CHAPTER X 
SEXUAL SELECTION, ASSORTATIVE MATING AND 
THE DIFFERENTIAL MARRIAGE RATE 
“She’s that sort,” declared my Emma. ‘When you get them slim 
maidens, so quick-eared and quick-eyed as a mouse, with full lips 
that move and twinkle to their thoughts, and pretty, sly, sleepy eyes, 
same as Phillipa have got, then you can take it that men interest ’em 
more than any created thing. And they interest men, because nothin’s 
so lightning quick as a man to answer that sort of a signal.”’ Eden 
Phillpotts, Chronicles of St. Tid. 
As is well known Mr. Darwin attempted to explain the develop- 
ment of many of the secondary sexual characters which distin- 
guish the males from the females of higher animals as the result of 
the action of sexual selection. This term was used by Darwin to 
describe two very different kinds of selective activity; in one the 
outcome was based upon the “law of battle” or the struggle 
between rival males, the female falling as a matter of course to the 
lot of the victor; in the other mode of selection, the female is 
supposed to choose from among rival suitors the one whose 
charms make the strongest appeal. The law of battle is essen- 
tially a form of natural selection, although it does not as a rule 
result in the actual death of the unsuccessful contestant. It offers 
a very plausible explanation of the development of horns, tusks, 
greater strength and various offensive and defensive features that 
characterize the male sex of many animals. These endowments 
are directly useful in keeping the stock of their possessors, if not 
their possessors themselves, from extinction, and their develop- 
ment would naturally be favored by selection. But with sexual 
selection of the other type in which female volition forms an 
essential element, the outcome is usually the development of 
characteristics that charm the senses instead of directly aiding 
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