In this new short, a tree full of blood-sucking bats lends a startling twist to our understanding of altruism and natural selection.

In our recent episode The Good Show, we grappled with a troubling question: how can goodness and self-sacrifice thrive in a world that Darwin tells us ought to favor selfishness? We follow up on that idea with Jerry Wilkinson, chair of biology at the University of Maryland-College Park, who describes an amazing discovery he made in 1977 that revealed an entirely new way of explaining selflessness.