It's early emerging as we saw in those clips.

我们刚在剪辑中看到笑很早就出现了
So, what's it for? What does it do?

这说明了什么笑又有什么作用呢
If it's an accident, what's it an accident from? What properties does it have?

如果是个意外又是什么引起这意外的呢它有什么性质呢
And there are some properties that are important to know.

有几个笑的重要性质我们需要了解
It's social and communicative. Why do we know that? Because it's loud.

就是社会性和交际性我们从何得知的因为它很大声
Laughter is not like hunger. Hunger can be silent.

笑不像饥饿饥饿是无声的
Hunger is not essentially a message to other people

饥饿本来就不是要传递给他人的信息
but when humans – when it involves a loud noise –

但人类发出很大的声音
the reason why we've evolved loud noises is to communicate with other people.

为什么我们要进化出很大声音是因为我们要跟他人交流
Laughter could be viewed as a form of involuntary noisemaking

笑可以看作是一种无意识地发出声音的行为
and it's contagious. That's another interesting thing about it.

还具有感染性这是关于笑的另一个有趣性质
One of the great discoveries in television and movies

电视和电影里最伟大的发现之一就是