what is the poets attittude towards, mankind hold on the planet?

Frost infers that man must be favored to a certain degree or the population of mankind could not have steadily increased.

"Take nature altogether since time began,

Including human nature, in peace and war,

And it must be a little more in favor of man,

Say a fraction of one percent at the very least,

Or our number living wouldn’t be steadily more,

Our hold on the planet wouldn’t have so increased."