During domestication, dogs most probably have been selected for increased tractability (meant as controllability or ease in handling). If so, then considerable differences should be found between domestic dogs and their closest wild relatives, wolves, in this trait. To reveal if such a difference exists, researchers at the Family Dog Project, Eötvös Loránd University assessed the development of tractability in hand-raised wolves and similarly raised, 3-to-24-week-old dogs during fetching, calling, obeying sit signal, hair brushing and walking in a muzzle. They found that despite intensive socialization, wolves remained less tractable than dogs, especially in contexts involving access to a resource. Dogs also appeared to be more prepared to follow human initiation of action than wolves. Based on these results they suggest that tractability is indeed a major factor in the making of 'man's best friend.'