This article is from the WSSF 2015 AFRMA Rat & Mouse Tales news-magazine.
Did You Know? Domestication in animals
causes a change in skeletal morphology so they tend to
have a smaller and more slender skull. Studies found in
tame rats, their skulls are narrower than wild aggressive
rats. [This does not mean that narrow skulls should be
bred for. See the article
Question: Head Shape On Rats in the WSSF 2014 issue, for more on head shapes. Ed.]
Researchers also found that even though white spotting was more common in tame animals, they did not find a link between tameness and white spotting. [Fanciers have found this to be true, certain colors/markings do not mean a better temperament than another, but rather it is from selection. Ed.]
The Belyaev Rats: An interview with PhD Student Alex Cagan,
Pro-Rat-A 205 Jan./Feb. 2015. Article had a photo of a very nicely marked
Bareback rat. Study
Influences on Brain Gene Expression in Rats Selected for Tameness and Aggression
published in Genetics November 1, 2014 vol. 198 no. 3 1277-12900.