WEBVTT - Why Are Fingerprints (Almost) Unique?

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<v Speaker 1>Welcome to Brainstuff, a production of iHeartRadio, Hey brain Stuff,

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<v Speaker 1>Lauren Voge bomb here A. One of life's great marvels

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<v Speaker 1>is that, much like snowflakes, no two fingerprints are alike.

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<v Speaker 1>This even goes for identical twins who split from the

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<v Speaker 1>very same egg and sperm. Although it's not entirely impossible

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<v Speaker 1>for two fingerprints to match up, the odds are way

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<v Speaker 1>against it, as in like one in sixty four billion,

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<v Speaker 1>definitely not odds you want to take to Vegas. Fingerprints

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<v Speaker 1>have been studied for millennia, but the FBI today identifies

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<v Speaker 1>eight primary types of fingerprint patterns. These include four types

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<v Speaker 1>of loops, two types of arches, one type of whirl,

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<v Speaker 1>and a so called accidental type, which combines characteristics of

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<v Speaker 1>all three patterns. But even within those patterns, there's tremendous

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<v Speaker 1>potential for differences in spacing, depth, angles, m so on.

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<v Speaker 1>A prince pattern depends on a potent and unique combination

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<v Speaker 1>of genetics plus environment. During development. A human skin is

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<v Speaker 1>easily affected by its environment, and that's why people who

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<v Speaker 1>spend a lot of time in the sun or doing

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<v Speaker 1>manual labor tend to have freckled, sunburned, or tougher skin

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<v Speaker 1>than those who don't. This trait begins in the womb.

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<v Speaker 1>As a fetis grows, the epidermis and the dermis, that is,

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<v Speaker 1>the outside and inside layers of the skin, come together naturally,

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<v Speaker 1>which produces friction ridges. The ridges get their basic design

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<v Speaker 1>from the genes of the baby's parents, but fetal cells

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<v Speaker 1>work at their own individual pace, which causes the skin

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<v Speaker 1>to grow and stretch and move in different ways. A

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<v Speaker 1>fetus's budding fingerprints, which develop between thirteen and nineteen weeks

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<v Speaker 1>of gestation, can also be influenced by the nutrients it's getting,

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<v Speaker 1>how it's positioned in utero, or even if it rubs

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<v Speaker 1>against the wound more umbilical cord. Once a fingerprint is developed,

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<v Speaker 1>it remains static for the life of the person in question,

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<v Speaker 1>barring major damage from things like skin diseases, burns, or scarring.

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<v Speaker 1>Even the most identical of twins can experience individual genetic mutations,

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<v Speaker 1>making them ever so slightly different from one another. As

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<v Speaker 1>we develop, signaling pathways help our genes communicate to complete

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<v Speaker 1>their individual instructions. These are very sensitive to the womb's environment,

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<v Speaker 1>which is why identical twins aren't one hundred percent genetically alike,

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<v Speaker 1>as was previously thought. According to a study published in

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<v Speaker 1>the journal Cell in twenty twenty three, three different chains

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<v Speaker 1>of signaling in particular, appear to affect how the fingerprint develops.

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<v Speaker 1>Some pathways have been found to tamp down the growth

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<v Speaker 1>of ridges, whereas others encourage them to develop. A Meanwhile,

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<v Speaker 1>a third kind affect how big or small ridges or

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<v Speaker 1>whorls are, and also how they're spaced out. Since everyone's

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<v Speaker 1>pathways and signals are different, these effect how the fingerprints

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<v Speaker 1>turn out. In short, abzilion little factors come into play

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<v Speaker 1>when skin layers first form to create something that's truly

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<v Speaker 1>one of a kind. And in case you're curious, just

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<v Speaker 1>because non human animals might not have fingers per se,

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<v Speaker 1>that doesn't mean that they don't develop similarly unique traits.

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<v Speaker 1>For example, cats and dogs have unique noses. The pattern

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<v Speaker 1>of bumps on the nose of each dog and cat

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<v Speaker 1>is their own, and much like fingerprints on humans. Today's

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<v Speaker 1>episode is based on the article why even identical twins

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<v Speaker 1>have different fingerprints on HowStuffWorks dot com, written by Leo Hoyt.

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<v Speaker 1>A Brainstuff is production of iHeartRadio in partnership with HowStuffWorks.

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