The domestication syndrome
This is an interesting thought.Tame Theory: Did Bonobos Domesticate Themselves? A new hypothesis holds that the natural selection produced the chimpanzee's nicer cousin in much the same way that humans bred dogs from wolves By Ed Yong | January 25, 2012 | 26 Here is an excerpt from this article:
The similarities between bonobos and domesticated species dawned on Hare during a large departmental dinner, where he listened to Harvard University anthropologist Richard Wrangham hold forth on bonobos. "He was talking about how bonobos are an evolutionary puzzle," Hare recalls. "'They have all these weird traits relative to chimps and we have no idea how to explain them,'" Wrangham had noted. "I said, 'Oh that's like the silver foxes!' Richard turned around and said, 'What silver foxes?'" The foxes that Hare mentioned were the legacy of Russian geneticist Dmitri Belyaev. In the 1950s Belyaev started raising wild silver foxes in captivity and breeding those that were least aggressive toward their human handlers. Within just 20 generations, he had created the fox equivalent of our domestic pooches. Instead of snarling when humans approached, they wagged their tails. At the same time, their ears became floppier, tails curlier and skulls smaller.
Belyaev's experiments showed that if you select for nicer animals, the other parts of the domestication syndrome follow suit. Hare thinks that a similar process happened in bonobos, albeit without human intervention.
Rape, murder and warring neighbors are all regular aspects of chimp life. Bonobo societies, however, are far more peaceful. Hare thinks that the chimplike ancestors of bonobos found themselves in an environment where aggressive individuals fared poorly. By selecting for the most cooperative ones, evolution forged a "self-domesticated" ape, just as Belyaev produced domestic foxes by picking the most docile ones.
I suspect humans are like Bonobos, or were, at least, while living as hunter-gatherers. I am not so sure, however, if selection for "nice animals" who are less aggressive has been reversed since we began to exceed certain critical resource: population ratios in the past few thousand years.