Evidence explains why we have fingerprints

Fingerprints do not hold the primates as they once thought, scientists have recently discovered. In fact, they reduce the friction needed to grasp smooth surfaces. Now Dr. Roland Ennos and the University of Manchester team are working hard to find out: why do we have fingerprints?

Dr. Ennos of the Department of Life Sciences, University of Manchester, said: ' I've been thinking about this problem for years and have studied it. I realized that the skin has the properties of rubber so the fingerprint lines actually reduce grip. '

'Our experiment - using a plastic cup to create a simple machine in the laboratory - proved that I was right.'

He added: 'Interestingly, not only fingerprints of primates, but koalas belonging to the marsupial group also have hand marks. Meanwhile the monkeys in South America have a pattern on their tail. '

'So what are those things for? The hypothesis that I think is appropriate is that these animals allow the skin to change, thereby avoiding blistering. That's why we get blisters on the software on the hands and feet, not in the folds, for example, the palms of the hands or feet ".

'We are now verifying this hypothesis with two other hypotheses that fingerprints increase grip for objects with grainy surfaces, and they increase skin sensitivity'.

With a simple machine - including 3 pieces of pecpech glass and the help of student Peter Warman, Dr. Ennos dismissed the long-standing view that fingerprints help primates understand. They tested Peter's ability to hold onto each finger and thumb at three different widths of pecpech glasses when the machine pulled down pecpech glass pieces with a weight placed in a plastic cup. They also tested the grip ability at three different angles by folding fingers and thumbs. This changing study condition allows them to separate the force from the contact surface and avoid the factors that fail the experiment.

The team published their results in the Journal of Experimental Biology in June 2009. They found that rubbing increased with area, which was in contrast to normal physical rules. The idea that rubbing does not change with surface area. This is due to the fact that the skin is rubbery and not a normal solid.

Fingerprint.(Photo: elasticmind)

The team also conducted a determination of the contact area by covering fingers and thumbs with ink, then fingerprinting with different pressures. This shows that fingerprints reduce contact area by 1/3 compared to smooth skin, thereby reducing rubbing.

The results show that the fingertip is more like rubber than the ordinary solid, its rubbing coefficients decrease for strong forces, and the coefficient of rubbing is higher when the finger is flattened. on larger slabs, so the contact area is also larger. The deformation pressure is also greater at higher pressures, indicating the presence of biofilm between the skin and the surface.

Fingerprint reduces contact area by 1/3 compared to smooth skin, but it reduces rubbing. This has caused doubts due to their support function. Dr. Ennos said: 'This experiment is very simple, the discovery should have been discovered 100 years ago, but scientists make assumptions and seem to have looked at complicated angles. than.'

'I tend to think differently, I am interested in the question of why and looking at things that affect people in their daily lives. Everyone thinks that science is about all that is impossible, but it is not so. Science helps us understand the world around us. '

He added: 'There are also some additional benefits in this work. For example, some people who suffer from nerve damage that inhibit sweating have smooth fingers that cannot be grasped. We can develop a device to treat this disease. '

He and his team will conduct experiments to see how fingerprints affect the grip on rough surfaces and on wet surfaces, so that observing whether its function is moving water to another place with the grooves in the hand or not. They will also test whether fingerprints help limit blistering, and if so, how.

References:
'Fingerprints are Unlikely to Increase the Friction of Primate Finger Pads,' Experimental Biology Magazine (June 2009)