blood was/is divided into four types

[diamondcutter]

Blood Types
Until the early twentieth century, attempts to transfuse blood from one person to another were usually unsuccessful. Then, in 1901, an Austrian scientist discovered that blood was divided into four types. These four blood types were named A, B, AB, and O. Blood type O is the most common around the world. Blood type A is the second most common, and type AB is the least common. If people with type A blood are given type B blood, or people with type B blood are given type A blood, they will probably die.
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Source: Reading Advantage 1, Cengage Learning

Then, in 1901, an Austrian scientist discovered that blood was divided into four types.

In the sentence above, as that blood has four types is a fact, I think we can also use the present simple tense to rewrite “blood was divided into four types” like this:
...blood is divided into four types.
What do you say?

 

[5jj]

I agree.

 

[Tdol]

Or something like that there are four types of blood.

 

[diamondcutter]

What about this?
Blood has four types.

 

[5jj]

That doesn't work.

 

[jutfrank]

If I were being very picky (which I'm not), I might say that both was divided and is divided are wrong.

It is not a fact that was discovered. It's just that it made (and still makes) very good sense for medical professionals to classify blood into these types. Nature doesn't do any dividing—it is people who do that. I think the thought is much better expressed like this:

Then, in 1901, an Austrian scientist discovered that blood could be divided into four types.

 

[probus]

As a very minor footnote, the passage is factually incorrect. At first, blood was divided into types A, B and zero. The zero was intended to mean "no type", but because A and B are letters people read the zero as O. Type AB, the rarest, was not identified until years later.