Prum is an ornithologist at Yale, here is the audio, video, and transcript. Here is part of the summary:
Richard joined Tyler to discuss the infidelity of Australian birds, the debate on the origins of avian flight, how the lack of a penis explains why birds are so beautiful, why albatrosses can afford to take so many years to develop before mating, the game theory of ornithology, how flowers advertise themselves like a can of Coke, how modern technology is revolutionizing bird watching, why he’s pro-bird feeders yet anti- outdoor cats, how scarcity predicts territoriality in birds, his favorite bird artist, how Oilbirds got their name, how falcons and cormorants hunt and fish with humans, whether birds exhibit a G factor, why birds have regional accents, whether puffins will perish, why he’s not excited about the idea of trying to bring back passenger pigeons, the “dumb question” that marks a talented perspective ornithologist, and more.
Here is one excerpt:
COWEN: Putting path dependence aside, if you were trying to give us the most fundamental explanation of why sexual dimorphism is different in birds compared to mammals, what would that be?
PRUM: Well, that’s actually a really big question. [laughs]
COWEN: Of course, but the most fundamental factor — what is it?
PRUM: The most fundamental factor is that most birds don’t have a penis.
COWEN: Talk me through the equilibrium there.
PRUM: [laughs] There’s a lot. That’s where we start: Most birds don’t have a penis, which means that one of the things that happens in avian evolution that’s distinct from mammals is that the kids require a lot of care. They’re growing up in the nest, they’re hatching out of an egg, but they’re very, very vulnerable until they can fly.
Birds have a very rapid period of rapid development. That means that they grow up and leave the nest, and you need two parents to do that efficiently in most diets or most kinds of ecologies. That means the dad’s got to be at the nest.
We usually thought that you have social monogamy, at least two birds helping raise the young, because the young are so needy and they have to grow up quickly. But there’s another possibility, which is that they could evolve to be so needy and grow up quickly because they managed to get males at the nest.
One of the things that happened in the phylogeny of birds — you’ve got ostriches and their relatives, and you’ve got chickens and ducks, and then you’ve got the rest of birds, and that’s a bunch. That’s the vast majority of them, and in that lineage leading to the rest of birds, the penis evolved away, and the question is why. My own theory is that female birds preferred mates that did not have a penis.
One of the ancillary benefits of that, one of the correlated benefits of that is that they were no longer subject to sexual coercion or sexual violence. They could be coerced behaviorally, but they couldn’t be forcibly fertilized. That means that they have freedom of choice, and what do they do with their freedom of choice? They choose beauty. One of the reasons why birds are so beautiful is that males don’t have a penis. They have to be subject to choice in order to effect reproduction, and also they have to invest if females require it.
COWEN: Now, sometimes albatrosses don’t breed until they’re 20 years old or even, on average, maybe it’s what — 10 years old. What are they doing in the meantime that’s so important?
PRUM: Well, that is a deep question.
Recommended, this was one of my favorite CWT episodes.