In 2011, Harvard s Stephen Pinker published a major study on long-term trends in global violence. The Better Angels of Our Nature: Why Violence Has Declined has won widespread critical acclaim for its scope, originality and scholarship. But Professor Pinker s central claim that, we may be living in the most peaceful era in our species existence has become the focus of a wide-ranging and increasingly heated debate. The 2013 Human Security Report s analysis offers the most comprehensive review to date of this debate one that is as important as it is contested.