The cabbage butterfly, voracious as a caterpillar, is every gardener’s menace. Turns out, these lovely white or sulfur yellow butterflies started trying to take over the planet millions of years before humans ever set foot on it.

 

To respond, plants threw resources into self-defense. Proto-broccoli and other brassicas got more bitter. Yet even as plants changed to deter chomping larvae, the Pieridae family butterflies were one of few insect groups that evolved to tolerate these new chemical defenses. Research from biologists at Washington University in St. Louis uses statistical methods to trace the path of ancient pierid butterflies as they diversified and their plant hosts fought back over and over again, a battle repeated across evolutionary history.