Fingerprinting is perhaps the oldest and most widely used method for individual identification. Due to their uniqueness and durability, fingerprints are used by law enforcement agencies, hospitals, and other organizations to identify individuals.
A fingerprint, in simple terms, is an impression made on different surfaces by ridges or lines on a human finger. These ridges are created by protrusions on the epidermis, the outermost layer of the skin also called epidermal ridges. Fingerprints help in gripping items with rough surfaces, and they also play an important role in the perception of fine textures.
Today, we will explore fingerprints in depth, including their history and importance, all while focusing on different types of fingerprint patterns.
Table of Contents
History of Fingerprint
Fingerprints have been known to humans for a long time. The earliest recorded use of fingerprints, or hand impressions, can be traced back to ancient Babylonia during the regime of King Hammurabi (1792–1750 BC) when officials used those imprints to validate written contracts.
Similar practices had been in place during the Qin Dynasty (221-206 BC) and Tang Dynasty (618–907 CE) China, where trade parties often took finger or palm impressions as a signature on trade contracts. The details of such practices were mentioned by Sir William James Herschel, a British Imperial officer who played a critical role in the development of fingerprints as a tool for individual identification.
Using the open-source 3D data visualization and display application GigaMesh Software Framework, archeologists have successfully extracted fingerprint impressions on ancient cuneiform tablets, pottery, and tombs.
Modern Fingerprint Analysis
While humans have been aware of fingerprints and their possible uses since at least 2000 years ago, the scientific studies on fingerprints only started in 18th century Europe.
The first significant breakthrough came in 1788, when Johann Christophe, a German anatomist, concluded that each individual has a unique fingerprint. Then in 1823, a Czech physiologist, Jan Evangelista, published a thesis that identified nine different fingerprint configurations, including the whorl and tented arch.
First fingerprints taken by William James Herschel in 1859
Fingerprinting, as we know it today, is largely about analyzing and comparing patterns for individual identification. Surprisingly, this practice was first implemented in India in the 19th century. In 1858, Sir William James Herschel (not to be confused with the astronomer William Herschel) initiated fingerprint collection in Kolkata, India. He would later endorse the use of fingerprints on deeds to prevent government pension frauds.
Henry Faulds, a Scottish surgeon, is one of the pioneers of fingerprinting analysis. In 1880, Faulds published a paper in which he suggested that each individual has unique fingerprints. He also analyzed the effectiveness of fingerprints as a method of individual identification.
Faulds’s ideas were later pursued by his relative Francis Galton, a British polymath and anthropologist. In his book published in 1892, ‘Finger Prints,’ Francis Galton analyzed the probability of two individuals having the same fingerprints. The likelihood of such occurrence was 1 in 64 billion.
The 1890s was an important decade for forensic science and the criminal justice system. Until the 1880s, law enforcement agencies depended on the physical measurements of body parts to identify criminals and convicts, which was not often a reliable method. It all changed in 1892 when Juan Vucetich, an Argentine chief police officer, created the first-ever fingerprint analysis method based on the works of Francis Galton.
Then in 1897, the first-ever fingerprint bureau was established in Kolkata, India, under the supervision of Sir Edward Richard Henry. The bureau was tasked with collecting and classifying fingerprints to identify criminals. It was during this time that Henry, along with two Bengali police officers Hem Chandra Bose and Azizul Haque, developed what later became known as the Henry Classification System of fingerprints.
Types of Fingerprint Patterns and Analysis
Today, various organizations, including hospitals, law enforcement agencies, banks, and even schools, use a fingerprint classification system to identify and categorize fingerprints based on their unique characteristics. It allows the matching of fingerprint samples against an extensive database.
Over the last two centuries, several such classification systems have been developed. The initial systems categorized fingerprints based only on general ridge features or formations, such as the presence or absence of a certain pattern on more than one finger. The most popular and widely used fingerprint classification systems are – the Henry Classification system and the Juan Vucetich system.
The Henry Classification system was developed in the late 1890s by Sir Edward Richard Henry, who was a high-ranking police official in British India. It was used by most English-speaking countries for over a century. The second classification system – the Juan Vucetich system, was developed around the same time in Argentina by a local Police officer and anthropologist, Juan Vucetich. The system is still in use in many South American nations.
Although a few other noteworthy classification methods are in use, such as the Rocher system, they’re largely based on either of the two systems mentioned above. The modern fingerprint classification system in most countries is built around the Henry Classification System.
