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According to the classic theory, this is true for the red pigment as well.
根据传统理论，这对红色也适用。
It was there in the leaf all along but it was hidden by the green chlorophyll.
它一直存在于树叶中，但是被绿色的叶绿素藏起来了。
OK, so that’s the classic explanation and it’s partially right. Why do I say partially?
好了，这是传统的解释，部分是对的。为什么我说部分？
Well, it’s probably true for pigments like yellow or orange, but it doesn’t seem to hold for the red pigment.
因为这对像黄色和橘色这样的色素可能是正确的，但是似乎不适用于红色色素。
Let’s back up a bit. Just what produces this red color in leaves? It’s a red pigment called anthocyanin.
我们往回倒一点。什么产生了树叶中的红色呢？是一种叫做花青素的红色色素。
Here is where the classic explanation doesn’t seem to apply to red.
这就是传统解释似乎不适用于红色的地方。
What’s interesting is that during the summer there was very little if any anthocyanin in the leaves,
有趣的是在夏天，树叶中几乎没有花青素，
but in the weeks before a tree is about to drop its leaves, the production of anthocyanins increases significantly.
但是一棵树开始落叶前几个周，花青素开始大量增加。
In other words, unlike those other pigments, anthocyanins are not just unmasked by the breakdown of chlorophyll in autumn;
换句话说，和其他的色素不同，花青素不是因为叶绿素在秋天分解而开始显现，
they are actually created at this time.
它们实际上是那个时候才产生的。
So that raises a question, why would a tree produce more anthocyanin just before dropping its leaves?
那么这就提出了一个问题：一棵树在落叶之前为什么要制造出更多的花青素？
Why does the tree spend so much of its resources doing this just before the leaves fall off?
为什么树要在所有的树叶掉落之前花那么多资源这么做？
On the surface, that doesn’t make sense.
从表面来看这一点都说不通。
