Beth Shapiro

So when I talk about and I call this fossil a name, you and I know that we're having the same conversation.

Right.

If I am in charge of delineating species because I'm trying to figure out which agency is going to care for this endangered species, I might use geography to figure out what one species is and what another species is.

The species concept that we learn when we take our introductory biology course is a species concept that was developed in the middle part of the 20th century called the biological species concept, which says you're a species if you can breed and if your offspring are fertile.

But we know that lots of things violate that.

Brown bears and polar bears.

We just talked about how they're hybrids.

Humans and Neanderthals violate that.

Cattle and bison violate that to a way less of an extent than we thought that they did.

This is actually a cool story.

Do you know what a beefalo is?

No, a beefalo is a breed of hybrid that is five-eighths cattle and three-eighths bison that supposedly has better meat.

Yes, it was one of these breeds that they tried to make.

Turns out it barely works at all.

No, they just lied.

So I've spent a lot of time being interested in this sort of admixture history.

And so I was interested in brown bears and polar bears and humans and Neanderthals.

And what is it that suddenly makes a species?

not able to breed with another species?

What is it that causes that sort of last wall to go up and then suddenly you're the biological species?