Fingerprints are the imprint made by the tiny pattern of ridges on the tips of your fingers and thumbs. These are called “papillary” or “epidermal” ridges. Generally these ridges look like arches, whorls, or loops. Can you tell which kind of pattern you have?

Even though there are only a few types of patterns, no two people in the entire world have the exact same fingerprints. Fingerprints are actually more unique than DNA (genetic material that determines many of a person's characteristics). For instance, identical twins have the same DNA, but they still have different fingerprints!

This can happen because the formation of fingerprints is controlled by a developing baby’s environment in addition to their DNA. The pressure, density of amniotic fluid, and umbilical cord length in the womb all contribute to the pattern of a baby’s fingerprint. Because the pattern is formed beneath the outer surface of the skin, a person’s fingerprints do not change with age, growth, or minor injuries. In modern society, fingerprints have become a way to identify people for things like criminal investigations.

But why do humans have fingerprints in the first place? Fingerprints are only found in humans and our ancestors, chimpanzees, gorillas, and koalas. Scientists think fingerprints must serve a purpose for all of these animals, but haven’t fully determined what that purpose might be.

Some scientists have proposed that fingerprints could help improve grip. Grip is important for anything from holding objects to climbing. However, because of the physics of skin and the texture of the ridges, the idea that fingerprints help with grip isn’t widely supported. It is still possible that fingerprints improve our ability to grip objects when they’re wet or slippery, just like how the ridges in car tires help people drive when roads are wet.

More scientists support the idea that the ridges on our fingers could help improve our sense of touch. They think that the ridges may amplify vibrations when we touch something, which helps us sense more detail about it. Hands and touch have always been crucial for humans, our ancestors, and other animals. As just one example, touch and texture can help determine if food is good to eat or rotten. The other standing theory is that fingerprints may help reduce blisters. Scientists are still trying to put their finger on the reason fingerprints exist today!