As with juvenile wolves or coyotes, adult livestock conducting dogs displayed the first-half segment of a functional predatory system of motor patterns and did not express play or social bonding toward sheep; whereas, like wolf or coyote pups, adult livestock protecting dogs displayed sequences of mixed social, submissive, play and investigatory motor patterns and rarely expressed during ontogeny (even when fully adult) predatory behaviors. The most parsimonious explanation of our findings is that behavioral differences in the two types of livestock dogs are a case of selected differential retardation (neoteny) of ancestral motor pattern development.