The biologists noted that they don’t believe NYC’s white-footed mice are subsisting on pizza, fries, and cheeseburgers alone—like their country cousins, these mice are probably also gathering fruits and nuts in city parks. But the scientists do think this is an example of the “cheeseburger hypothesis,” which posits that urbanized animals boost caloric intake with human food waste, most notably fast-food remains. More extensive study is needed to better understand how urbanization is transforming city mice, but it certainly seems Aesop was onto something.

📬 Sign up for the Daily Brief

Our free, fast, and fun briefing on the global economy, delivered every weekday morning.