Yesterday, Maj. Nidal Hasan was sentenced to death for killing 13 people and injuring more than 30 in a 2009 attack at Fort Hood, Texas. In the almost four years since that event, 16 more mass shootings have occurred in the United States, with fatalities ranging from four to 28, according to data compiled by Mother Jones.
Each such event inevitably begets the question: What motivates killers? What can turn a person to such an act of violence? A 2009 TED talk by neuroscientist Jim Fallon may hold one of the keys to the enduring mystery of human violence.
Fallon explains that after examining the brains of around 70 psychopathic killers, certain common traits became evident -- every single brain showed signs of damage. Fallon was even able to pinpoint a specific area where murderers had experienced trauma: the orbital cortex. Furthermore, he found that the age at which the damage occurred was also a sign of whether someone would become a killer or not.
Watch the whole talk to find out more about the fascinating -- and disturbing -- connection between genes and the propensity to become a mass murderer.