In his classification system, Edward Henry identified three principle fingerprint patterns, namely Arch, the Loop, and Whorl. Over the years, researchers have been able to expand the system to include different subtypes or patterns. Thus, making it more complex.
Before we discuss different types of fingerprints, there are several basic patterns that one must know to fully grasp how fingerprints are interpreted and differentiated. These patterns are called Minutiae features.
Minutiae features | Image Courtesy: Inaki Rom/Wikimedia Commons
- Core: Located at the top of the innermost recurve
- Delta: Y-shaped location where two ridges converge
- Bridge/Crossover: A short line that connects two parallel ridges
- Bifurcation: Division of a ridge into two
- Trifurcation: Division of a ridge into three branches
- Ridge ending: The end of a ridge
Types of Fingerprints
In a general sense, a loop cannot be created without a recurve or a bend. This is also the case with fingerprints. Although there are other prerequisites for a pattern to be considered a loop, the most basic characteristic of a loop fingerprint pattern is an adequate recurve. Loops are the most abundant of all pattern types; 60-65 percent of all fingerprints are loops.
A loop must have an adequate recurve without any prominent appendages or projections that may change its shape. Loops must also feature a delta.
Examples of loop pattern
Loops can be further sub-divided into ulnar loops and radial loops.
Ulnar loop – Ulnar loop derives its name from a long forearm bone – ulna – that extends from the elbow to the little finger. Loops that are directed towards the ulnar bone, or the little finger, are called ulnar loops. In other words, ulnar loops are loops that open towards the little finger.
Radial loop – Instead of the little finger, if a loop opening is directed towards the thumb, it is identified as a radial loop.
Arches are the rarest type of fingerprint pattern found in only about 5 percent of all fingerprints. It is unique from the other two fingerprint types as it lacks cores and deltas. The ridges in the arch pattern run from one side of the finger to the other continuously without any recurve or bend.
An example of a plain arch
There are two types of arches –
Plain Arch – In a plain arch, ridges flow from one side of the finger to another side continuously with a gentle rise and a drop at the center. A plain arch is perhaps the simplest fingerprint pattern and can be easily recognized. It should be noted that plain arches may feature minutiae elements such as bifurcations, islands, and dots, but there is a consistency in their ridge pattern. The pattern closely resembles an ocean wave starting from one side of the finger to the other.
Tented Arch – The tented arch pattern is similar to a plain arch in which the ridges start from one end of the finger and flow towards the other end. The only notable difference between the two is the shape of the ridges at the center. The tented arch has steeper ridges, between 45° to 90° angles, at the center. Compared to a plain arch, a tented arch has a ‘tent-like’ shape.
Examples of tented arches
Some tented arch patterns can be easily confused with loops due to their identical appearance. They often feature loop-like converging ridges, which are initially misidentified as recurves. On the flip side, many fingerprint patterns that appear as tented arches are found to be loop patterns upon close examination.
The third main fingerprint type – the whorls are found in about 30-35 percent of all population. Whorls are generally characterized by the presence of a core and at least two deltas. Although this characterization of whorls is mostly the case, the pattern is often found in different variations. To better analyze the whorls, it is divided into four sub-types namely — the Plain Whorl, the Central Pocket Loop, the Double Loop, and the Accidental Whorl.
Plain whorl – As the name suggests, the plain whorl is the simplest and most common form of the whorl pattern. The plain whorl feature at least two deltas with several ridges forming a circular shape. At least one of those circular ridges makes a complete circuit, while others are impaired with a connected appendage that cannot form a circuit.
Central pocket loop whorl – The central pocket loop whorl is more like an advanced form of the plain whorl in which the initial circular ridge with a complete circuit makes a second recurve to create a pocket within the central loop. A straight or curved obstruction at the right angles to the inner side can replace the second recurve.
Double-loop – The double loop fingerprint pattern feature two distinct but connected loop formations. It features two different sets of loop shoulders and two deltas. The loops in the double loop pattern are not required to be of the same length and size.
An example of a double loop
Under Henry’s classification, the double loops were classified as ‘lateral pocket loops’ and ‘twinned loops.’ However, the two types were later merged into ‘double loop’ for the sake of simplicity.
Accidental whorl – The accidental whorl sub-category was basically created to identify and group fingerprint patterns that do not fall into any other aforementioned categories. Accidental whorls also include a combination of two different fingerprint patterns, excluding the plain arch (due to lack of any specific feature). It can be a combination of central pocket loop and double loop, tented arch and loop, or whorl and loop.
