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.
Evolucionaron para un mundo en el que la gente viviría en grupos muy pequeños, dificilmente conocerían a alguien sumamente diferente de ellos, tendrían vidas particularmente cortas en las que habrían muy pocas opciones y la prioridad más importante sería comer y procrear hoy.