Robin Dunbar is an anthropologist, evolutionary psychologist, head of the Social and Evolutionary Neuroscience Research Group at the University of Oxford and an author.

Most animals need friends to survive. But no other animal has as layered and complex a social life as humans. The last 2 million years from trees to plains to apartments has caused huge changes to the setup of our social groups, and it's a fascinating story.

Expect to learn why any group size over 90 ends up with more people being killed than being born, why men don't have a best friend forever but women do, the link between human brain size and social groups, how male and female friendships differ, why the modern world has the most loneliness ever, what the single largest impact on your health is and much more...