All of our current environmental problems are unanticipated harmful consequences of our existing technology. There is no basis for believing that technology will miraculously stop causing new and unanticipated problems while it is solving the problems that it previously produced.

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.

The single most important problem is our misguided focus on identifying the single most important problem!

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.

The rate of human invention is faster, and the rate of cultural loss is slower, in areas occupied by many competing societies with many individuals and in contact with societies elsewhere.

Much of human history has consisted of unequal conflicts between the haves and the have-nots.

All human societies go through fads in which they temporarily either adopt practices of little use or else abandon practices of considerable use.