QUOTE : What is fascinating is that it’s at this juncture, after the end of the last ice age, that wars first break out. Just as we started settling down in one place, archaeological research has determined, we built the first military fortifications. This is also when the first cave paintings appeared that depict archers going at each other, and legions of skeletons from around this time have been found to bear clear traces of violent injury.25 How did it come to this? Scholars think there were at least two causes. One, we now had belongings to fight over, starting with land. And two, settled life made us more distrustful of strangers. Foraging nomads had a fairly laid-back membership policy: you crossed paths with new people all the time and could easily join up with another group.26 Villagers, on the other hand, grew more focused on their own communities and their own possessions. Homo puppy went from cosmopolitan to xenophobe.