Do men commit murder because they are victims of a society gone haywire? Is gang violence the product of poverty? Overcrowding? Why is rape so prevalent across cultures? And what draws men into war?

In this ambitious book, Michael Ghiglieri, a biologist and protege of Jane Goodall, takes on these questions - and many others - in an attempt to unearth the roots of human aggression. Drawing on literally thousands of sources, from scientific journals to personal interviews, as well as his own experience as both a primatologist and a soldier, her explains why males are far more aggressive than females: male violence is largely innate, a product of millions of years of evolution.

But, he warns, we are not genetic robots, forever destined to rob, rape, and kill. Ghiglieri's message is ultimately a hopeful one: by acknowledging the biological underpinnings of human nature, and then moving toward policies that are based on this understanding, we can finally hope to end the vicious cycle of violence that plagues us.