Tribal war drove human evolution of aggression

PhysOrg ^ | September 9, 2008 | Lisa Zyga

[SunkenCiv]

However, as you might expect, there is a downside to belligerence and bravery. While both these traits offer advantages during war for a tribe, both traits are also considered high-risk social behaviors. An individual possessing the traits has a greater chance of dying, which means the tribe not only loses a warrior, but the death also opens a spot for another male to appropriate the first male's reproduction-enhancing resources.

This trade-off leads to another question: if an individual himself does not benefit from belligerence and bravery, but only his tribe, why would humans evolve this altruistic trait? The scientists explain that the answer is kinship: a human will take the risk of dying for close relatives since they carry very similar genetic material, and will pass that genetic material on for him.

[allmendream]

Many of those “deaths” are the degradation and slavery of those who you love and care about, better to be in your own grave than to be alive to witness it.

It is better to live on your feet than to die on your knees.

A brave man may die only once, a coward dies a thousand deaths.

[John Will]

Trade tends to do that. It seems you can either have soldiers or goods go across borders.