Those with the mutation produce lactase throughout their lives.

有这个突变基因的人一生都可以生成出乳糖酶。

And for most of history, humans stopped producing lactase after childhood.

从人类的发展上看，大多数情况下，人类过了儿童时期就不会再生成乳糖酶了。

But the older we grow, the fewer lactase enzymes our body produces.

但是，随着年龄的增长，人体产生的乳糖酶越少。

This adaptation has to do with a specialized enzyme: lactase.

乳糖酶。

And the lactase that so many of us don't have, is one of these.

我们很多人所缺乏的乳糖酶就是其中之一。

And those bacteria possess about 1000 different kinds of enzymes of their own, including lactase.

这些细菌拥有大约 1000 种自己的酶，包括乳糖酶。

An enzyme specifically created by the body for this purpose and named for what it breaks down——Lactase.

一种专门由人体为此而产生的酶，并以它所分解的物质命名——乳糖酶。

That one exception is humans, but like every other mammal, will still hardwired to stop producing lactase after infancy.

人类是个例外，但就像其他哺乳动物一样，在婴儿期后仍会停止分泌乳汁。

This so-called lactase persistence trait probably spread as Neolithic groups trekked north and west through Europe.

这种所谓的乳糖酶持久性特征可能随着新石器时代的群体在欧洲向北和向西跋涉而传播。

I never go anywhere without my Lactaid, fast acting lactase enzyme.

- 如果没有我的 Lactaid，速效乳糖酶，我绝不会去任何地方。