>This is the point. Instincts developed to keep you alive in a world where the classic laws of the jungle where true.

This is so very true. For example, the act of withdrawing from the TTP was an own-goal by the US against China. However this required relatively detailed understanding of the trading relationships and geopolitics of the region. It's much easier to appeal to base emotion - "strong man good for tribe, working with outsiders not good" - to gather support for what is essentially an act that furthers your opponents goals.