S u m m a r y :
Instead of humans domesticating animals, humans were domesticating humans, back in the day.
The Selection Process
Before we domesticated animals, we, humans, domesticated ourselves: this was done through a process of selecting ‘tame’ humans over aggressive ones.
Choosing tameness over its opposite trait has been suggested by scientists for decades now. This selection process might have started at some time in the last 200,000 years, says Richard Wrangham, an evolutionary biologist and primatologist from Harvard University, one of the researchers who support the concept.
Tame Humans vs Aggressive Humans
Wrangham explains that tameness is defined as a lower reactive aggression, the latter term englobing the volatile temperament that is behind the behaviour whereby an animal is always ready to take on another at the slight provocation. As per this description, humans are relatively tame: we are not inclined to attacking just about anyone we come across. This would have been because humans with an excessive reactive aggression were selected against, thousands of years ago. Complex social skills would have enabled our ancestors to stand up against bullies. Thus, tame humans moved forward while their less endowed counterparts remained behind.
Taming Changes Genes
Self-domestication is not without consequence. The researchers who have proposed the hypothesis argue that the selection for tame humans led to genetic changes, as suggested by a number of studies, an occurrence that is eerily similar to what has happened in other species that have been domesticated by humans; for instance, features like the head and face shape are known to undergo modifications when taming occurs. Thus, tameness lead to other traits to develop.
According to proponents of the human taming idea, we actually look domesticated: our faces are shorter, with males resembling females, as opposed to other related species.
Domestication & Language
Taming humans would have paved the way to refined language. As the society was resistant against aggressive humans, it would eventually work better as a social species, explains linguistics expert Antonio Benítez-Burraco, from University of Huelva, whose research is focused on language evolution.
Early Homo sapiens could engage in complex thought processes while they lagged behind in language. But, with self-domestication, humans would have gradually developed into a creature able to communicate on higher and higher levels. This trend can actually be seen in other animals: birds, for instance, when domesticated, develop more complex songs as opposed to birds that remain in the wild.
Based on this, scientists suggest that other species might have self-domesticated as well to function better as a community. Wrangham mentions in a 2012 paper how bonobos are more peaceful than their more violent relatives, the chimpanzee.
[Image credits: Cleveland Museum Of Natural History, via Wikimedia Commons. Differences between a human skull (left), and a Neandertal one, suggest tameness in humans.]