By Taylor Tibbs
Every single person on the planet has a unique set of fingerprints – even those of identical twins are different! With almost 8 billion people on earth, how in the world do we each have our very own fingerprints?
Our fingerprints are formed when we are a fetus. At 8 weeks old, we begin to sprout the tiny nubbins that will become fingers. While we are developing in utero (inside our mother’s uterus), our growing fingers come into contact with our surroundings. At this stage in our life, our most immediate surroundings are the amniotic sac, which is filled with fluid and surrounds the fetus within the uterus . Essentially our fetal selves are floating around inside a water balloon. And much like a balloon, the amniotic sac has a thin bendable membrane filled with pressurized fluid. As our fingers are subjected to pressure from the fluid around us and as we touch the wall of the amniotic sac, the soft developing skin of our fingertips bend and wrinkle, forming “friction ridges” or the swirls and lines of our fingerprints. Prints on the palm of the hand and the bottom of the feet are also formed this way. Since no two babies will move about in the amniotic sac the exact same way, not even identical twins have the same fingerprints!
Fingerprints come in three basic patterns or dermatoglyphs: loop, whorl, and arch. Loops are the most common and make up 60% of all fingerprints, while arches are the least common and make up 5% of all pattern types. Although fingerprints can be grouped into these basic patterns, the exact spacing between ridges remains unique. Even crazier, no one has the exact same fingerprint on more than one finger. You may have a whorl on your pinky and an arch on your thumb. Not only are our fingerprints unique, but each one of our individual finger’s fingerprints are unique!
To better view fingerprint patterns, fingertips are often dipped in ink and blotted onto paper. This is what happens when you are watching Law and Order and hear they “fingerprinted the perp.” Because everyone’s fingerprints are unique, it has become a powerful tool within the justice system for establishing whether a person was at the scene of a crime. The oil naturally produced by our skin can leave our fingerprints on a variety of surfaces, like tables, glasses, and doorknobs. Investigators can collect these fingerprints and then compare them to ink-blotted prints to identify if they are a match.
Not only are fingerprints unique, but they are also permanent. Even when fingerprints are damaged, the new skin grows back in the exact same pattern that was formed in the womb. Our fingerprints follow us from cradle to grave. Fascinatingly, it is possible to be born without fingerprints! Individuals with adermatoglyphia do not have fingerprints due to a genetic mutation. Genetics can influence the pattern of fingerprints, but it’s complicated. Scientists don’t yet understand all the genes that contribute to fingerprint development.
Even though science is playing catch-up on the inner workings of fingerprint formation, we do know a few key things: 1) fingerprints are unique to an individual regardless of genetic identity, and 2) fingerprints are permanently imprinted onto our skin while in the womb. Next time you are unlocking your smartphone with the touch of your finger, you might wonder, “what kind of fingerprints do I have?”
