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.

Twelve thousand years ago, everybody on earth was a hunter-gatherer; now almost all of us are farmers or else are fed by farmers. The spread of farming from those few sites of origin usually did not occur as a result of the hunter-gatherers' elsewhere adopting farming; hunter-gatherers tend to be conservative.... Instead, farming spread mainly through farmers' outbreeding hunters, developing more potent technology, and then killing the hunters or driving them off of all lands suitable for agriculture.

In fact, everywhere in the world there has been a flux between big and small societies. Big political units are constantly being formed, later to fragment. The individual pieces try to pull apart, and then they join together again. One sees that in Europe: There have been unifications and then dissolutions and reunifications. So in the long run, it's 10,000 steps toward amalgamation offsetting 9,999 steps toward falling apart again. In businesses and industries, I would guess that's also true.

In short, Europe’s colonization of Africa had nothing to do with differences between European and African peoples themselves, as white racists assume. Rather, it was due to accidents of geography and biogeography—in particular, to the continents’ different areas, axes, and suites of wild plant and animal species. That is, the different historical trajectories of Africa and Europe stem ultimately from differences in real estate.

In parts of Montana, salt concentrations in soil water, have reached those double those of seawater.

Eurasia ended up with the most domesticated animal species in part because it's the world's largest land mass and offered the most wild species to begin with.

African cavalry mounted on rhinos or hippos would have made mincemeat of European cavalry mounted on horses. But it couldnt happen.