316 
THE PRINCIPLES OF 
Part IL 
cases an inequality would be no advantage or disad- 
vantage to certain individuals more than to others ; and 
therefore it could hardly have resulted from natural 
selection. We must attribute the inequality to the 
direct action of those unknown conditions, which with 
mankind lead to the males being born in a somewhat 
larger excess in certain countries than in others, or 
which cause the proportion between the sexes to differ 
slightly in legitimate and illegitimate births. 
Let us now take the case of a species producing from 
the unknown causes just alluded to, an excess of one 
sex—' we will say of males — these being superfluous and 
useless, or nearly useless. Could the sexes be equalised 
through natural selection? We may feel sure, from all 
characters being variable, that certain pairs would pro- 
duce a somewhat less excess of males over females than 
other pairs. The former, supposing the actual number 
of the offspring to remain constant, would necessarily 
produce more females, and w r ould therefore be more pro- 
ductive. On the doctrine of chances a greater number 
of the offspring of the more productive pairs would sur- 
vive ; and these would inherit a tendency to procreate 
fewer males and more females. Thus a tendency to- 
wards the equalisation of the sexes would be brought 
about. But our supposed species would by this process 
be rendered, as just remarked, more productive ; and 
this would in many cases be far from an advantage 
for whenever the limit to the numbers which exist, de- 
pends, not on destruction by enemies, but on the amount 
of food, increased fertility will lead to severer competi- 
tion and to most of the survivors being badly fed. In 
this case, if the sexes were equalised by an increase in 
the number of the females, a simultaneous decrease in 
the total number of the offspring would be beneficial, 
or even necessary, for the existence of the species ; and 
