Two types of choices seem to me to have been crucial in tipping the outcomes [of the various societies' histories] towards success or failure: long-term planning and willingness to reconsider core values. On reflection we can also recognize the crucial role of these same two choices for the outcomes of our individual lives.

Many of our problems are broadly similar to those that undermined ... Norse Greenland, and that many other past societies also struggled to solve. Some of those past societies failed (like the Greenland Norse) and others succeeded ... The past offers us a rich database from which we can learn in order that we may keep on succeeding.

History as well as life itself is complicated -- neither life nor history is an enterprise for those who seek simplicity and consistency.

The history of interactions among disparate peoples is what shaped the modern world through conquest, epidemics and genocide. Those collisions created reverberations that have still not died down after many centuries, and that are actively continuing in some of the world's most troubled areas.

...neither life nor history is an enterprise for those who seek simplicity and consistency.

Not until the beginning of the 20th century did Europe's urban populations finally become self-sustaining: before then, constant immigration of healthy peasants from the countryside was necessary to make up for the constant deaths of city dwellers from crowd diseases.

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.

Rhino-mounted Bantu shock troops could have overthrown the Roman Empire. It never happened.

The combination of government and religion has thus functioned, together with germs, writing, and technology, as one of the four main sets of proximate agents leading to history's broadest pattern.