Fingerprint ridges allow primates to regulate grip
| Autor: | Gun-Sik Park, Matlabjon Sattorov, Kihoon Eom, Jeongmin Jang, Dongpyo Hong, Kyunghoon Jung, Michael Adams, Sung Wan Kim, Min Geol Lee, Juhan Kim, Seontae Kim, In Keun Baek, Seonmyeong Kim, Seoung Mok Yum |
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| Rok vydání: | 2020 |
| Předmět: |
Adult
Male Primates Materials science Friction Capillary action Microfluidics Evaporation Fluid layer 02 engineering and technology Slip (materials science) Motor Activity Fingers Fingerprint Animals Humans 0501 psychology and cognitive sciences 050102 behavioral science & comparative psychology Dermatoglyphics Composite material Sweat Multidisciplinary Hand Strength integumentary system Moisture 05 social sciences Epidermal Ridge 021001 nanoscience & nanotechnology Biological Evolution Sweat Glands body regions Excess water Physical Sciences 0210 nano-technology Locomotion Tomography Optical Coherence |
| Zdroj: | Proc Natl Acad Sci U S A |
| ISSN: | 1091-6490 0027-8424 |
| Popis: | Fingerprints are unique to primates and koalas but what advantages do these features of our hands and feet provide us compared with the smooth pads of carnivorans, e.g., feline or ursine species? It has been argued that the epidermal ridges on finger pads decrease friction when in contact with smooth surfaces, promote interlocking with rough surfaces, channel excess water, prevent blistering, and enhance tactile sensitivity. Here, we found that they were at the origin of a moisture-regulating mechanism, which ensures an optimal hydration of the keratin layer of the skin for maximizing the friction and reducing the probability of catastrophic slip due to the hydrodynamic formation of a fluid layer. When in contact with impermeable surfaces, the occlusion of the sweat from the pores in the ridges promotes plasticization of the skin, dramatically increasing friction. Occlusion and external moisture could cause an excess of water that would defeat the natural hydration balance. However, we have demonstrated using femtosecond laser-based polarization-tunable terahertz wave spectroscopic imaging and infrared optical coherence tomography that the moisture regulation may be explained by a combination of a microfluidic capillary evaporation mechanism and a sweat pore blocking mechanism. This results in maintaining an optimal amount of moisture in the furrows that maximizes the friction irrespective of whether a finger pad is initially wet or dry. Thus, abundant low-flow sweat glands and epidermal furrows have provided primates with the evolutionary advantage in dry and wet conditions of manipulative and locomotive abilities not available to other animals. |
| Databáze: | OpenAIRE |
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