Henry Fingerprint Classification System | In-depth
The Henry Fingerprint Classification system has a total of nine divisions; six main and three extensions. The main divisions include – Primary, major, secondary, sub secondary, final, and key. The three extensions are the second-sub secondary, WCDX, and special loop extension.
These extensions were created and added by the Federal Investigation Bureau to better analyze more complex whorls and loop fingerprint patterns.
But before we dive deep into these divisions, you should know that under the Henry Classification system, each finger is assigned an appropriate letter – ‘i’ for the index finger, ‘m’ for the middle finger, ‘r’ for the ring finger, ‘p’ for the (pinky) little finger and ‘t’ for the thumb. The left and right hands are identified by the capital letters’ L’ and ‘R,’ respectively.
Moreover, Henry’s Classification is also called the ‘Ten-digit Classification system’ since it requires fingerprints from all ten fingers.
- Manual fingerprint analysis begins with primary classification.
- It analyzes whorl patterns on all ten fingerprints.
- Secondary classification focuses on index fingers and considers all fingerprint patterns.
- Sub-secondary classification focuses on the ring, middle, and index fingers for loops and whorls.
- The major division analyzes whorls and loops on both thumbs.
- The final classification focuses on little (pinky) fingers for Loops and sometimes whorls.
- Key classification analyzes loops on all but the little finger.
The primary classification is used exclusively to analyze or study the whorl patterns (including sub-types) in fingerprints. For primary classification, all the ten fingers are first grouped into five pairs (five pairs of two), then each pair is assigned a specific numerical value. If a whorl pattern appears on a finger, it assumes its set value. Else, it is given the value of zero.
|Finger Groups||Assigned Values (For Primary Classification)|
|(1) Right index + (2) Right thumb||16|
|(3) Right ring + (4) Right middle||8|
|(5) Right thumb + (6) Left little||4|
|(7) Left middle + (8) Left index||2|
|(9) Left little + (10) Left ring||1|
The values of odd-numbered fingers are added and placed in the denominator, while the sum of even-numbered fingers is placed in the numerator. Both the values are then added by 1. On either side, the maximum obtainable value is 32 (or 32/32), while the lowest is 1 (1/1). The highest value would indicate that the fingerprint has whorl patterns. On the other hand, the lowest value would mean no whorl pattern.
After the primary classification, fingerprints are further analyzed by secondary, sub secondary, major, final, and key classifications.
Why Fingerprinting has Became Necessary In Criminal Justice System?
Until the 1880s, police and other law enforcement agencies around the world identified criminals largely based on anthropometric measurements, also known as the Bertillon system. In this system, police officials recorded body measurements and features of the convicts including, length and breadth of head, length of foot and fingers, and eye color.
However, by the 1910s, it became quite evident that anthropometry was not as effective as fingerprinting as a method for personal identification. The importance of fingerprinting became evident in the criminal justice system after a few landmark cases that occurred between the 1890s and early 1910s.
The case of Francisca Rojas in 1892
The first homicide case on record to be solved with the help of fingerprint analysis took place in 1892 in Buenos Aires, Argentina. After a positive fingerprint match from the crime scene, the convict, Francisca Rojas, was arrested. Coincidentally, the case occurred only a few months after Juan Vucetich came up with his method of fingerprint analysis.
After this case, Argentina became the first nation to replace anthropometry with fingerprint classification (based on Vucetich’s system) to record the identification of criminal suspects and convicts.
The doppelgänger case of William West in 1903
Mugshots and fingerprints from William West case in 1903
In May 1903, a man named William West was sentenced to jail in Leavenworth Penitentiary, Kansas. Upon his arrival, West went through necessary anthropometric measurements, which eventually ended with a match of a previously convicted homicide offender. The name and the Bertillon measurements of William West were almost identical to the ones they had in their official records.
However, it was later found out that the real owner of that record was a different individual already serving a sentence in another jail. Both William Wests had identical faces and almost the same anthropometric measurements, but their fingerprints were completely different.
The case of Thomas Jennings in 1910
On September 19, 1910, Thomas Jennings was arrested in a Chicago neighborhood carrying a revolver about half a mile away from burglary and homicide that had just taken place. Upon investigation of the crime scene, the police found a fingerprint from a newly-painted railing. The investigators took photographs and samples of the fingerprints as they believed it would be defining evidence in the prosecution of this case.
Indeed, Jennings was convicted in court, and it thus became the first criminal case to be solved using fingerprints as evidence in the United States. The case proved to be the beginning of the shift towards using fingerprints in criminal cases in the country.
