In terms of evolution, there has to be a reason for barking, or it probably wouldn't be there.
从进化的角度而言，狗汪汪叫肯定是有理由的，要不这叫声肯定在漫长的进化过程中给淘汰掉了。
Is it to warn of predators?
那么这叫声是为了警告捕食者么？
But dogs bark when there are no predators around.
但是周围没有捕食者的时候狗也会汪汪叫。
Is it play?
那么它只是在玩耍吗？
Some dogs play without barking.
有些狗玩的时候也没有发出叫声。
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.
事实上，研究狗类行为的专家告诉我们，狗的叫声并没有固定的形式。它只是是一种多用途的响声。
Now here's another fascinating thing: adult wolves don't bark.
另一件让人着迷的事情是：成年的狼并不会吠叫。
They growl, and they whine, but no barking.
它们只是嚎叫、哀鸣，但并不吠叫。
And dogs evolved from wolves.
但是狗是从狼进化而来的。
So where did the bark come in?
那么，狗的这种吠叫声是从何而来的呢？
Mark Feinstein and Ray Coppinger of Hampshire College in Massachusetts have a theory.
对此，来自马萨诸塞州罕布什尔学院的马克?范斯坦和雷?科平杰提出了一种理论。
These biologists have noted that while adult wolves don't bark, adolescents do.
这两位生物学家注意到，虽然成年的狼不会吠叫，但是狼崽会。
Wolf pup barking seems to be an intermediate noise you grow out of.
狼崽的吠声就好比是在它成长发声过程中的一个中间产物。
