Get the Popular Science daily newsletter💡 Breakthroughs, discoveries, and DIY tips sent six days a week. Every week, without fail, the three-toed sloth takes a breathtaking, almost suicidal risk—all for the sake of a bowel movement. Or, to put it in terms familiar to anyone who has sat through a long Zoom meeting, a “bio-break.” With fast-moving predators lying in wait, being on or near the ground is the number one cause of mortality in sloths. And because sloths have among the slowest metabolisms ever recorded in animals , the climb down the tree and back up represents one of the biggest energy expenditures of their entire week. “It’s like if I had to go on a 5K run down the middle of an interstate, just to use the bathroom,” University of Wisconsin-Madison wildlife ecologist Dr. Jonathan Pauli tells Popular Science . “It’s really costly, and it’s really risky.” Which begs the question: Why do three-toed sloths take such risks for a poo? Why not just do the sensible thing and poop from the trees?…