Did you know that animal penises come in a wide variety and that some animals have bones in their penises? In this episode, Laura talks with biologists Dave Hosken and Matt Dean about the wide variety of penises found in different animal species. We discuss some of our favorite examples and then explore hypotheses for why such variation evolved. Matt shares his lab's research findings on the evolution, function, and development of the penis bone (a.k.a., the baculum).