Money Well Spent

Latent fingerprints. Latent means they're hidden, not yet revealed. The dermal ridges of the finger and palm (and the foot, for that matter) are an evolutionary remnant, an aid for gripping left over from the days when humans were just clever little mammals with a knack for climbing. Now these friction ridges are mostly useful for putting people in prison.

Fingerprints have been used for identification for over a century now, and in all that time no two prints have been found to have the same characteristics. Even identical twins have unique fingerprints. Tens of millions of dollars each year are spent on collecting, storing, and comparing fingerprints.

A roll of paper towels for wiping away fingerprints costs maybe a buck.