They were evolved for a world in which people lived in very small groups, rarely met anybody who was terribly different from themselves, had rather short lives in which there were few choices and the highest priority was to eat and mate today.
Eles evoluíram para um mundo em que as pessoas viviam em grupos bem pequenos, raramente conheciam alguém que era muito diferente de si mesmos, tinham vidas relativamente curtas nas quais havia poucas escolhas e a máxima prioridade era comer e acasalar hoje.