Despite the biological diversity we can see during a simple stroll in the park, for the first three billion years of life on Earth, things weren’t all that diverse. It was only about half a billion years ago that something happened — though scientists still lack a satisfying explanation for why biodiversity exists. Ashley Teufel, an incoming Omidyar Postdoctoral Fellow who is joining SFI from the University of Texas at Austin, has a hunch about what that something might be. Building on the second law of thermodynamics — the idea that entropy, or disorder, cannot decrease over time — Teufel theorizes that, once at a certain level of complexity is attained, irreversible changes will spur on further changes. Biologists call this entrenchment. “I think of myself as a computational, molecular, evolutionary biologist,” says Teufel, who completed her postdoctoral work in molecular biology at the University of Wyoming. “That means I make mathematical models on computers of evolution.” So far, Teufel’s work has focused on evolution at the metabolic level — proteins, metabolic pathways, and gene duplicates . While at SFI, she plans to extend her research to other complex systems. “A very long time ago I used to be an ecologist,” she explains. “If my findings apply in molecular biology, why wouldn’t they apply to other complex systems? I’d love to get back to my roots as an ecologist.” Teufel will arrive in the fall of 2018.