Scientists since Darwin have been intrigued by the simultaneous alteration of multiple morphological, physiological and behavioural traits across a wide range of domesticated animals, such as horses, pigs and dogs. For instance, reduced brain size, floppy ears, increased docility and hormonal changes are commonly seen in domesticated animals but not their wild ancestors. This phenomenon is known as the domestication syndrome, and the traits within this syndrome are assumed to change together in a correlated fashion during domestication. But surprisingly, whether or not any of these traits are in fact correlated has never been formally tested.
* This article was originally published here
