Mike Tyson to Lennox Lewis: "I'm gonna eat your children"

Scientists have known for a while that chimapanzees (our closest genetic relative) will get organized and hunt in coordinated groups for other monkeys. In some cases, warring troops of chimps would have treetop battles, and any young or baby monkeys captured would be ritualistically eaten.

Up until recently, it was believed that Bonobos, our second-closest living genetic relative, was a peaceful creature that engaged in a more vegetarian, egalitarian lifestyle. As recently as 2006, many, including Frans de Waal, argued that had humans discovered Bonobos first and chimps later, we might fundamentally think differently about our species and whether or not we were born from violence.
Now scientists have discovered that Bonobos also occasionally hunt other primates. Previously the Bonobos were considered the 'hippy' apes because of their pleasant, non-violent nature.

Most anthropologists now agree that modern humans and neanderthals coexisted on this planet for a while, and at some point the neanderthals vanished. Rival theories conclude that modern humans either mixed (read: interbred) with them or possibly killed them off.

Given that our two closest living cousins engage in primate hunting and ritualistic cannibalism, is it really so hard to believe that our ancient ancestors saw the crude, less crafty neanderthals in the same ecological niche as themselves and decided to hunt and ritualistically kill their children? I think it's self-loathing that prevents many humans from accepting the plausability of this idea; no one wants to think our species is the dominant species on this planet because were took our genetic family's penchant for infanticide and fratricide and expanded it into genocide.