人类为什么会有不同的血型?

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Kasey on Why Tell me Why. Someone asked why veins are blue and blood is red. So that's part of this question: why do we have different blood types?

"Blood types are inherited, just like you inherit your eye color, or your hair texture, so you get a gene from each parent, and that determines what the child's blood type is gonna be."

血型是从父母那里继承而来。你的基因决定了你是什么血型。

There's sort for blood types?

"There is, there is A, type A, type B, type AB, and type O. The only difference is what sugar molecule is added to that point. So they are actually kind of generate from each other.

血型分为A型 ，B型，AB型和O型。血型的唯一不同就是其中的抗原分子不同。

So for you to have O, both of your parents must be O. An O can contribute an O.

如果你是O型血，你的父母都应该是O型血。也有可能其中一个是O型。

But, if, for example, your father was A and your mother was O, he could actually, one of his parents might have also been O, so he can contribute either an A gene or an O gene, that you could be O, cause you get an O from him and from your mother, while your sister might be an A.

There are some studies that show that the reason that A, B, O and AB have been distributed the way they were was because of forces that they think of primarily connected to the organism that causes malaria. It turned out to be that people who had type O were actually able to survive an attack of malaria. It appeared that malaria organism was more readily able to attach to red cells that were type A or type B, and actually kill those patients before they have a chance to reproduce.

Those people who had type O actually would get sick, but wouldn't die, and had an opportunity to reproduce, and that's how the gene goes forward.

那些O型血的人真的会得病，但不会病死，而且还有机会传宗接代。于是O型血的基因就这样代代相传下来。

And then, if you look at a map of where malaria is now and where the different peoples are, you can see that the type O was followed, there is where there's malaria, A and B has gone to colder climates where malaria wasn't a problem, and then AB was just, you know, combination of the races."