Genetic Factors in Tameness of Rats

In 1959 Dmitri Belyaev, a Soviet scientist, began experiments in the pursuit to domesticate foxes. Through a series of multiple crosses only involving those foxes who displayed the least amount of timidness and the most amount of "kindness", Dmitri sought after a tame silver fox. It only took 20 generations for 35% of the experimental population to reach an "elite" level, meaning these foxes were not only tame and nonhostile, but were eager for human contact. 

Researchers at the University of Leipzig in Germany followed up these experiments by trying to understand the genetic variables involved of the tameness of animals. Using rats who's ancestors were the start of an experiment started by Dmitri over 40 years ago, researchers carried out the same process of breeding those rats most kind to researchers while also breeding those rats who were most hostile or timid in a separate group. Researchers found that after over 60 generations of breeding, mice from the two groups behaved very differently. The rats of the timid group were apt to running away or attacking upon contact with a researcher, while the rats of the "tame" group were easily handled and were comfortable in human presence. Researchers were able to identify gene regions that were responsible for tameness upon crossing these rats to produce hybrids. It was found that some gene regions contained gene variants that were more active in aggressive rats while some gene regions were more active in the tame rats. More research must be done to determine exactly what genes are in play when domesticating animals and how these genes work. Animals have been domesticated for thousands of years but the genetic factors involved in these domestication processes are still little known which is why more research like this must be done.

Article Link: http://www.sciencedaily.com/releases/2014/11/141107091658.htm
Supporting Link: http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1002962