 Sheep were among the first animals to be domesticated by mankind ( although the domestication of dogs may be over 20 @,@ 000 years earlier ) ; the domestication date is estimated to fall between 11 @,@ 000 and 9 @,@ 000 B.C in Mesopotamia . Their wild relatives have several characteristics , such as a relative lack of aggression , a manageable size , early sexual maturity , a social nature , and high reproduction rates , which made them particularly suitable for domestication . Today , Ovis aries is an entirely domesticated animal that is largely dependent on man for its health and survival . Feral sheep do exist , but exclusively in areas devoid of large predators ( usually islands ) and not on the scale of feral horses , goats , pigs , or dogs , although some feral populations have remained isolated long enough to be recognized as distinct breeds . 
