That is the drive of the argument.

And for this argument it can be said that it is possible to talk of it in terms of evolution or inevitable progress.
A perpetual tendency to touch fewer and fewer things might, one feels, be a mere brute unconscious tendency, like that of a species to produce fewer and fewer children.

This drift may be really evolutionary, because it is stupid.
Darwinism can be used to back up two mad moralities, but it cannot be used to back up a single sane one.

The kinship and competition of all living creatures can be used as a reason for being insanely cruel or insanely sentimental; but not for a healthy love of animals.

On the evolutionary basis you may be inhumane, or you may be absurdly humane; but you cannot be human.