How fingerprints are formed
The ridges on your fingers which create ‘fingerprints’ are formed in weeks 10 – 15 of the foetus’ time in the womb.
Before this period, foetuses have volar pads on their fingers. These are smooth pads caused by the development of blood vessels and connective tissue. During week 10 – 15, these pads are absorbed back into the hand, as the hand continues to grow. This is when the ridges begin to appear on the pads which will become your fingertips.
The timing of when these ridges appear affects which pattern your fingerprints will end up with. If the volar pads are still very prominent, you will gain a whorl pattern. A less exposed volar pad leads to a loop pattern, and a volar pad which has nearly been reabsorbed by the time it produces ridges will result in an arch pattern.
These patterns are influenced by your parental genes, so family members’ patterns are likely to be similar. The unique identifiers are formed by the unique effects of the surroundings, such as the foetus moving around inside the womb, the density of the amniotic fluid, and the pregnant person’s blood pressure.
The scientific name for fingerprints is ‘dermatoglyph’
… and the name for the study of fingerprints is Dermatoglyphics.
These words come from two Ancient Greek words.
- Dermato – from derma (skin)
- Glyph/Glyphics: from gluphikós (sculpted)
There are three different types of fingerprint patterns
These three types are the starting point for all fingerprint comparisons. Analysts then look at the print in further detail to spot the unique features.
- Loops. These can point either towards the thumb or the little finger, and are the most common fingerprint type at 60% occurrence.
- Whorls. These circular or spiral patterns come in several different forms, and make up about 35% of fingerprints.
- Arches. This rare type is wave-like in shape, and account for 5% of the population’s fingerprints.
Koalas have them too!
It may not surprise you to be told that chimpanzees have finger ridges like ours which produce fingerprints. They are, after all, our nearest relatives in the animal kingdom. However, there is a much more unexpected animal with fingerprints so close to ours that they could confuse a fingerprint scanner: the koala.
The koala is a marsupial, despite its commonly used nickname of ‘koala bear’. It is only found in Australia, and its last common ancestor with humans was 160 million years ago!
Exactly why it has developed fingerprints is a mystery. You can see an example of a koala fingerprint here.
Identical twins have different fingerprints
Identical (monozygotic – “from one egg”) twins are nature’s clones. Born from the same egg and sperm, they share 100% of their DNA. However, their fingerprints will always be unique.
As discussed in 1, this is because the exact design of your fingerprint is not determined by your genes, but is affected by the environment inside the womb.
A study has shown that although commercial fingerprint readers can distinguish between identical twins, it is with a slightly lower accuracy than other family members because of the much stronger genetic influence.
Some people are born without fingerprints
Three very rare genetic conditions can prevent fingerprints (and all other friction ridges on the hands and feet) from forming at all:
- Naegeli-Franceschetti-Jadassohn syndrome (NFJS). This is a genetic problem with a layer of the body, formed early in development. As well as the striking absence of fingerprints, suffers also have a decreased ability to sweat and a loss of teeth.
- Dermatopathia pigmentosa reticularis (DPR). This is very similar to the above condition, as both are caused by the same gene mutation. Both are dominant and so can be passed down to children if only one parent has the condition. The main difference between this and NFJS is that DPR doesn’t lead to problems with the teeth.
- Adermatoglyphia. Unlike the previous two, this mutation has no other known side effects apart from the lack of skin ridges. In 2009, researchers nicknamed this the “immigration delay disease”, for the problems that a lack of fingerprints causes with biometric border control.
British police once ordered an entire town to submit their fingerprints
In 1948, police ordered a mass fingerprinting of all men over 16 in the Lancashire town of Blackburn to try and catch the person who had killed a child.
The perpetrator had left his fingerprints on a glass bottle (alongside several other pieces of evidence such as a boot-print) but they didn’t match anything the Blackburn police had on record. In an unprecedented move, the police not only sent those fingerprints to every police force in the UK, but ordered the collection of fingerprints from every man over 16 in Blackburn.
He was identified as the 46,253th set of prints collected, and he was hanged.
The police promised to destroy their collected fingerprints, and these days it is very unlikely that the British police could ever compel the public to share their identifying information like this.
Ancient fingerprints have been preserved for thousands of years
If ancient people happened to leave their fingerprints on the right kind of surface, we can still see them today.
- 1000 BC – an Ancient Egyptian coffin craftsman left his fingerprint on an inner coffin lid of the priest Nespawershefyt, currently at the Fitzwilliam museum in Cambridge. The coffin was then varnished, sealing in the fingerprint. Source here
- 1300 BC – Clay tablets found in the Minoan city of Knossos show visible finger- and palm-prints, identified as being from the scribes as well as the labourers who created the tablets themselves. The fingerprints would have been created when the scribes and labourers gripped the wet clay, which then dried and hardened. Source here
- 80000 BC – In this dim and distant past era, a Neanderthal is thought to have created a tool by sticking a knapped stone head to a wooden handle using wood tar as glue. This pressure of sticking one onto the other created a fingerprint, which was then preserved as the wood tar fossilised. Source here
Removing your fingerprints is very difficult
Removing your fingerprints has been a staple of crime fiction for years.
However, it is almost impossible to do so permanently because the pattern of your fingerprints is more than skin-deep, and the efforts people go to may inadvertently create much more recognisable fingertips during to scarring!
Palm and sole prints can also be used to identity people if fingerprints are unclear.
Your fingerprints can reveal what drugs you’ve taken
A company called Intelligent Fingerprinting, which is connected to the University of East Anglia, has developed a fingerprint-based drug test. The technology can detect the presence of a number of illegal drugs, including opiates, cocaine and cannabis from just one fingerprint sample.
The test takes less than ten minutes, and uses the sweat found in a fingerprint the measure drug traces. It is non-invasive compared to other forms of drug testing, such as saliva or urine collection.
The fingerprint-based test even works on dead bodies, and is being used by coroners to help investigate cause of death.
Studies have shown that 13% of participants, who had never used any of the drugs involved, have fingerprints which are contaminated with drugs such as cocaine. Cocaine is well-known to be present on many bank notes, but this high result still surprised the scientists.
However, they were able to set a cut-off point which could distinguish between accidental environmental exposure and actual drug usage, so there is no need to be concerned about false positives with this new technology.
Tensor plc is a UK based, award winning, market leader in designing, manufacturing and installing security, access control, attendance monitoring and energy management solutions.
We provide biometric readers which use employees’ fingerprints for maximum security and certainty of identification.