210 Evolution and Adaptation 
other hand, with wolves, foxes, and apparently American 
squirrels, both sexes are occasionally born black. Hence it 
is quite possible that with some mammals a difference in 
color between the sexes, especially when this is congenital, 
may simply be the result, without the aid of selectidn, of 
the occurrence of one or more variations, which from the 
first were sexually limited in their transmission. Neverthe- 
less it is improbable that the diversified, vivid, and con- 
trasted colors of certain quadrupeds, for instance, of the 
above monkeys and antelopes, can thus be accounted for.” 
Finally, the case of man must be considered from the 
point of view of sexual selection, for Darwin claims that 
man has acquired a number of his secondary sexual char- 
acters in this way. For instance, the beard is an excellent 
case of a secondary sexual character. Darwin’s interpretation 
is that the beard has been retained, or even developed, 
through the selection by the females of those males that 
had this outgrowth best developed. Conversely, the absence 
of hair on the face of the female is supposed by Darwin to 
have been brought about by men selecting those women 
having less hair on their faces. The greater intellect, 
energy, courage, pugnacity, and size of man are the outcome 
of the competition of the males with each othef, since the 
individual excelling in these qualities will be able to select 
the most desirable wife, or wives, and it is assumed will, 
therefore, leave more descendants. The standard of beauty 
has been kept up by men selecting the most beautiful women 
in each generation (the fate of the other married women is 
ignored), and this beauty is supposed to have been transmitted 
primarily to their daughters, but also to their sons. 
Although all these forms of selection are imagined to be 
acting in man, either alternately or simultaneously, yet Dar- 
win recognizes in man a number of checks to the action 
of sexual selection: amongst savages, the so-called com- 
munal marriages ; second, infanticide, generally of the young 
