However, a new scientific study has shown that the skin under our very fingernails is so highly-tuned to be touched, that we are able to locate touch down to just a single finger. The discovery goes some way to explaining the evolutionary function of our nails and provides clues as to why the human hand is so capable.
The Secret Sense of the Nail
Humans Nails Are Not Just A Dead Layer Of Cells The response stays confined just right below the top layer thanks to a incredibly subtle array of receptors which can perceive even the slightest pressure and vibration.
For the study, University of London psychologist Matthew Longo recruited 38 volunteers to feel the precision with which their fingernails could locate. The participants were told to indicate the exact position on how far their nails were touched when they are being tapped by a stick, or when a thin filament is drawn along it´s length.
The results were striking: the volunteers had an uncannily accurate tactile sense – they could say exactly where we were applying the stimulation. According to Longo, this sensitivity is due to the fact that our bodies are equipped with a type of specialized mechanoreceptors called Pacinian corpuscles that lie beneath the skin just below our nails.
Those Pacinian corpuscles are the same receptors that blind people use to feel their surroundings while they hold a cane. Such oddities suggest that our own big brains are weirdly tuned to detect even the faintest vibrations, which must have been important for some early mammal ancestors.
The Role Nails Play in Evolution
The high sensitivity of the fingernail invites questions about what evolutionary advantage such skill might have conferred.
Our primate relatives have claws, while humans evolved the far less robust fingernail. Scientists have long been puzzled by this transition, an evolutionary change for which the function is not clear.
The likely answer is found in Longo’s research—a tantalizing morsel indeed. According to him, the nail-bed sensitivity may have allowed our forebears a richer sensual perception of their world, allowing them an enhanced ability to manipulate and engage with it.
If this sensorimotor function were truly in humans, it would have conferred a major benefit, enabling early humans to more accurately detect and respond to the textures, shapes and vibrations of the objects they encountered. Our dexterous hands and the ability to create a wide range of tools have long separated us from the rest of the primates, and reseachers at Stanford University think it may have been our uniquely protective-yet-vulnerable fingernails that helped drive this innovation.
While the specific evolutionary pathway is still open to debate, this discovery about the nail’s lost sensory capacity provides new clues about the extraordinary adaptations that have sculpted the human hand over a great deal of time stage.
Conclusion
Only the new phenomenon of a direct tactile localization underneath the fingernails! Not only does this new information paint a picture of the evolutionary function of such a characteristic but it shows how insanely intricate our body is at adapting to being able to feel through nails. As we attempt to uncover the secrets of our own biology, these studies remind us that there is still so much wonder left unturned and that a source of inspiration for further examination in nature lies just at our feet.
