英語聽力文摘 狗為何會汪汪叫？

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Why Dogs Bark?

犬吠為何?

Have you ever wondered why do dogs bark?

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.

Now, a few tens of thousands of years ago, wolves and people started becoming friendly species. You can imagine a person tossing a bone to a friendly wolf from time to time. But “friendly” is the key. Nobody ever gets close to a hostile wolf. So over many thousands of years we would have been gradually selecting for certain behavioral traits–playfulness, low hostility, the ability to bond. Very puppy-like behaviors!

See what’s happening? A species that resembles a wolf puppy that never grows up may have slowly evolved in this way. That species would retain its puppy-like behaviors, such as barking, but never grow into growling, howling adult wolves. That species we would now call “dogs.”

你可曾想過犬緣何而吠呢?

從進化的角度來說，狗汪汪叫肯定是有理由的，要不這叫聲肯定在漫長的進化過程中給淘汰掉了。那么這叫聲是為了警告捕食者么?但是周圍沒有捕食者的時候狗也會汪汪叫。那么它只是在玩耍么?有些狗玩的時候也沒有發(fā)出叫聲呀。事實上，研究狗類行為的專家告訴我們，狗的叫聲并沒有固定的形式。它只是是一種多用途的響聲。

另一件讓人著迷的事情是：成年的狼并不會吠叫。它們只是嚎叫、哀鳴，但并不吠叫。但是狗是從狼進化而來的，那么，狗的這種吠叫聲是從何而來的呢?

對此，來自馬薩諸塞州罕布什爾學院的馬克·范斯坦和雷·科平杰提出了一個理論。這兩位生物學家注意到，雖然成年的狼不會吠叫，但是狼崽會。狼崽的吠聲就好比是在它成長發(fā)聲過程中的一個中間產物。(譯者注：就好比我們在學習一門新的語言時產生的中介語)

現在我們來談談人的因素，數萬年前，狼和人便開始進化成為可以友好相處的物種。你可以想象人們會時不時地向一只溫順的狼扔塊骨頭，但是“溫順”二字是關鍵，沒人會靠近一只充滿敵意的狼。因此，實際上，成千上萬年以來，人類都在漸漸地、有意識地進行著選擇，選擇具有特定行為特征的狼群。這些特征包括愛嬉戲玩鬧，溫順，合群。這些行為難道不像小狗嗎?

現在明白這是怎么回事了嗎?就像這樣，一種類似于狼崽的物種開始慢慢的進化著。這一物種保留了那些幼崽般的行為特征，比如吠叫，它們也不會進化為嚎叫的成年狼。這一物種便是我們現在把它稱之為“狗”的動物。