This is Science Friday. I'm Ira Flato. Birds do it, bees do it, even bacteria do it. I bet you weren't expecting that. I'm talking about going extinct, kicking the bucket, becoming an ex-species. Up till now, research on bacterial history has been difficult because bacteria do not fossilize well. And you would think bacteria,

which conquered the globe long before we arrived, could encounter any new hardship they, well,

they could eventually adapt to it if they got in trouble. But according to a new model

based on modern bacterial relationships and some advanced math, death comes even for the

smallest, at a rate that claims nearly as many species as are generated.

In other words, most of the bacterial lineages that have ever existed, most of them are already

extinct.

Here to explain how we know that is Stylianus, Luca, a postdoctoral

fellow in zoology, University of British Columbia Center for Biological Diversity in Vancouver.

He joins us by Skype. Welcome to Science Friday.

Hello, Ira. Hey there. So how do you investigate the history of bacteria without using fossils?

Well, the only thing that's pretty much left is to look at the bacteria that exists today,

because that's the only thing we have.

So we looked at phylogenetic trees.

Those are mathematical structures that encode in a very formalized way the evolutionary relationships

between bacteria living today.

And so by looking at these relationships with some sophisticated math over time, we can say something

about how evolution generated but also

destroyed lineages over time.

So your model found that bacteria go extinct almost at the same rate as they speciate, but in general,

are getting more diverse? Is this surprising?

Well, if you consider it in the whole context of what we know about life, in particular, plants and animals, where we know much more about their diversification, it's actually in line with

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