fingerprint patterns

Vintage illustration of Fingerprint Patterns.

Fingerprints have been collected, observed and tested as a means of unique identification of people for more than 100 years. 

The two basic ideas scientists believe about fingerprints are:
1. Fingerprints never change. Small ridges form on a person’s hands and feet before they are born and do not change for as long as the person lives.
2. No two fingerprints are alike. The ridges on the hands and feet of all people have three characteristics (ridge endings, birfurcations and dots) which appear in combinations that are never repeated on the hands or feet of any two people. 

In the over 140 years that fingerprints have been routinely compared world wide, no two areas of friction skin on any two people (including identical twins) have been found to contain the same individual characteristics in the same unit relationship. This means that in general, any area of friction skin that you can cover with a dime (and often with just a pencil eraser) on your fingers, palms, or soles of your feet will contain sufficient individual characteristics in a unique unit relationship to enable positive identification to the absolute exclusion of any other person on earth.

A person’s iris is as unique as a fingerprint. The galaxy-like patterns and the star-like specks make it look like a little universe. We all know the phrase “the eyes are the window to the soul” but have you ever studied someone’s iris and felt that their soul was really just a snapshot of the cosmos?

You will soon realize that this particular stranger is not a universe. They are the universe. The same one as you. In yet another disguise.

Your fingerprints might not be all that unique – and even if they were, there are a large number of variables that can make technically different prints seem very similar. See, getting the perfect fingerprint from a crime scene is something of a white whale. As often as not, investigators are lifting partial prints, which is how things can go haywire. Maybe fingerprints of you and Strong Dong Johnson, the Philadelphia Penis Strangler, share a bit of a coincidental similarity. A spot of bad luck later, and you’re on trial for crimes of the dick. Or what if your family member commits a crime? Yes,families share certain elements of their fingerprint patterns. Your brother’s the peeping tom, but you’re the one getting hurled in the back of a police cruiser. 

Although there are standards for determining fingerprint patterns, the actual matching of them is entirely on the shoulders of the expert handling the case. As such, fingerprint identification is an extremely delicate art. And by “delicate,” we mean “wildly subjective.” Experiments have found that even highly respected experts can be biased, to the point where they can change their minds about the same exact set of fingerprints based on what they know about a case.

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Wrinkle predictions: New mathematical theory may explain patterns in fingerprints, raisins, and microlenses

As a grape slowly dries and shrivels, its surface creases, ultimately taking on the wrinkled form of a raisin. Similar patterns can be found on the surfaces of other dried materials, as well as in human fingerprints. While these patterns have long been observed in nature, and more recently in experiments, scientists have not been able to come up with a way to predict how such patterns arise in curved systems, such as microlenses.

Pictured is a sphere with a combination of hexagons and labyrinthine patterns, and a more complex, torus-shaped object with hexagonal dimples.

Source: Massachusetts Institute of Technology
Picture credit: Norbert Stoop