Early human beings... filled a special ecological niche: they were carnivorous primates of the African plains. ...When agriculture permitted the incr… - Edward O. Wilson

The pattern of human population growth in the 20th century was more bacterial than primate. When Homo sapiens passed the six billion mark we had already exceeded by perhaps as much as 100 times the biomass of any large animal species that had ever existed on the land. We and the rest of life cannot afford another 100 years like that.

Cultural change is the statistical product of the separate behavioral responses of large numbers of human beings who cope as best they can with social existence.

Ancient Mexico, like most forest-invested New World tropics, was deficient in the kind of large game that flourished on the plains of Africa and Asia. ...The situation was partially relieved by cannibalizing the victims of human sacrifice. ...The [ Aztec ] priesthood... sanctified it... immediately after their hearts had been cut out, the victims were systematically butchered like animals and their parts distributed and eaten.