At the same time, the reason for the individual's survival may lie very largely outside him.

Amongst the bees, for instance, a non-working type of insect survives to breed because the sterile workers do their duty by the hive.

So, too, that other social animal, man, carries on the race by means of some whom others die childless in order to preserve.

Nevertheless, breeding being a strictly individual and personal affair, there is always a risk lest a society, through spending its best too freely, end by recruiting its numbers from those in whom the engrained capacity to render social service is weakly developed.

To rear a goodly family must always be the first duty of unselfish people; for otherwise the spirit of unselfishness can hardly be kept alive the world.
Enough about heredity as a condition of evolution.