Which elements in “the human drift” are typical of naturalist literature

The naturalist writing style incorporates scientific principles of objectivity and detachment. This is evident in “The Human Drift,” with its scientific examples:

These early drifts we conjecture and know must have occurred, just as we know that the first upright-walking brutes were descended from some kin of the quadrumana through having developed “a pair of great toes out of two opposable thumbs.”

Another common element of naturalist literature in “The Human Drift” is that human beings are considered practically “beasts,” savage and uncivilized:

In the misty younger world we catch glimpses of phantom races, rising, slaying, finding food, building rude civilisations, decaying, falling under the swords of stronger hands, and passing utterly away.

Naturalist writers believed that human beings and their lives are governed not just by their actions but also by forces of nature, such as flood and famine:

And man has been destroyed in other ways than by the sword. Flood, famine… are potent factors in reducing population—in making room… The failure of crops in Ireland, in 1848, caused 1,000,000 deaths. 

Naturalism is also based on the Darwinian principle of “the survival of the fittest.” London establishes this in the following sentences:

As soon as his evolution permitted, he made himself better devices for killing than the old natural ones of fang and claw. He devoted himself to the invention of killing devices.