Carl Zimmer, in the NYTimes, on dogs’ evolution “From Fearsome Predator to Man’s Best Friend”:
… Dog brains… have become exquisitely tuned to our own. Scientists are now zeroing in on some of the genes that were crucial to the rewiring of dog brains…
As they reported [last week] in the journal Nature Communications, they found that the split started 32,000 years ago. Those early dogs would have encountered small bands of hunter-gatherers. People didn’t settle in villages to farm in East Asia until about 10,000 years ago.
After dogs split from wolves, their genes began to evolve in a new direction. Dr. Zhang and his colleagues were able to identify some of these evolving genes. A number of them, it turned out, are active in dog brains. (Dr. Zhang and some of his colleagues published some of these results last week in the journal Molecular Biology and Evolution.) …
The results offer some tantalizing hints about how wolves first turned doglike. “The conventional view is that the hunter-gatherers go out and get a puppy,” said Chung-I Wu of the University of Chicago, an author of the Nature Communications study. If humans actually did breed early dogs this way, then dogs would have descended from a very small population.
That’s not what Dr. Wu and his colleagues have found, though. Instead, it appears that a large population of wolves started lingering around humans — perhaps scavenging the carcasses that hunters left behind.
In this situation, aggressive wolves would have fared badly, because humans would kill them off. Mellower wolves, by contrast, would thrive. If this notion turns out to be true, it means that we didn’t domesticate wolves — they domesticated themselves. SLC6A4 may have played a crucial part in this change, because serotonin influences aggression.
To test these ideas, Dr. Zhang and his colleagues are gathering DNA from more dogs and wolves. They also hope to collaborate with cognitive scientists to see how variants of genes like SLC6A4 affect the behavior of dogs today. Their results may also help explain human evolution, because Dr. Zhang and his colleagues found that some of the same genes that evolved in dog brains, such as SLC6A4, also experienced natural selection in human brains.
“Humans have had to tame themselves,” said Adam Boyko of Cornell University, one of Dr. Zhang’s collaborators on the Molecular Biology and Evolution study. “The process is probably similar to dogs — you have to tolerate the presence of others.”
Progressively cooperative or not, what’s on the agenda for the start of the weekend?