
Some of the most charismatic and recognizable features in the animal kingdom are the impressive weapons they wield when competing with each other. Porcupine quills, the chelae of crayfish, and the antlers of elk all require an enormous amount of energy dedicated primarily to fighting their fellows for resources and mates. Most species get by with a modest arsenal; mockingbirds will pick fights over the best territory, but their beaks are hardly fearsome. For centuries scientists have studied and debated the evolutionary pressures that guide the creation of extreme biological weaponry we see in mastodons, kudu, and stalk-eyed flies1. Why do a few species develop these exaggerated armaments when most get by with beaks and jaws that can crack seeds not bones?Some of the most charismatic and recognizable features in the animal kingdom are the impressive weapons they wield when competing with each other. Porcupine quills, the chelae of crayfish, and the antlers of elk all require an enormous amount of energy dedicated primarily to fighting their fellows for resources and mates. Most species get by with a modest arsenal; mockingbirds will pick fights over the best territory, but their beaks are hardly fearsome. For centuries scientists have studied and debated the evolutionary pressures that guide the creation of extreme biological weaponry we see in mastodons, kudu, and stalk-eyed flies1. Why do a few species develop these exaggerated armaments when most get by with beaks and jaws that can crack seeds not bones?