172 Evolution and Adaptation 
“But it is difficult to understand why the males of species, 
of which the progenitors were primordially free, should in- 
variably have acquired the habit of approaching the females, 
instead of being approached by them. But in all cases, in 
order that the males should seek efficiently, it would be 
necessary that they should be endowed with strong passions ; 
and the acquirement of such passions would naturally follow 
from the more eager leaving a larger number of offspring 
than the less eager.” 
Thus we are led to the rather complex conclusion, that 
the more eager males will leave more descendants, and those 
that are better endowed with ornaments will be the ones 
selected. But unless it can be shown that there is some 
connection between greater eagerness and better ornamenta- 
tion, it might often occur that the less ornamented were the 
more eager individuals, in which case there would be an 
apparent conflict between the two acquirements. 
After giving some cases of the greater variability of the 
males, in respect to characters that are not connected with 
sexual selection, and presumably not the result of any kind 
of selection, Darwin concludes: “Through the action of 
sexual and natural selection male animals have been rendered 
in very many instances widely different from their females; 
but independently of selection the two sexes, from differing 
constitutionally, tend to vary in a somewhat different man- 
ner. The female has to expend much organic matter in the 
formation of her ova, whereas the male expends much force 
in fierce contests with his rivals, in wandering about in 
search of the female, in exerting his voice, pouring out 
odoriferous secretions, etc.: and this expenditure is gen- 
erally concentrated within a short period. The great vigor 
of the male during the season of love seems often to in- 
tensify his colors, independently of any marked difference 
from the female. In mankind, and even as low down in the 
organic scale as in the Lepidoptera, the temperature of the 
