I should be on a weekly schedule starting next week, perhaps with a long-delayed post on epigenetics. Until then, here’s something that I found fascinating.
The New York Times recently tracked the progress of Dmitri Belyaev’s epic fox domestication experiment. The result:
After 40 years of the experiment, and the breeding of 45,000 foxes, a group of animals had emerged that were as tame and as eager to please as a dog.
As Belyaev had predicted, other changes appeared along with the tameness, even though they had not been selected for. The tame silver foxes had begun to show white patches on their fur, floppy ears, rolled tails and smaller skulls.
One possibility is that a handful of genes — perhaps even just one — underlie all the changes seen in domestication. A structure in the embryo of all vertebrates, known as the neural crest, is the source of cells that constitute much of the face, skull and pigment cells, and many parts of the peripheral nervous system and endocrine system. If the genes in the neural crest cells were delayed just a little in coming into action, a whole range of tissues could be affected, including the maturation of the adrenal glands that underlies the first fear response of young animals.
John Hawks raises a question about why domestication is possible at all, from the viewpoint of genetic variation:
The rats and foxes haven’t so much undergone genetic changes as simple enrichment of alleles that are already common. Which means that they may have unusual phenotypes as a result of these alleles being coincident at high frequencies, but those alleles already are doing something in normal, wild (and mostly solitary) animals. This doesn’t mean that the tame phenotype should already exist — even if all these alleles are independently common, if there are enough of them they may never all be present in any single wild individual.
So the interesting question is why these alleles that permit domestication in combination should already be common.
Domestication may involve multiple vectors, but a delay in the development of the neural crest appears to be a centrally important factor in this fox experiment. Now, given that humans have undergone some level of “self-domestication,” could we extend this result to humans? Could delaying the development of the neural crest in humans delay the whole maturation process, as is suggested by some parts of Baelyav’s fox results? And what might that mean for us today? Is there still significant genetic variation here- i.e. are some individuals or groups of people more “genetically domesticated” than others?
Mycomplete speculation here is that a high concentration of these genes selected for in domestication might result in a prolonged childhood and adolescence and lead to the existence of geeks (and perhaps a certain sort of intellectual in general). Geeks seem to hit their peak later in life and are often described as relatively non-aggressive, eager to please, late bloomers, lifelong learners, and even eternal kids (though they don’t seem to have floppy ears or rolled tails!).
Anyway, this story- and the research that comes from it- will be something worth watching.