Fingerprints Do Not Improve Grip

A study by biomechanicist (apparently, there's such a thing) Roland Ennos and Peter Warman of the University of Manchester, UK, has just blown away decades of conventional knowledge: fingerprints do not increase our grip - instead, it reduces it!

Rather than singe the prints off an unlucky student to compare hands with and without prints, Ennos rigged Warman's fingers to a special device that slides a weighted sheet of Perspex across a finger and measures the resulting frictional force.

Ennos and Warman determined that the amount of friction generated went up as more of the fingerprint was touching the sheet, but not by as much as expected. This indicated that the skin was behaving like rubber, where friction is proportional to the contact area between the two surfaces.

So, if not for increasing grip, then why do we have fingerprints? Scientists think that fingerprints may improve tactile sensitivity, help water wick off fingers, and reduce shear stress.

Link - via GeekPress


"... then why do we have fingerprints?"

Ultimately, the answer is, "Because it was God's will for mankind." He knew that it would be better for us to have them than not to have them. He knew about identification by fingerprint before He created the first man and woman.
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re: "This indicated that the skin was behaving like rubber"

And for our US friends read "eraser" in place of "rubber"
(Although the use of the word rubber does make the article more entertaining...)
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Incorrect. Fingerprints on smooth dry surfaces do not improve grip. Fingerprints on wet surfaces (I forget if it is smooth or not smooth) can improve grip. The people who tested this are still figuring it out but right now, it appears that fingerprints are helpful with grip when a surface is wet.
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I wonder if they tried wet fingers. I know my hands grip better when they are a bit clammy. If our ancestors evolved in warm, tropical places, they may have been more sweaty than us in our modern, temperature controlled habitat. Maybe the combination of fingerprints and sweat are what nature was going for.

I wonder how fingerprints perform on materials like wood or tree branches. I'm pretty sure our ancestors would not have encountered a material like a laboratory friction test plate in nature.
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Improving sensitivity is part of it. When I wore all my prints off my fingers were very sensitive, but only to static things - sliding smooth fingers across things doesn't give such a good idea of what the surface is as when you have prints.
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Not every trait has to be useful. It could simply be that the growth process that results in fingerprints (the shrinking skin layers of the fetus) is the simplest, most efficient growth process.

In other words, fingerprints could be a useless bi-product.
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I think this researchers conclusions are grossly incomplete. Yes there are some advantages to molecules (your skin and a piece of paper) being as close together as possible (Casimir effect)... but on heavier objects this effect would be negligible and I would suspect interlocking molecules (from fingerprints) would hold the advantage.

Also I must admit I may be too hungover to know what I'm talking about =c)
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Hold it. Our early ancestors lived in caves and threw sticks and stones. I don't see how fingerprints would make a difference in such an environment. Hence it has no evolutionary benefit, hence it has no specific purpose.
Am I dumb or are the scientists dumb?
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So they did a single experiment and drew all their conclusions from that? Bad science. In fact, I wouldn't even call it science; I've seen better high-school projects.
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Uh, fingerprints are biometrics provided by the aliens that planted us here - DUH. Why do you think they work so good to catalog criminals. Whenever one of us is abducted they just run us across the checkout scanner and *beep* humin # 299837746382.
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Fingerprints providing better grip has been speculative, but so are these findings. They are attempting to rule out a popular assumption with another assumption - and by a single test.

Pointless.
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Yes, bad science here.

I might suggest that smooth surfaces are very rare in the natural world, and that fingerprints do help us grip rough objects, made of wood or stone.

But perhaps this pointless controversy will allow the researchers to grip some more funding.
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Bad science indeed. Only checking against an extremely smooth surface? There are very few, flat, glassy smooth, and dry surfaces in nature. Do that same experiment with a natural stone, a tree branch, etc. and they will have drastically different results.

Since we did not evolve with Perspex, then it is doubtful that a surface like that has anything to do with fingerprints. I read another case (can't remember the researchers of course) and they found that slightly sweaty bare hands and feet produced a superior grip when climbing trees.

I love Neatorama, and know it is mostly about entertainment, but please don't act like the "real" media and report on any study that is published. The national news does this constantly. Anybody can set up a study to produce skewed results, that's why science relies on repetition of studies to compare results.
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Once upon a time, I was doing a little metalworking in my garage. I grabbed a hot piece of steel (sans gloves) and burned all of my fingerprints off most of my fingers. For about a week, I had an impossible time at my day job. Part of my job involved separating the yellow copies from the white copies on carbon-copy receipts.

I can assure you, fingerprints were indeed useful for that. I did the same tasks with and without fingerprints, and I noticed a difference.
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The characterization of skin as rubber is a good result. The interpretation that this means fingerprints do not increase grip is invalid.

Frictional behavior in rubber is known to be highly dependent on wetness and macroscopic roughness, especially in dynamic loading (sounds dirty). The study does not encompass any of these variables.
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