In this week’s Science there is and article about the role of “self domestication” in the  evolution of modern humans. The first-ever symposium on self-domestication was held in San Diego.

evolution by self-domestication
Homo sapiens & our most recent ancestor

The view of humans as domesticated dates back to 1871, when Charles Darwin wrote that “man in many respects may be compared with those animals which have long been domesticated.” …In a renowned study started back in the 1950’s, Russian researchers found that captive silver foxes bred for tameness also exhibited a suite of fur on their heads, curly tails, “feminized” faces with shorter snouts and floppy ears, and skulls in males that weren’t much longer than females.

Paleoanthropologist Robert Franciscus and his colleagues recently published a paper claiming that the well-known changes between our last ancestor, Homo heidelbergensis and modern humans mimic the changes seen in domesticated animals. and are linked to decreased testosterone levels secondary to selection for less aggression. The most celebrated speakers at the meeting were Richard Wrangham from Harvard and linguist Tecumseh Fitch, who wrote a paper theorizing that these changes are controlled by specific embryonic cells which have been altered by the fact that domestication selects for animals to develop more slowly which they feel triggered all these physical and hormonal changes.

Ardipithecus vs. Chimp canine teeth
Ardipithecus vs. Chimp canine teeth

I have long thought that self- domestication was the primary evolutionary mechanism that initiated our entire Hominin Tribe 6 million years ago. Far more explicitly direct changes indicating reduced aggression, such as reduced canines  between chimpanzees and Ardipithicus ramidus, are more significant than the indirect, “hormonal” differences shown in the images at the top.

marital conflict

During a decade that I was active in marital counseling I spent a great deal of time exploring the depth of complementarity of couples, much to their surprise. Through counseling, they realized that the differences that divided them had initially been the attraction. Perhaps the balanced “completion” of one another was evolved more for balancing their children’s temperaments than for the eventual harmony of their relationship.  I believe, more than reduced aggression, a balanced temperament in general is the hallmark of (self-)domestication. Those Russian foxes were domesticated by the simple formula of balancing their temperaments: not too aggressive AND not too fearful. Due to the unconsciousness nature of this process of selection in couples, and its depth of subtlety, I came away thinking that it was very ancient hominin trait.

Brad Pitt and Angela
Do these people have a hormone problem?

 It was Freud that discovered that one of our most characteristic traits is our hyper-sexuality. In this way we are more like bonobo apes than chimpanzees. As my sheep herder friend, who is an expert on domesticated animals, once told me, “John, animals don’t walk around thinking about sex all day.” It does not take a psychiatrist to figure out that a far more parsimonious explanation for our child-like physiques is due to the process of rampant sexual selection that has been loosed in our species. Everybody knows that our sexuality is all about, well, being cute, which is looking and acting young. As the Rabi said, “all the rest [including our putative reduced testosterone] is commentary.”

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