The broadest pattern of history - namely, the differences between human societies on different continents - seems to me to be attributable to differences among continental environments, and not to biological differences among peoples themselves.

Why did human development proceed at such different rates on different continents for the last 13,000 years?

For anyone inclined to caricature environmental history as 'environmental determinism,' the contrasting histories of the Dominican Republic and Haiti provide a useful antidote. Yes, environmental problems do constrain human societies, but the societies' responses also make a difference.

Guns, Germs, and Steel: The Fates of Human Societies.

Human societies vary in lots of independent factors affecting their openness to innovation.

All human societies go through fads in which they temporarily either adopt practices of little use or else abandon practices of considerable use.