Many scientists once thought fingerprints help us hold onto objects. From an evolutionary perspective, getting a better grip on tools or weapons would have made life easier for early humans. In 2009, Dr. Roland Ennos of Manchester University designed an experiment that tested the gripping power of our fingerprints. He used a machine equipped with weights to pull strips of Perspex, a kind of acrylic, across a subject’s fingertips. The machine measured the amount of friction created as the acrylic passed over the tip. In the real world, a high amount of friction between two solid objects in contact with each other would indicate a better grip. In the experiment, the fingertips created some friction on the acrylic, but not as much as Ennos had expected. Ennos compares our fingerprints to the tires on a race car. Ridges in the tire reduce the surface area of the tire in contact with the road, which reduces friction. The ridges on fingertips have the ...