A Few Interesting Facts About Fingerprints
1. The Integrated Automated Fingerprint Identification System, or IAFIS, contains more than 51 million criminal fingerprint records and 1.5 million civilian records. It has been managed by the Federal Bureau Of Investigation (FBI) since 1999.
2. The Office of Biometric Identity Management (OBIM) under U.S Customs and Border Protection manages the country’s largest biometric repository called the Automated Biometric Identification System or IDENT. It contains the unique identities of more than 260 million individuals. IDENT is interoperable with the FBI’s IAFIS system, as well as, the Department of Justice and Department Of Defense.
3. The study of fingerprints is called Dermatoglyphics
The scientific study of fingerprints, including lines and ridges, is called dermatoglyphics. It is different from the pseudoscience of palmistry or palm reading. Dermatoglyphics also study naturally occurring ridges on other body parts such as palms, toes, and soles.
The term ‘dermatoglyphics’ was coined by American anatomist Harold Cummins in the 1920s. He is widely considered the father of dermatoglyphics. In 1929, Cummins along with other researchers, published the highly influential book Fingerprints, Palms and Soles; an Introduction to Dermatoglyphics.
4. Twins have different fingerprints
Contrary to popular belief, twins do not share similar fingerprints. There are two types of twins: identical and fraternal. While identical twins, born from the same egg, share similar physical characteristics and have the exact same DNA, the fraternal twins, born from two different sets of eggs and sperm, share only 50 percent of the DNA.
However, in neither case, can the twins have identical fingerprints since the formation of fingerprints is determined by both genetic and environmental factors inside the womb.
According to the Washington State Twin Registry, even though identical twins can have very similar fingerprints with a high correlation of whorls and loops, the details such as ridge patterns are always different.
In a 2012 study, a group of Chinese researchers, who analyzed large sets of fingerprints from identical twins, reached the conclusion that these fingerprints, although identical, can be distinguished by advanced fingerprinting methods.
5. There are certain genetic disorders that can prevent fingerprints from forming
Surgically removed fingerprints of criminal Alvin Karpis in 1933
There are a few rare genetic disorders that can cause individuals to have no fingerprints at all. Individuals who suffer from these conditions have abnormal ectodermal structures, including hair, nails, and sweat glands. These conditions are usually recognized as different forms of Ectodermal dysplasia.
- Naegeli syndrome, or Naegeli-Franceschetti-Jadassohn syndrome – This syndrome is characterized by skin pigmentation, disfunction of sweat glands, dental deformities, and lack of fingerprint lines. It is caused by a mutation in KRT14 gene.
- Dermatopathia pigmentosa reticularis (DPR) – This condition is similar to the Naegeli syndrome in which individuals suffer from brittle nails, hyperpigmentation, absence of sweat glands, and lack of fingerprints. The only difference between the two conditions is that individuals who are affected by DPR do not suffer from dental abnormalities. Due to this relatively minimal difference, Naegeli syndrome and DPR are usually considered a single disorder.
- Adermatoglyphia – Unlike the other two genetic disorders, adermatoglyphia doesn’t have any known symptoms other than a lack of fingerprint ridges. This condition is also known as “immigration delay disease”, due to the issues caused by no fingerprints at immigration and border control.
Apart from these genetic diseases, an anti-cancer medicine called capecitabine is known to cause fingerprint losses as a side effect among its recipients.
6. Fingerprint analysis can reveal recent drug usage
In 2020, Melanie Bailey, a professor, at the University of Surrey in the U.K, along with her fellow researchers, developed a test that can detect trace amounts of cocaine usage through fingerprints within minutes.
After ingesting cocaine, the human body excretes a toxic molecule called benzoylecgonine through sweat. Since the suspected cocaine user is constantly excreting the molecule through sweat, it is detectable through fingerprint analysis even after washing hands.
This method developed by Dr. Bailey and her team uses a specialized paper to collect fingerprints, which were then analyzed through the mass spectrometry technique to detect benzoylecgonine molecules. According to the team, it can detect trace amounts of the drug up to 48 hours of its consumption or use.
7. Some animals have fingerprints as well
Fingerprint-like ridges are also found on some animals, including chimpanzees, gorillas, and koalas. Scientists believe these animals have developed such characteristics due to their arboreal lifestyles: grabbing and climbing on objects and living on trees.
What’s more surprising is that fingerprints on koalas are almost identical to that of humans. The fingerprints of koalas are so similar to ours that they could easily be misidentified or mixed up.