Both memoir and call-to-arms, Tribes explores both the benign and malign effects of our need to belong. It can manifest itself in positive ways, enabling us to collaborate and achieve great things that individuals alone cannot. And yet in recent years, globalisation and digitisation have led to new, more pernicious kinds of tribalism. A fascinating and perceptive analysis of not only the way the world works but also the way we really are. David Lammy has been MP for Tottenham since 2000.