how do fingertips work? What makes them so unique and why they generate on the fingers and not other parts of the body?


how do fingertips work? What makes them so unique and why they generate on the fingers and not other parts of the body?

In: Biology

Every part of your body is unique. Fingerprints are just exceptionally easy to tell apart and, more importantly, to *collect* since everything gets touched by fingers.

All of your body is unique. It’s possible to identify people just by the shape of their hand if you use spacers to hold the fingers in place. Same with retinas, face proportions etc.

Fingerprints just get more attention because they’re a small area and have been historically important for identifying people as we leave them everywhere. They are also easy for us to see. But there is nothing more unique about them then any other part of your body.

Technology wise there is a big move away from fingerprints as an identifying mark because people have dirty hands, and so the reader is less reliable without frequent cleaning. Your phone, CCTV surveillance, Facebook tagging your photos etc use facial recognition.

As others have said there’s other parts of your body that are unique so I’ll try to explain why they’re unique. Imagine you have a picture of a thumb print. On that picture you pick 100 points and measure the angle/direction of the print and its relative height. If you round to the nearest 10° and assign binary to peak or trough height, there would mean there’s a theoretical maximum number of possiblities of (2*18)^100 or 0.42*10^156 (42 followed be 154 zeros). Theres been an estimated 120 billion humans to ever live or 0.12*10^12. So there’s way way way more possible thumb prints than people to have ever existed. There are common patterns in prints that means the real number is much smaller but you start with so many possibilities that it doesn’t matter. You’re fingerprints are like QR codes, they all kinda look similar but it’s the little differences that make them so unique.

You do in fact have a “skin print” as well, that is also quite unique.

Take a very close look at a part of your body with minimal hair. You’ll see ridges and divots, pores, scars, lines. All identifying markers.

The reason we don’t use “skin prints” is twofold.

First, a “skin print” is not nearly so clear as a finger or hand print because it is obscured by hair. We don’t grow hair on our hands or fingers. We also have the added benefit of deep valleys and ridges on our hands and fingers. These are there to give us grip, and they leave a clear impression behind when we touch something.

The second reason is convenience. It is far simpler to use your fingerprints than any other part of you. We more often leave fingerprints behind than any other type of clear impression. It is easier to take fingerprints from people than it is to take skin or even toe impressions.

To answer your question about how fingerprints form:

In the womb, we are formed in a specific way. Your heart, for example, begins upside down and twists into place as it grows. Similarly, your skin grows in a very specific way to form the characteristic rings on your fingers. These rings are loosely aligned with innervation that responds to moisture. In the wet, your fingers wrinkle to increase grip. Your fingerprints are your “dry weather” grip.