The purpose of fingerprints

Published 6 April 2009

All wrinkles on our bodies are the result of bending and stretching of the skin — except fingerprints, which are not the result of repeated motion; scientists speculate that fingerprints are there to enhance tactile sensation — although science cannot yet come up with the reason why all of us have a unique set of prints

Most wrinkles on our bodies appear as a result of bending and stretching of the skin — except fingerprints, which are not the result of repeated motion. Each of us is born with a unique set of them, although scientists are not quite sure what purpose fingerprints serve.

One possible purpose of fingerprints is that they improve our sense of touch. In a recent study, scientists have investigated this idea by performing a series of experiments with artificial fingertips made of rubber-like sensors. The scientists compared the sensitivity between these grooved artificial fingertips and a smooth skin-like material, and found that the grooved fingertips produced vibrations up to 100 times stronger than the smooth material when sliding against a slightly rough surface. The researchers, from the Ecole Normale Superieure in Paris, explained that increased vibrations give us an enhanced sense of touch, especially for detecting textures. As you rub your fingers across a textured surface, your fingerprints specifically amplify vibrations in an optimized frequency range to stimulate the Pacinian corpuscles, which are nerve endings in the skin that detect textures. In turn, texture information allows us to identify objects by touch.

As the finding demonstrates, not only does our nervous system (the “software”) play a role in tactile computation, but the physical characteristics of the body (the “hardware”) also enhance the computation when sensing. The research, however, does not explain why everyone’s fingerprints are unique, or why our fingerprints are typically arranged in elliptical swirls. The scientists suggest that the loop design may ensure that some ridges are always brushing perpendicular to a surface, no matter the orientation of the fingertips. In addition, the researchers predict that this work could lead to enhanced tactile feedback for prosthetic hands.

-read more in  J. Scheibert et al., “The Role of Fingerprints in the Coding of Tactile Information Probed with a Biomimetic Sensor” Science 323. no. 5920 (13 March 2009): 1503-06 (DOI: 10.1126/science.1166467) (sub. req.)