Whatever the details here I agree that evolutionary psychology is junk science or at least greatly abused. Wrt propensity for violence, I believe it depends more on the societies & politics in question. E.g. Plains Indians, esp the Comanche, and south-western groups such as the Apache had developed not only elite warrior classes, but extreme methods of torturing their enemies.

Then of course the Aztecs & their religion of human sacrifice, which made them countless enemies among their neighbors.

Some of histories bloodiest wars took place in China during the Three Kingdoms War (36 - 40 million killed) or the later An Lushang Rebellion—casualty figures vary on this latter one, but between them they might have caused more deaths than WWII.