The usual explanation for the presence of fingerprints, handprints, and footprints is to enhance friction and thus improve our ability to walk upright and to make and use tools.
However, recent evidence shows that these friction ridges (epidermal ridges) may also enhance our ability to sense fine textures on surfaces.
Researchers have found that artificial ridges similar to human epidermal ridges used with an artificial sensor were able to filter vibrations produced as the ridged surface brushes over a textured surface. This "filter" permits only vibrations around 250 Hz to reach the sensor--the same vibrational frequency detected by lamellar corpuscles (Pacini corpuscles) in the skin.
So the thinking is that skin ridges enhance the function of lamellar corpuscles and thus enhance our ability to sense fine textures.
Want to know more?
Fingerprints filter the vibrations fingers feel: ridges may help make touch sensation efficient
Science News February 28th, 2009; Vol.175 #5 (p. 10)
[Summary article discusses the implications of the recent research.]
The Role of Fingerprints in the Coding of Tactile Information Probed with a Biomimetic Sensor.
J. Scheibert, S. Leurent, A. Prevost and G. Debrégeas
Science, 29 January 2009. doi: 10.1126/science.1166467
[The original research report]