A Bundle of Instincts

"It was (and is) common to think that other animals are ruled by "instinct" whereas humans lost their instincts and are ruled by "reason", and that this is why we are so much more flexibly intelligent than other animals. William James took the opposite view. He argued that human behavior is more flexibly intelligent than that of other animals because we have more instincts than they do, not fewer."

Leda Cosmides & John Tooby offer more here: Evolutionary Psychology: A Primer.