On Wednesday 21st June, the Colombian government agreed to a ceasefire with the country’s largest rebel group. For most people, this story would have passed unnoticed, buried amongst the headlines. That’s a pity. Not only does it mark the end of a 50 year old war that has killed more than 220,000 people, it also signals the end of official armed conflict in the entire western hemisphere of the planet. It means that all of the war in the world is now contained to an arc stretching from Nigeria to Pakistan, containing less than a sixth of the world’s population. If you can tear your attention away from the 24 hour news cycle, you’ll be astonished to hear that we are experiencing one of the least discussed, yet most remarkable cultural shifts of all time: war, one of our species’ most abiding and defining social practices, is at its lowest ebb ever.