Pets Vital to Human Evolution

Dogs, cats, cows and other domesticated animals played a key role in human evolution, according to a theory being published by paleoanthropologist Pat Shipman of Penn State University.

The uniquely human habit of taking in and employing animals -- even competitors like wolves -- spurred on human tool-making and language, which have both driven humanity's success, Shipman says.

"Wherever you go in the world, whatever ecosystem, whatever culture, people live with animals," Shipman told Discovery News.