Searching for answers, researchers at Eotvos University in Budapest, Hungary, examined how dog and wolf pups interacted with humans when problem-solving. To make sure the wolf pups were well-socialized, the researchers gave them to graduate students who fed them every 4 hours and carried them in baby slings from 4 days after birth until they were able to scoot around independently. One set of experiments showed that both dogs and wolves can follow human directions, such as pointing or other gestures, to find chunks of meat hidden in containers, although the wolf pups had less success.

The difference between the canines was more apparent when the researchers made the test unsolvable by locking the food inside a container. The wolves tended to ignore their humans and tried to get to the meat themselves. The dogs, however, looked back at their masters sooner and longer, interrupting their own efforts to get the food. It's possible that by looking back at humans, dogs are more likely to enlist their help and get the meat. But the researchers say their experiments don't shed any light on the dogs' motives. The findings simply show that humans have selected canine companions that communicate like humans, says Aám Miklósi, lead author of the work, published in the 29 April issue of Current Biology.

The difference between wolves and dogs may be driven by how they pay attention, says Brian Hare, a graduate student in psychology at Harvard University. He and colleagues reported similar findings last year (Science, 22 November 2002, p. 1634). Dogs' ability to pay attention to humans' signals, Hare posits, may be a byproduct of breeding for calmer temperaments.

--NAOMI LUBICK