Dactyloscopy - the science of identifying a person through fingerprints is now effectively used in various fields.
William Herschel served in the British administration in India at the end of the 19th century. He is surprised that the number of soldiers coming to get paid is increasing every year. He could not get to the bottom of this phenomenon. Because he could not distinguish Indians based on their appearance. Representatives of the local population skillfully used this - one day they received a salary, and the next day they sent a relative to receive the salary. Moreover, most of them were illiterate.
Hershel, impatient at the end, demanded that they leave their fingerprints on the bill and his last name on the list. Upon closer inspection, one person's fingerprint was not identical to another's. After that, flipping through anatomy textbooks, he based his discovery on papillary lines on the finger.