1. I should have thought that any hunter-gatherers that didn't operate as a team when hunting would end up rather skinny.
2. I have read about some bod in New Guinea who brought a tribesman down to Port Moresby, who COULD NOT UNDERSTAND how the people on the street were NOT fighting each other. Nowadays I suppose it is sublimated by watching football on the telly. I'm quite sure that men are hardwired to stand up for 'us' and want to beat the sh1t out of 'them'.