【英语时差8,16】为何狗要咆哮（在线收听）

 In terms of evolution, there has to be a reason for barking, or it probably wouldn’t be there. Is it to warn of predators? But dogs bark when there are no predators around. Is it play? Some dogs play without barking. In fact, people who study canine behavior find there isn’t much of a pattern to barking–it seems to be an all-purpose noise. Now here’s another fascinating thing: adult wolves don’t bark. They growl, and they whine, but no barking. And dogs evolved from wolves. So where did the bark come in? Mark Feinstein and Ray Coppinger of Hampshire College in Massachusetts have a theory. These biologists have noted that while adult wolves don’t bark, adolescents do. Wolf pup barking seems to be an intermediate noise you grow out of.