War seems to be omnipresent in human history and despite the number of people who have argued that the world is getting ever more peaceful, it remains a reality for millions of people today.

Margaret MacMillan is Emeritus Professor of International History at the University of Oxford and a world–renowned expert on history and international relations. Nick Spencer speaks to her about her book 'War: How conflict shaped us' which looks at how humans have fought and made peace with one another for millennia, and explores what this says about who we are.