How humans came to dominate the Earth

Paul Ehrlich: First of all, genetically, we were a social animal that originally lived in trees, which gave us some of our most important characteristics, like eyes in the front of the head, binocular vision.

You’re listening to Paul Ehrlich of Stanford, explaining his ideas on why we humans dominate Earth.

Paul Ehrlich: We used to snatch insects in bushes, so we have very dextrous fingers. It’s a good thing that we came down out of the trees, because you can’t build a civilization in the trees. And we became an increasingly smart, social animal and did a wonderful job of taking over our environment.

Our genetic evolution gave us things like dextrous fingers and binocular vision. But Ehrlich says what put us over the top was our cultural evolution – learning to farm, learning language that we could write down, learning to change and manipulate our world.

Paul Ehrlich: It’s our cultural evolution, hopefully responding to our changes in the environment, that may very well save us. A good example of cultural evolution would be determination by all people to move as rapidly as possible to, say, a solar-hydrogen economy, rather than burning fossil fuels.

Paul Ehrlich is professor of biology and population studies at Stanford. His recent book is called The Dominant Animal: Human Evolution and the Environment.

Ehrlich said our ability to adapt is critical to meeting the challenges of a changing climate and degraded environment.

Paul Ehrlich: We’ve changed the entire environment, and our evolution is a response to our environment. Obviously, we are responding genetically. For instance, when some groups of human beings took up herding animals and drinking milk, the genetics of how we handle lactose changed.