【英语时差8,16】牧羊犬和狼（在线收听）

 Sheepdogs and Wolves If you ever see a sheepdog at work, you might be amazed at how well suited its actions are to the very human concern of keeping a flock of sheep together. What’s more amazing, much of a sheepdog’s behavior doesn’t have to be trained, but is already present as a complex set of sheep herding instincts. A scientist who studies ethology, or animal behavior, might ask how prehistoric shepherds first coaxed such useful behavior from their domesticated wolves, the ancestors of today’s sheepdogs. As a matter of fact, a sheepdog’s herding instinct isn’t so different from the natural hunting instincts that all wolves share. For example, when a pack of wolves hunts a herd of caribou, they begin by circling their prey, crouching low if the caribou become too alarmed. Occasionally, if a caribou bolts, a wolf will jump up and nip at its neck, steering it back toward the herd. These hunting instincts help gather the prey together, making it easier to bring them down when the pack leader jumps in for the kill. Early shepherds took advantage of these wolf instincts when training their domesticated dogs. The dogs viewed the shepherd as their pack leader, and they controlled the flock of sheep the same way their wolf cousins would control a herd of caribou in the wild always steering the flock toward the shepherd. Indeed, it’s difficult to persuade modern sheepdogs to steer their flock in any other direction. The wild instinct of directing prey toward the pack leader is still too strong. Centuries of selective breeding have refined these instincts to a considerable degree, but the foundation of a sheepdog’s behavior comes from the wild.