Was discussing this with one of my Prof's the other day... He was lecturing about survival of the fittest and it occurred to me maybe it's survival of the meanest! He claimed that there were several species that were poised on the edge of becoming the next top predator when humans who seem weaker and less likely suddenly jump up and take over... It occurred to me that it may be because humans are always so pissed and ready to kill anything that moves!
Think of it this way if a human kills a lion what happens? Nothing the human eats the lion and goes about his business in his swanky new lion skin coat! Do all the other lions plot to kill him and all his friends? No, usually not! With humans its different we have a WAY over blown revenge gene! Kill one of us and were wiping out your whole species!!!! Just thought this was interesting and may be an explanation of why humans are at the top of the heap!