My 16yo is having his wisdom teeth removed tomorrow. Blame it on human domestication.
The Economist explains the process. Domestication, whether it occurs in humans, foxes, or wolves, involves changes to "estradiol and neurotransmitters such as serotonin" (for example). These changes make humans less violent and better care givers and partners -- major survival advantages for a social animal. They also have unexpected side-effects, like shortened muzzles and flattened faces for wolves, foxes, (cows?) and humans.
Since domesticated humans out-compete undomesticated humans, the physiologic markers of domestication become selected for. They being to appear beautiful. Sex selection reinforces the domestication process.
It seems to be ongoing ...
... People also seem to be more beautiful now than they were in the past—precisely as would be expected if beauty is still evolving...
Which may be why we are becoming less violent.
Of course a shortened muzzle and smaller mandible have side-effects. Teeth in rapidly domesticating animals don't have room to move. Which is good news for orthodontists, and bad news for wisdom teeth.
- A link between autism and the domestication of humans and dog: "MET gene selection appears to be related to human and canine domestication, including sociability. Variants of it are associated with autism-like behavior."
- The canid domestication of homo sapiens brutalis