For scientist, the only source of morality must be our genes. Morality is the ultimate emergent property of the gene, says Peter Atkins. Whatever leads to a stable society leads to a sense of morality. Primatologist Frans de Waal, however, says he would never trust science to explain morality - you can construct a perfectly logical argument for slavery. George Ellis argues that evolutionary and neuroscientific arguments about morality always introduce by the back door a concept of the good life which they take for granted as being a good thing. Who says living together is a good thing? And if 'good' means happy, why not give everyone drugs to make them feel happy? Is that a moral life? According to evolutionary theory and the survival of the fittest, cheaters, who will compete ruthlessly, should be the most successful survivors. But Harvard Biologist and Mathematician Martin Nowak uses an extraordinary graphic to illustrate to Ard and David his mathematical calculation that collaborators and competitors are locked together in the evolutionary process, a truth which has been observed in the field by primatologists for decades.