, male children of European extraction have been born during
several years in the proportion of between 90 and 99 to 100 female
children.
For our present purpose we are concerned with the proportions of the
sexes, not only at birth, but also at maturity, and this adds another
element of doubt; for it is a well-ascertained fact that with man the
number of males dying before or during birth, and during the first two
years of infancy, is considerably larger than that of females. So it
almost certainly is with male lambs, and probably with some other
animals. The males of some species kill one another by fighting; or
they drive one another about until they become greatly emaciated. They
must also be often exposed to various dangers, whilst wandering about
in eager search for the females. In many kinds of fish the males are
much smaller than the females, and they are believed often to be
devoured by the latter, or by other fishes. The females of some birds
appear to die earlier than the males; they are also liable to be
destroyed on their nests, or whilst in charge of their young. With
insects the female larvae are often larger than those of the males, and
would consequently be more likely to be devoured. In some cases the
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