When you observe nature, especially living things, does what you see look purposeful or messy? In other words, do living things have body parts that look like they have a proper fit and function, or do they seem as though they were cobbled together through some kind of tinkering process?

“Casey at the Bat” is one of America’s best-known poems. Surprisingly, even operas have dramatized the story of Mudville Nine’s baseball slugger. In Ernest Thayer’s 1888 poem, a smugly overconfident Casey was ready to wallop a game-winning home run, only to dash the hopes of Mudville by totally whiffing the ball with a massive—and embarrassing—swing-and-a-miss.