Navigation Links
Urban myth disproved: Fingerprints do not improve grip friction

Fingerprints mark us out as individuals and leave telltale signs of our presence on every object that we touch, but what are fingerprints really for? According to Roland Ennos, from the University of Manchester, other primates and tree-climbing koalas have fingerprints and some South American monkeys have ridged pads on their tree-gripping tails, so everyone presumed that fingerprints are there to help us hang onto objects that we grasp. This theory that fingerprints increase friction between the skin and whatever we grab onto has been around for over 100 years, but no one had directly tested the idea. Having already figured out why we have fingernails, Ennos was keen to find out whether fingerprints improve our grip, so he recruited Manchester undergraduate Peter Warman to test out fingerprint friction and publishes his results on June 12 2009 in the Journal of Experimental Biology at

Because the friction between two solid materials is usually related to the force of one of the materials pressing against the other, Ennos and Warman had to find a way of pushing a piece of acrylic glass (Perspex) against Warman's finger before pulling the Perspex along the student's finger to measure the amount of friction between the two. Ennos designed a system that could produce forces ranging from a gentle touch to a tight grip, and then Warman strapped his index finger into the machine to begin measuring his fingerprint's friction.

But after days of dragging the Perspex along Warman's fingers and thumbs, it was clear that something wasn't quite right. Instead of the friction between each finger and the Perspex increasing in proportion to the amount that the Perspex pushed against Warman's fingers, it increased by a smaller fraction than Ennos had expected. Ennos realised that instead of behaving like a normal solid, the skin was behaving like rubber, where the friction is proportional to the contact area between the two surfaces.

To check that skin behaves more like rubber than a normal solid, the duo varied the area of each fingerpad that came into contact with the surface by dragging narrow and wide strips of Perspex along Warman's fingerpads. They found that the friction did increase as more of the fingerprint came in contact with the surface, so the skin was behaving just like rubber.

Finally, the friction issue was clinched when Warman measured his fingerprints' surface area. The area of skin in contact with the Perspex was always 33% less than if the fingerpads were smooth resulting in the maximum contact area. Fingerprints definitely don't improve a grip's friction because they reduce our skin's contact with objects that we hold, and even seem to loosen our grip in some circumstances.

So if fingerprints don't tighten our grasp on smooth surfaces, what are they for? Ennos explains that our fingerprints may function in other ways. They might have evolved to grip onto rough surfaces, like tree bark; the ridges may allow our skin to stretch and deform more easily, protecting it from damage; or they may allow water trapped between our finger pads and the surface to drain away and improve surface contact in wet conditions. Other researchers have suggested that the ridges could increase our fingerpads' touch sensitivity. Whatever our fingerprints are for, it seems that the idea that they provide friction for grip is just another urban myth.


Contact: Kathryn Knight
The Company of Biologists

Related biology news :

1. New pollution radar developed to provide unprecedented picture of urban smog
2. A win-win: U-pick pumpkin farms recycle urban leaves
3. The physics of star-forming clouds and the urban environment
4. Urban trees enhance water infiltration
5. Networks of small habitat patches can preserve urban biodiversity
6. UC Riverside scientist to explore how vegetation affects urban heat islands
7. Study: urban black bears live fast, die young
8. UMCES-led research team quantifies nutrient pollution reductions from urban stream restoration
9. Some migratory birds cant find success in urban areas, study finds
10. Influenza vaccine causes weaker immune response for children of rural Gabon than in semi-urban areas
11. Molecular fingerprints point the way to earlier cancer diagnosis and more targeted treatment
Post Your Comments:
(Date:11/12/2015)... 2015  Arxspan has entered into an agreement ... for use of its ArxLab cloud-based suite of ... partnership will support the institute,s efforts to electronically ... information internally and with external collaborators. The ArxLab ... the Institute,s electronic laboratory notebook, compound and assay ...
(Date:11/11/2015)... , Nov. 11, 2015   MedNet Solutions , an ... of clinical research, is pleased to announce that it will ... Trials (PCT) event, to be held November 17-19 in ... to view live demonstrations of iMedNet , ... how iMedNet has been able to deliver time ...
(Date:11/10/2015)... , Nov. 10, 2015 ... behavioral biometrics that helps to identify and verify ... Signature is considered as the secure and accurate ... identification of a particular individual because each individual,s ... accurate results especially when dynamic signature of an ...
Breaking Biology News(10 mins):
(Date:11/25/2015)... 26, 2015 --> ... 2016 - 2020 report analyzes that automating biobanking ... quality in long-term samples, minimizing manual errors, improving ... minimizes manual errors such as mislabeling or inaccurate ... it plays a vital role in blood fractionation, ...
(Date:11/25/2015)... 2 nouvelles études permettent d , ... les souches bactériennes retrouvées dans la plaque dentaire ... . Ces recherches  ouvrent une nouvelle voie ... de l,un des problèmes de santé les plus ... --> 2 nouvelles études permettent d , ...
(Date:11/25/2015)... HOLLISTON, Mass. , Nov. 25, 2015 ... HART ), a biotechnology company developing bioengineered organ implants ... McGorry will present at the LD Micro "Main ... 2:30 p.m. PT. The presentation will be webcast live ... Management will also be available at the conference for ...
(Date:11/25/2015)... 2015 /PRNewswire/ - Aeterna Zentaris Inc. (NASDAQ:  AEZS; TSX: ... prospects remain fundamentally strong and highlights the following ... received DSMB recommendation to continue the ZoptEC Phase ... the final interim efficacy and safety data ... men with heavily pretreated castration- and Taxane-resistant prostate ...
Breaking Biology Technology: