The Descent of Man

Dr. Forsyth Major also informs me that a fossil
skull, believed to be that of the female Bos
etruscus, has been found in Val d'Arno, which
is wholly without horns. In the Rhinoceros simus,
as I may add, the horns of the female are
generally longer but less powerful than in the
male; and in some other species of rhinoceros
they are said to be shorter in the female. (16. Sir
Andrew Smith, 'Zoology of S. Africa,' pl. xix.
Owen, 'Anatomy of Vertebrates,' vol. iii. p. 624.)
From these various facts we may infer as probable
that horns of all kinds, even when they
are equally developed in the two sexes, were
primarily acquired by the male in order to conquer
other males, and have been transferred
more or less completely to the female.
The effects of castration deserve notice, as
throwing light on this same point. Stags after
the operation never renew their horns. The male
reindeer, however, must be excepted, as after
castration he does renew them. This fact, as