Darwin's Theory of Sexual Selection 169 
a numerous progeny, but for the presence of better-endowed | 
males. We may may infer that this would be the case, because 
the females, which are unarmed and unornamented, are able to 
survive and procreate their kind. Secondary sexual charac- 
ters of the kind just réferred to will be fully discussed in the 
following chapters, as being in many respects interesting, 
but especially as depending on the will, choice, and rivalry of 
the individuals of either sex. When we behold two males 
fighting for the possession of the female, or several male birds 
displaying their gorgeous plumage, and performing strange 
antics before an assembled body of females, we cannot doubt 
that, though led by instinct, they know what they are about, 
and consciously exert their mental and bodily powers.” 
This general statement gives an idea of the class of phe- 
nomena that Darwin proposes to explain by the theory of sex- 
ual selection. The close resemblance between this process 
and that of artificial selection may be gathered from the fol- 
lowing statement : — 
“Just as man can improve the breed of his game-cocks by 
the selection of those birds which are victorious in the cock- 
pit, so it appears that the strongest and most vigorous males, 
or those provided with the best weapons, have prevailed 
under nature, and have led to the improvement of the natural 
breed or species. A slight degree of variability leading to 
some advantage, however slight, in reiterated deadly contests 
would suffice for the work of sexual selection ; and it is certain 
that secondary sexual characters are eminently variable. Just 
as man can give beauty, according to his standard of taste, to 
his male poultry, or more strictly can modify the beauty orig- 
inally acquired by the parent species, can give to the Sebright 
bantam a new and elegant plumage, an erect and peculiar car- 
riage — so it appears that female birds in a state of nature have, 
by a long selection of the more attractive males, added to their 
beauty or other attractive qualities. No doubt this implies 
powers of discrimination and taste on the part of the female 
