Geckos have an incredible ability to stick to surfaces. Some studies suggest the over-engineered reptiles can hold hundreds of times their own body weight. In 2000, a University of California team showed that the adhesion was due to very weak intermolecular forces produced by the billions of hair-like structures, known as setae, on each gecko foot. These “Van der Waals” forces arise when unbalanced electrical charges around molecules attract one another. The cumulative attractive force of billions of setae allows geckos to scurry up walls and even hang upside down on polished glass. The reptile’s grip is only released when it peels its foot off the surface.