The Spiciest Ideas Of Evolutionary Biology - Dr Jerry Coyne - #960

**Chris Williamson** (0:00)
How do you describe the central thread of your work over the years?

**Jerry Coyne** (0:06)
Well, I'm retired now, so the thread has sort of changed direction. But when I was a scientist, I call myself a superannuated scientist now. But when I was working in the lab, I worked on the problem of speciation, or the origin of species, which is of course the title of Darwin's 1859 book. And it's a problem that Darwin didn't solve. That's why I took it up when I was a graduate student. I think we know a lot more now. We certainly, Darwin knew almost nothing about speciation. So to call his book the origin of species is a bit of a misnomer. He could call it the origin of adaptations, which might be a natural selection. But in terms of species, that is the lumpiness of nature. The fact that creatures are not a spectrum, but they're discreet, more or less discreet entities. That's the problem that Darwin did to solve. That's the problem I was working on.

**Chris Williamson** (1:04)
Right. What's the layman's description of speciation?

**Jerry Coyne** (1:08)
Well, are you talking about how it happens or how I define it?

**Chris Williamson** (1:13)
Give us both.

**Jerry Coyne** (1:14)
Well, the definition is simply the speciation is the origin of species. If you look at nature, as I said, you don't find that it's a continuum. All the way from bacteria to humans, but that's not a hierarchy. That's just what people perceive as a hierarchy. It's lumpy. So if you look at a bird out your window, you're going to know what it is instantly. You're not going to say, I don't know. It looks like a half black bird and a half Robin or whatever. No, they come in pretty discrete packages, and that is the problem of speciation. What on earth would make a continuous evolutionary process give rise to entities that are absolutely discontinuous?
That's really the problem of the origin of species. Right. Darwin made almost no end roads whatsoever.

**Chris Williamson** (2:07)
Why was it a difficult circle to square for him?

**Jerry Coyne** (2:10)
Well, because in order to attack the problem with speciation, you have to know what species are. Although we say nature is lumpy and these lumps are species, that's not really the problem. The question is, well, why do we get those lumps? And it was in about the 1930s that people realized that those lumps are kept separate by what we call reproductive isolated barriers. That is, barriers that keep the genes from one species from mixing with those of another species. For example, those barriers could be that the hybrids are sterile or inviolable. So even if they make, you don't get any intermixing or they couldn't like each other. I mean, like a lion and a tiger, they'll mate in the zoo and produce things like ligers or tiglons, which they'll have. But when they co-occur or where they used to co-occur, and say the Gere forest of India, they don't interbreed. And in nature, there's a lot of animals that just simply don't like the way they look. They don't like the mating behavior of the species. They don't like the pheromones of the other species.
Or in the case of plants, they produce pollen and eggs at different times. That's called temporal isolation. So there's all these barriers that keep numbers of different species apart. Now that immediately raises the problem that you want to solve, which is how do these barriers come about to keep species separate in a continuous evolutionary process. So that's what I was working on.

**Chris Williamson** (3:45)
I guess the Batman to your Bruce Wayne of work over the years has been advocating for evolutionary views, advocating for the evolutionary method overall, that this is something that is true and that people should believe in pushing back against anti-evolutionary positions. Is that a fair assessment?

**Jerry Coyne** (4:06)
Yeah, I spent a lot of my time, particularly when I was younger, arguing against creationists and creationism. Finally, it resulted in me having to write a book about it called Why Evolution Is True. Because when I taught my first evolution course, which was probably in about 1983, back in the place to see, the first thing any professor does when he or she writes a course is to say, well, you pick up the textbook that's relevant to the course, and you see how it's organized, and you get ideas about how to write a course. Well, when I did that for evolution, I looked at the evolution textbooks, and none of them had anything about the evidence for evolution in them. They just assumed that you assume that evolution was true, and then you go into things like population, genetics, and species, etc. But they left behind all the stuff that was so prominent in the textbooks of the 20s and 30s, why biologists believe evolution is true, and why it is a scientific fact, as we call it, provisional truth, and not just a mere speculation.