All recognized famous inventors had capable predecessors and successors and made their improvements at a time when society was capable of using their product.

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.

But this was the only way of life that humans knew for their first 6m years on the planet. In giving it up over the past few thousand years, we have lost our vulnerability to disease and cold and wild animals, but we have also lost good ways to bring up children, look after old people, stave off diabetes and heart disease and understand the real dangers of everyday life.

In contrast [to trees and fish], oil, metals, and coal are not renewable; they don't reproduce, sprout, or have sex to produce baby oil droplets or coal nuggets.

We study the injustices of history for the same reason that we study genocide, and for the same reason that psychologists study the minds of murderers and rapists... to understand how those evil things came about.

We're uncomfortable about considering history as a science. It's classified as a social science, which is considered not quite scientific.

Technology causes problems as well as solves problems. Nobody has figured out a way to ensure that, as of tomorrow, technology won't create problems. Technology simply means increased power, which is why we have the global problems we face today.