National Geographic : 2011 Mar
• behind the oppy ears and piebald coats and other features that characterize domesticated species. One theory among the scientists in Novosibirsk is that the genes guiding the ani- mals' behavior do so by altering chemicals in their brains. Changes to those neurochemicals, in turn, have "downstream" impacts on the ani- mals' physical appearance. For now, though, Kukekova is focused on the rst step: linking tame behavior to genes. Toward the end of every summer, she travels from Cornell to Novosibirsk to evaluate the year's newborn kits. Each researcher's interac- tion with a kit is standardized and videotaped: opening a cage, reaching a hand in, touching the fox. Later, Kukekova reviews the tapes, using ob- jective measures to quantify the foxes' postures, vocalizations, and other behaviors. ose data are layered on top of a pedigree---records that keep track of tame, aggressive, and "crossed" foxes (those with parents from each group). e joint American-Russian research team then extracts DNA from blood samples of each fox in the study and scans for stark di erences in the genomes of those that scored as aggressive or tame in the behavioral measures. In a paper in press in Behavior Genetics, the group reports nding two regions that are widely divergent in the two behavioral types and might thus harbor key domestication genes. Increasingly, it appears that domestication is driven not by a single gene but a suite of genetic changes. "Domestication," the paper concludes, "appears to be a very com- plex phenotype."