In "Do I Need You?" Dr. David Eagleman explores how the human brain relies on other brains to thrive and survive. This neural interdependence begins at birth. Dr. Eagleman invites a group of babies to a puppet show to showcase their ability to discern who is trustworthy, and who isn't. Brain scans reveal that when we see someone in pain, we feel it too. Circuits within the brain's pain matrix light up in both cases. And this is the basis of empathy. Our social brain draws us together into groups. In groups humans have accomplished great things - from football games to music festivals, from peopling the world to building great civilizations. But there's a darker side. For every "in group" there is always an "out group." Dr. Eagleman's lab has shown that belonging to an "in group" means that at an unconscious level our brains care less about members of the "out group." He journeys to modern day Bosnia to hear from an eyewitness about what happened in 1995 when genocide returned to Europe. What could have allowed for such horrific group on group violence? Dr. Eagleman believes that neuroscience offers important answers. Dr. Lasana Harris at Leiden University has discovered that there are certain circumstances under which the human brain stops perceiving others as human, and when we perceive others as less than human it’s easier to ignore them, and it’s easier to suspend the moral and social rules we normally live by.