"- if you walk through a tropical rainforest, you don't see that much fighting - it all seems rather peaceful most of the time. Nature really likes cooperation."

It might look peaceful on the Discovery Channel, but have you ever walked in a real tropical rainforest? Everything has spikes, everything is poisonous, almost anything that moves will fight or flee at first sight - everything but the very largest and most dangerous things. It's not the organized warfare of humans, but rather a cosmic, bloody, free-for-all, with survival and replication the only criterion for success. Evolution is not only a Blind Idiot God, but also a very harsh and unsympathetic mistress.