I decided that now is the time to start doing the things that really interest me and I find important. It was in the 10 years of the MacArthur grant that I began working on my first book... and I began putting more work into environmental history.

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

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.

Throughout history, adultery has had few rivals as a cause of murder and human misery. The reason we tend to resemble our mates is that many of us are looking for someone who reminds us of our parent or sibling of the opposite sex, who in turn resembles us.

No government is here forever. And there are other forces - the most potent force in our society, in fact, big business - doing good for the environment.

Lest those islands still seem to you too remote in space and time to be relevant to our modern societies, just think about the risks... of our increasing globalization and increasing worldwide economic interdependence.

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.