I'd rather spend my leisure time doing what some people call my work and I call my fun.

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.

Even to this day, no native Australian animal species and only one plant species-the macadamia nut-have proved suitable for domestication. There still are no domestic kangaroos.

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

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.

Bird taxonomy is a difficult field because of the severe anatomical constraints imposed by flight. There are only so many ways to design a bird capable, say, of catching insects in mid-air, with the result that birds of similar habitats tend to have very similar anatomies, whatever their ancestry. For example, American vultures look and behave much like Old World vultures, but biologists have come to realize that the former are related to storks, the latter to hawks, and that their resemblances result from their common lifestyle.

Although native Africans domesticated some plants in the Sahel and in Ethiopia and in tropical West Africa, they acquired valuable domestic animals only later, from the north.