No one set out to domesticate humans, but…
We humans domesticated ourselves, too – and changed our faces and bodies in the bargain – Sam Kean @sam_kean
…. with our reduced jaws, flat faces, and lower male aggression, humans are as tame as many of the animals we live with. Like dogs, cows, and horses, we show many of the physical traits that emerge during animal domestication. The accompanying changes in behavior, especially among men, might have helped humans evolve more complex language, live atop each other in cities, and work together to create sophisticated cultures.
Science 24 October 2014:
Vol. 346 no. 6208 pp. 405-406
By favoring more tolerant, less antagonistic individuals, natural selection reshaped both our behavior and our appearance, say researchers at the first-ever symposium on self-domestication of humans (see http://carta.anthropogeny.org/symposia/past_list)
…The view of humans as domesticated dates back to 1871, when Charles Darwin wrote that “[m]an in many respects may be compared with those animals which have long been domesticated.”
…. others have confirmed a “domestication syndrome.”
In a study in Current Anthropology in August, paleoanthropologist Robert Franciscus of the University of Iowa in Iowa City and his colleagues identified some of the same changes in recent human evolution. The team analyzed the projection of the brow ridge, facial shape, and cranial volume of 13 early Homo sapiens that lived before 80,000 years ago; 41 modern humans that lived 38,000 to 10,000 years ago; and skulls from a global sample of 1367 recent humans. They found that brow ridges shrank and faces shortened during the past 80,000 years, as our ancestors began to exhibit symbolic behavior and spread around the world. Cranial volume also diminished, particularly after the invention of agriculture about 10,000 years ago.
All of these changes tend to make male faces look more like female ones, Franciscus noted at the meeting, and are linked to lower testosterone levels.
… so many domesticated animals exhibit “neoteny”: They retain juvenile traits as adults. Mature dogs look like wolf pups, and humans look more like chimp infants than chimp adults, researchers noted at the meeting.
…Ethnologists have observed that hunter-gatherers kill men who steal wives or kill others. As social ties became more important to survival, Wrangham thinks, human ancestors may have inflicted the same kind of capital punishment, weeding out males who acted with intense and confrontational aggression. This doesn’t mean that humans are not “a dastardly species,” capable of war and torture, he noted, only that selection favored males who could work together, whether for peaceable ends or to carry out “low-arousal” or coalitional aggressive acts such as war.