The fifth in a series of Gifford Lectures by Professor Michael Gazzaniga. Once the self emerges, look around. You are not alone; there are others—more than 6 billion of us now, up from 150 million in 200 BC. When agriculture was invented in 10,000 BC, there were only 4 million humans. Our species evolved in a social landscape that required our ancestors to think about the other guy and to adopt strategies that facilitated success in this social setting. Naturally, this led to an explosion of social processes, everything from the domestications of plants and animals in order to enable sedentary societies, to specialization of skills, to simple exchange of goods. Suddenly rules and knowledge of others’ minds became necessary, even indispensable. Indeed, a moral framework for assuring fairness and trust began to emerge. Recorded on 20 October 2009 at Playfair Library.