One of the most consistent uses of dogs has been in the management and herding of livestock. Even in countries where dogs are considered unclean or despised for religious reasons, people still recognize that dogs serve an important purpose as shepherds' assistants. While some dogs, like the puli or komondor, are basically guard dogs who stay with the flock to protect it from predators, the most widespread use of herding dogs is to keep flocks of sheep, geese, or cattle together.

Dogs have inherited their herding ability from wolves that hunt in packs. The coordinated activity of the pack involves keeping a group of potential prey animals together, driving them to a specific location, and then cutting out the single animal that will be the target for the kill.

These hunting behaviors are themselves based on five genetically programmed instructions. The first two have to do with positioning around the designated prey: Number one says that once the quarry is sighted, each wolf will approach the prey to approximately the same distance. Number two says that each wolf will remain equidistant from the hunting mates on its right and left. The implementation of these instructions results in the apparently elegant and complex pattern of encirclement, with the pack forming an almost perfect circle that closes steadily during the hunt.

How does a single sheepdog carry out the genetic instructions intended to guide the movements of an entire pack? From puppyhood on, a sheepdog will stalk and try to herd anything that moves. I have been told of such dogs spontaneously herding not only lambs but also chicks and even children. One person told me that her border collie attempted to herd some insects crawling across her driveway. Another told me that her Shetland sheepdog tried to herd the ripples in a puddle of rainwater.

All such herding represents the attempt to fulfill the first two genetic instructions concerning encirclement during the hunt. The problem for an animal on its own is that it will try to do the work of a dozen wolves, performing the entire pattern as if it were every member of the pack. First it decides on the proper distance that the pack should be from the flock. Next it dashes around to occupy the stations that normally would be filled by its packmates.

As it goes from station to station, playing the role of each of its missing hunting companions in turn, it encircles the flock in a wide casting motion. This curving outrun, with pauses at each outpost where another wolf should be, drives the sheep on the outer fringes to the center of the circle and thus keeps the flock together.