In less than two weeks, the ten year anniversary of the deadliest terror attack on U.S. soil—9/11—will be upon us.

In the past decade, there has been much debate and discussion about the root causes of terrorism and violent extremism. There has also been considerable scientific study of the matter.

Fortunately, Point of Inquiry recently caught up with the anthropologist Scott Atran, a world leader in this research. Atran has met with terrorists face to face. He has interviewed mujahedin, met with Hamas, talked to the plotters of the Bali bombing-and sometimes found his life at risk by doing so.

There’s probably nobody better if you want to talk about terrorism, what motivates it, and how these extremes fit within the broad tapestry of human nature.

Scott Atran is a research director in anthropology at the French National Center for Scientific Research, and holds a variety of appointments at other academic institutions. He’s also the author of several books including In Gods We Trust: The Evolutionary Landscape of Religion and Talking to the Enemy: Faith, Brotherhood, and the (Un)Making of Terrorists. He has published frequent op-eds in the New York Times and his research has been published in Science, the Proceedings of the National Academy of Sciences, and other leading publications.