If you look at history, cultures that have managed to form a wide group identity have wiped out cultures that relied on close, tribe-like cooperation. Here's a

If you look at history, cultures that have managed to form a wide group identity have wiped out cultures that relied on close, tribe-like cooperation. Here's a short clip from Sapolsky's lectures on behavioural evolution about this: https://www.youtube.com/watch?v=QQKTnau5AEY https://www.youtube.com/watch?v=QQKTnau5AEY I originally watched the whole lecture course, so I don't know how well the point gets across in this clip, but I highly recommend his lectures for this and other related subjects.