For a long time, scientists believed that the patterns on our fingertips were designed to grip objects more tightly. But in reality, they do not improve the "grip" in any way, but rather reduce the friction between the skin and the object, especially if it is smooth.
Researchers studied the friction hypothesis and found that leather behaved like rubber in this case. In fact, the skin patterns on our fingers reduce our ability to grip objects because they reduce our contact area with the thing we are holding. Therefore, the question remains open, why do we have fingerprints? The theories are: better "grip" of rough or damp surfaces, protection of fingers from injury, and increased sensitivity.
How do finger patterns appear?
So, fingerprints are patterns on their tips. They appear when we are in the womb and they are fully formed by the seventh month. We all have unique personalized fingerprints for life. Even twins with identical DNA have fingerprints.
The prints are made up of patterns in the form of arcs, loops and curls that form in the innermost layer of the epidermis: the basal cell layer. Basal cells are constantly dividing and new cells are being promoted into the layers above. The number of basal cells in the fetus grows faster than in the outer layers of the epidermis and dermis. This vigorous growth causes the basal cell layer to form many patterns, and damage to the surface layer will not change fingerprints.
Why do some people have no fingerprints?
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Dermatoglyphia is our custom design on fingers, palms, feet and toes. The absence of these patterns is due to a rare genetic condition called adermatoglyphia. Scientists have discovered a mutation in the SMARCAD1 gene, which is the reason for the development of this condition.
Fingerprints are fully formed at 24 weeks gestation and do not undergo any changes throughout life, however, the factors underlying the formation and structure of fingerprints during embryonic development are not well understood. Although there is still a certain gene that is involved in the development of patterns on the fingers, as well as the development of sweat glands.
Finger patterns and bacteria
Researchers at the University of Colorado (Boulder) have demonstrated that bacteria found on the skin can be used as personal identifiers, since they are unique even among identical twins. And these bacteria remain on the objects that the person touches. By examining the DNA of bacteria found on the surface, we can compare it with the hands of the person who left these bacteria. In fact, this is an analogue of fingerprints, very unique and able to remain unchanged for several weeks. Bacterial analysis can be a useful tool in forensic identification when it is impossible to isolate human DNA or obtain clear fingerprints.
