Afraid of falling from a great height? Maybe snakes are, too. New research shows that several species of these legless reptiles, when climbing a wrist-thick pole, grip it more tightly than strictly necessary to keep from plummeting to the ground. In lab experiments, researchers first had 10 snakes from five different species (including Morelia spilota, the carpet python, shown) slither across a flat, sensor-studded surface covered with a textured fabric to determine the force they typically used to move forward. Then, the researchers had the snakes climb a vertical, 2.4-meter-tall pole covered with the same fabric and sensors. (All snakes scaled the pole using a “concertina” movement, gripping with one section of the body while pushing or pulling other sections upward. Click here to see a video of a carpet python climbing, annotated with bars that show the pressure it exerted on the pole moment by moment.) On average, the snakes clung to the pole with at least three times more force than they actually needed to counteract gravity and move up the surface, the researchers report online today in Biology Letters. The exertion needed to generate this “safety factor,” which often exceeded five times the necessary force, requires substantial muscular effort in the short term but generally yields an evolutionary benefit to the snake because the consequences of failure (i.e., falling out of a tall tree) are so dire, the researchers say.