Can Two People have Identical Fingerprints?

By Ritu Asthana; Illustration by Anup Singh

 

I was once watching a detective serial on T.V. where the fingerprints of the suspect are required. The hero invites the villain to his home and offers him a glass of water. The bad guy takes the glass and drinks the water from it. After he leaves the hero dramatically whips out a handkerchief and picks up the glass. His expressions showed that satisfaction at a job well done.

At that time, I found it amazing - how can smudges on a glass identify people? How can my hand be different from yours - apart from the size that is? It was only after my dad explained me the reason that the mystery behind that highly dramatic scene became clear.

My dad explained that if you were to press your thumb on an inkpad and then on a sheet of white paper you will leave a smudge or print, which no one else in the world can make. The same would be true for each of your fingers. The Chinese were the first to use fingerprints to affix their signature on important documents though they had no way of identifying or matching it with the owner.

If you look closely at the inside of your palm you can see tiny lines all over. These are absolutely unique and they remain practically unchanged from birth to death.

Each print is one-of-a-kind and no two people have the same characteristic. Scientists and criminologists (those who study criminal characteristics) determine the individuality of a fingerprint by a careful study of its ridge characteristics (minutiae) and not by its general shape or pattern.

The surface of the skin has been designed to provide our bodies with a firm grasp and to prevent objects grasped from slipping. Skin is composed of layers of cells. The outer portion of skin is called the epidermis while the inner skin is the dermis. Separating the two layers is a boundary of cells called the papillae.

Each skin ridge has a single row of pores that open out for the sweat glands. Once the finger touches a surface, sweat from these pores, along with other body oils layer the ridge of the skin and are thus transferred to that surface. The result is an impression of the finger's ridge pattern. Such prints are referred to as hidden fingerprints because they are invisible to the naked eye.

How this fact was discovered and now used by the police force worldwide is very interesting to trace. In 1823, John Evangelist Purkinji, a professor of anatomy at the University of Breslau in Czechoslovakia, published the first document on the nature of fingerprints.

In 1856, Sir William Herschel, who was then working for the Indian Civil Service in West Bengal, used thumbprints on documents as a substitute for signatures. In 1880, a British physician Henry Faulds, who was then working in Tokyo, published a paper suggesting that fingerprints left at the scene of a crime could identify the offender. However, Faulds never got the credit he deserved!

In 1892, an English scientist, Sir Francis Galton, published a comprehensive book on using fingerprints to solve crimes. At the same time in Argentina, a police researcher Juan Vucetich was also working towards a fingerprint classification system.