What are these lines on our fingers and what are for?
All our fingerprints are different! Fingerprints are formed before we are even born and are influenced by our genetic code – the special instructions in your body that make you YOU!
Did you know the study of fingerprints is called “dactylology?” – sounds kind of like a pterodactyl? That’s because the dinosaur’s name means “feather finger/toe.” Get ready to dive into a whole new “whorld” of learning!
Did you Know??
Chimps, apes, and koalas all have fingerprints too- and prints from koalas are so similar to humans’ that scientist can’t always tell them apart.
In this activity, you will categorize your fingerprints and make a design with them.
Identify the different types of fingerprints
Use fingerprints to make an art design
Fingerprints, genetic code
- Fingerprints are made up of a series of ridges, called fraction ridges.
- Each of the ridges contains pores which are attached to sweat glands. The reason you can see fingerprints of various surfaces, like glasses, is because of this sweat.
- Finger prints are unique – no two people have been found to have the same fingerprint. The chance that someone has a fingerprint that matches yours is one in 64 billion.
- Even identical twins who share practically the same DNA have different fingerprints from one another.
- A person’s fingerprints are formed when they are a small developing fetus during the mother’s pregnancy. Pressure on the fetus’ fingers causes the folding in the skin layers that forms the ridge patterns we see on our fingers today.
- Fingerprints come in different shapes:
- loops (curves beginning on one side of the finger and ending on the other),
- whorls (circular or spiral patterns), and
- arches (which slope upward then down, like a small mountain).
- Genetics play a role in determining the pattern of ridges in fingerprints. Often the size, shape, and spacing of ridges are influenced by DNA. However, developmental factors, such as the environment inside the womb, can affect the fine details of fingerprints. That’s why some family members may have the same shape of fingerprints, but even twins have different fingerprints.
- There is a rare genetic condition called adermatoglyphia that causes people to be born without fingerprints.
This information and more from NIH, Bailey, R. (2019) and Davidson, L. (2008).
Kid Friendly Language
- Fingerprints are the tiny, sometimes swirly lines on the tips of your fingers.
- Everyone’s fingerprints are different, even twins’.
- Part of our fingerprints comes from our DNA – the instructions in our bodies that make us different from everyone else. That’s why you and your parents or brothers and sisters might have the same shape of fingerprints (but your prints will still be different no matter what!).
- Fingerprints form when we are very tiny babies in our moms’ stomachs. All of the forces in her belly that are pushing on the baby’s fingers make the ridges form.
- Fingerprints never change throughout a person’s life (although fingerprints can be damaged from trauma like burns)
- Since we all have unique (“different”) prints, any fingerprints left on items at a crime scene can help police officers figure out who was there.
- Scientists don’t know exactly why humans develop fingerprints. For a long time, it was hypothesized (guessed, theorized, or explained) that fingerprints helped us hold objects better – but studies haven’t found that to be true. Now researchers think fingerprints might help protect our fingers or increase sensitivity.
- Baby powder
- Clear tape (packing tape works great)
- Black card-stock or construction paper
- Recommended: magnifying glass
- Optional: protective smock, work space covering such as newspaper or washable tablecloth
- Connect to prior knowledge:
- Ask: Have you ever looked really closely at the ends your fingers? What is on them? What observations can you make?
- Explain: Those lines are called fingerprints! Everyone has different fingerprints and they are formed when we are still in our mom’s stomachs. Scientists don’t really know why we have fingerprints, but there are some hypotheses (guesses).
- Ask: Can you think of any reasons humans might have fingerprints? How could we test those theories?
- Spread a small amount of baby powder onto a plate, ensuring there is a thin layer at least the size of a quarter.
- Cut or tear a piece of tape large enough to cover a fingertip (about 1×1 inches) and lay it on the work space, sticky side up.
- Apply a small amount of lotion to one finger – the forefinger may be the easiest to start with, but all our fingers have prints to use!
- Carefully place the fingertip with lotion onto the baby powder, ensuring there is a thin coating on the surface of the finger.
- Gently place that finger onto the sticky side of the tape and peel it off.
- Flip the tape over and stick it to the black card-stock, gently pressing the fingerprint down.
- Carefully peel the tape off, leaving the baby powder design on the card-stock.
- Reveal the fingerprint and use a guide to assess what shape your fingerprints are. Try it with all your fingers!
- What kind of fingerprint did you have? Were you surprised?
- Possible Responses: Responses will vary.
- Try the activity with different members in your family. Are all your fingerprints the same shape?
- Use fingerprints to make artwork. We love using Ed Emberley’s fingerprint books for inspiration, such as this one.
- There are lots of ways to take fingerprints, outlined here. Test different ways and see which one makes the best print.
- Have groups of children compare their fingerprints. How are they the same and how are they different? Graph the numbers of students who have each type of print.
- Ask parents if they have any finger or footprints taken when students were newborns. Students could even remake footprints and compare to the ones from when they were a baby – showing how fingerprints never change.
- Learn about how crimes are solved! Take a virtual tour of a forensic biology lab here, play some online games here, and check out some games in the FBI Archives here.
Check It Out!