Why were there far more species of domesticated animals in Eurasia than in the Americas? The Americas harbor over a thousand native wild mammal species, so you might initially suppose that the Americas offered plenty of starting material for domestication.
Jared DiamondWhy is it that you white people developed so much cargo and brought it to New Guinea, but we black people had little cargo of our own?
Jared DiamondThe rate of human invention is faster, and the rate of cultural loss is slower, in areas occupied by many competing societies with many individuals and in contact with societies elsewhere.
Jared Diamond