Fingerprints have long proven their usefulness in solving crimes, but researchers from Sweden have now also discovered that they are crucial to our sense of touch. The ridges on our fingertips appear to be very closely related to the sensory nerve cells with which we can perceive all kinds of stimuli.
Fingerprints are always unique, even in twins, the characteristic ridges on the fingertips form a different pattern. They are therefore very useful to identify people, for example to solve crimes. But until now, it was highly unclear why Mother Nature gave us those skin lines. Researchers at the University of Umeå in Sweden are now partially answering that question: they would play an important role in our sense of touch.
Activity of sensory nerve cells
The scientists came to that conclusion after an experiment in which they focused on sensory neurons, or sensory nerve cells. One hand contains tens of thousands of such nerve cells, which direct stimuli – such as heat, pressure and vibration – to our central nervous system, making us feel them effectively. Each of those neurons is connected to a tiny zone in the skin, which explains why we can feel things so well with our hands.
Until now, it was still unclear exactly how sensitive a single sensory neuron is. The Swedish researchers therefore analyzed the electrical activity of the sensory nerve cells in their fingertips in 12 people, while stimulating them by running over their skin paper with microscopic bulging dots.
This allowed them to visualize in detail where the stimuli were occurred on the fingertips. Those ‘sensitive hotspots’ turned out to be very small, with a width of about 0.4 millimeters, which is not coincidentally also the width of the ridges from which our fingerprints are made. The hotspots also followed the same patterns as the subjects’ fingerprints. For example, the study shows for the first time that the sensory nerve cells are linked to the ridges on our fingertips, which makes our sense of touch along these unique skin lines particularly fine-tuned. So we can certainly speak of a specific ‘fingertip feeling’.
Possible other features
The researchers do point out that our fingerprints may also have other functions. For example, it has long been thought that they might be useful in grabbing things, by improving our grip on things and helping to remove water from our hands.