Why do we have fingerprints?

Fingerprints help us in gripping（抓住）and handling（触摸）objects in all kinds of conditions．They work in the same way asthe tires（轮胎）of a car．While smooth surfaces are fine for gripping in a dry environment，they are useless in a wet one．So we have developed a system of troughs（槽）and ridges（脊）to help lead the water away from the fingertips，leaving a dry surfacewhich allows a better grip．The unique（独特的）pattern is also useful for the policetoidentify（确认）people．