Tameness is in the genes

COLD SPRING HARBOR, N.Y. — Taming animals makes an impression on their DNA.

Domesticated animals tend to have genetic variants that affect similar biological processes, such as brain and facial development and fur coloration. Alex Cagan of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, reported the results May 6 at the Biology of Genomes conference.

Cagan and colleagues examined DNA in Norway rats (Rattus norvegicus) that had been bred for 70 generations to be either tame or aggressive toward humans. Docility was associated with genetic changes in 1,880 genes in the rats. American minks (Neovison vison) bred for tameness over 15 generations had tameness-associated variants in 525 genes, including 82 that were also changed in the rats.

The researchers also compared other domesticated animals, including dogs, cats, pigs and rabbits, with their wild counterparts. The domestic species and the minks had tameness-associated changes in genes for epidermal growth factor and associated proteins that stimulate growth of cells. Those proteins are important for the movement of neural crest cells within an embryo.

That finding seems to support a recent hypothesis that changes in neural crest cells could be responsible for domestication syndrome, physical traits, including floppy ears, spotted coats and juvenile faces, which accompany tameness in many domestic animals.