Why Is the Penis Shaped Like That?

To paraphrase a marketing expression, science, it not just for nerds anymore. If we want to fully understand the human condition, including our sexuality, our relationships and our desires, we need to understand science. Every month in Scientific America and Slate, Jesse Bering brings these issues to the forefront of consciousnes.  Now he takes us on a kind of grand tour evolutionary biology  in his book Why Is the Penis Shaped Like That?: And Other Reflections on Being Human. My conversation with Jesse Bering: