When two crayfish meet, they usually fight. One would say that perhaps they might not at a future time, but without some mutation it is not likely that they will lose this trait. And perhaps our species is not likely to forgo war without some psychic mutation which at present, at least, does not seem imminent. And if one place the blame for killing and destroying on economic insecurity, or inequality, on injustice, he is simply stating the proposition in another way. We have what we are. Perhaps the crayfish feels the itch of jealousy, or perhaps he is sexually insecure. The effect is that he fights.
John Steinbeck p.15