Jessica's daughter, Isabelle, has Williams syndrome, a genetic disorder with a number of symptoms. Children with Williams are often physically small and frequently have developmental delays. But also, kids and adults with Williams love people, and they are literally pathologically trusting. They have no social fear. Researchers theorize that this is probably because of a problem in their limbic system, the part of the brain that regulates emotion. There appears to be a disregulation in one of the chemicals (oxytocin) that signals when to trust and when to distrust. . . ."Self-Domestication" is a theory about why we are different from our Paleolithic ancestors. Those differences include: our heads are less massive and bony, our faces are smaller, our teeth are less robust. There are three main theories about how this happened. Some people say it was climate change at the end of the Ice Age, others changes in diet related to the origin of agriculture and a general increase in plant foods, but right now the hottest idea is self-domestication. The idea comes from the Belyaev Fox Experiment, in which Russian biologist Dmitry Belyaev showed that he could produce all the changes that we see in domesticated animals (shorter faces, floppy ears, spotted coats, etc.) by breeding for one trait, the willingness to be approached and touched by humans.
When Isabelle was younger, she was chronically happy. She smiled at anything. She loved everyone: family, friends, strangers. She reached for them all, and, in return, everyone loved her. Strangers would stop Jessica to tell about how adorably loving Isabelle was.
But as Isabelle got older, the negative side of her trusting nature began to play a larger role. A typical example happened a couple of years ago, when Jessica and her family were spending the day at the beach. Isabelle had been begging Jessica to go to Dairy Queen, and Jessica had been putting her off. Then Isabelle overheard a lady just down the beach.
"She was telling her kids, 'OK, let's go to the Dairy Queen,' " Jessica says. "And so Isabelle went over and got into the lady's van, got in the back seat, buckled up and was waiting to be taken to Dairy Queen with that family."
Jessica had no idea what had happened to Isabelle and was frantically searching for her when the driver of the van approached her and explained that she had been starting her car when she looked up and saw Isabelle's face in the rearview mirror.
The woman, Jessica says, was incredibly angry.
"She said, 'I am a stranger, you know!' " Jessica says. Essentially, the woman blamed Jessica for not keeping closer watch on her daughter -- for neglecting to teach her the importance of not getting into a car with someone she didn’t know. But the reality could not be more different. "It's like, 'My friend, you have no idea,' " Jessica says.
The differences between us and Paleolithic humans closely parallel those between dogs and wolves; this can be shown mathematically using skull measurement ratios and so on.
Now comes genetic evidence that the genes implicated in Williams Syndrome may also be involved in the changes that make us "anatomically fully modern humans," and that Williams Syndrome can be seen as a sort of "hyper domestication." These are technical articles in genetics, but if you are really curious see here, here, and here.
Besides being trusting, many Williams Syndrome sufferers are retarded, and I've never heard of one being a genius. So if self-domestication is mild Williams Syndrome, does that mean we have gotten less intelligent? It seems possible. Our heads have gotten smaller, and brain size is correlated with intelligence, albeit weakly. Many domesticated animals are stupider than their wild cousins, including cows and horses. But it isn't always true; domestic pigs are still pretty smart and when they go wild they do perfectly fine, even outcompeting truly wild pigs. Border collies are in some ways much smarter than wolves, for example in their ability to understand human language. And this points to one of the more positive findings of this research: the same genetic changes that make us more like Williams Syndrome kids may have increased our linguistic ability.
And even if we have gotten individually a little less smart, that is of course a lot less important than our increased ability to pool our mental resources.
I don't know how seriously to take this. Williams Syndrome has lots of symptoms, some of which are physical, for example weaker hearts and shorter life expectancies. Just because the same genes are involved doesn't mean the processes are really that similar. This research is very new and experimental, flagged as such in the journals.
But this is just so suggestive that I can't resist passing it on. It provides another way to think about how we have changed and are changing and opens up all sorts of questions.