Now, a few tens of thousands of years ago, wolves and people started becoming friendly species.
时至今日，数万年前，狼和人便慢慢演变成进化成为可以友好相处。
You can imagine a person tossing a bone to a friendly wolf from time to time.
你可以想象人们会时不时地向一只温顺的狼扔块骨头。
But “friendly” is the key.
但是“温顺”一词至关重要。
Nobody ever gets close to a hostile wolf.
没人会靠近一只充满敌意的狼。
So over many thousands of years we would have been gradually selecting for certain behavioral traits-playfulness, low hostility, the ability to bond.
因此，实际上，成千上万年以来，人类都在渐渐地、有意识地进行着选择，选择具有特定行为特征的狼群。这些特征包括爱嬉戏玩闹，温顺，合群。
Very puppy-like behaviors! See what's happening?
这些行为难道不像小狗吗？
A species that resembles a wolf puppy that never grows up may have slowly evolved in this way.
现在明白这是怎么回事了吗？就像这样，一种类似于狼崽的物种开始慢慢的进化着。
That species would retain its puppy-like behaviors, such as barking, but never grow into growling, howling adult wolves.
这一物种保留了那些幼崽般的行为特征，比如吠叫，它们也不会进化为嚎叫的成年狼。
That species We would now call that species “dogs.”
这一物种便是我们现在把它称之为“狗”的动物。
