The hip nudge functions as a pacifying behavior. It signals friendliness. By turning its back to us, the dog shows it doesn’t intend to attack—it directs its teeth away from us. It also shows it trusts us.

Dogs use a variety of this same behavior during mating rituals when the male nudges the female.

I described this behavior first time in 1987 in the original edition of “Dog Language,” after having spent several years observing, photographing and filming dogs (Canis lupus familiaris), wolves (Canis lupus lupus) and foxes (Vulpes vulpes).

There are only small differences between wolf and dog, which we can describe as dialects. The fox is different because, although displaying many behaviors common to the other two, it is not as social as its cousins.