If you have ever looked down at your hands you may have noticed little patterns on your fingers. If you like crime shows or true crime podcasts you of course know these are your fingerprints. Ever person’s fingerprint is unique and is based on their genetics. While in the womb, as the fingers are developing, sections called volar pads form. These swell (looking like they are bubbling out like bubble wrap) in different areas of the fingers, hands, and feet. Sometimes they are center, some are off to the left, while others are all the way at the top. These locations are determined by genetics predetermined by the fetus’ DNA sequence.

As the hands grow, not all parts or fingers will grow at the same rate. Sometimes the left side of the thumb may grow a bit faster than the right, causing a slant. The fingerprints will then slant more to the left when they are fully developed. This also determines what the shape will look like. This is why types of shapes (loops, whorls, arches) will actually be similar in families. (See SciShow – How Do My Fingerprints Form? for more information and description.)

There are also smaller details besides the shape of the print called minutiae. This can include things such as the viscosity of the amniotic fluid, the position of the fetus, or even the movement of the fetus in the womb. These factors can determine the friction ridges, furrows, and where the fingerprints connect and diverge. This is why identical twins will have some differences in their fingerprints when you look closer than just the shape.

Key Terms

Fingerprints
Pictures available here: http://www.forensicsciencesimplified.org/prints/p...
Loops – points that curve back on themselves to form a loop shape
Whorls – circular patterns, like tiny whirlpools
Arches – create a wave-like pattern
Genetics – the hereditary properties of an organism based on their DNA sequences
Volar Pads – the swelling of tissue (called the mensenchyme) underneath the skin layer (epidermis) on the surface of the hands and feet of a developing human fetus.
Minutiae – non-genetic environmental factors that determine the shape of fingerprints
Friction Ridges – Raised sections of fingerprints
Furrows – indented parts of fingerprints

Supplies

- Graphite Pencil (Wooden or Mechanical)

- Scotch Tape

- 1 Piece of Paper (any color, white works best)

Step 1: Take the Pencil and Make a Dark Mark on Part of the Paper. the Darker and More Graphite Placed Onto the Paper, the Better!

Step 2: Take a Small Piece of Tape and Either Keep It on the Dispenser, Flipped Upside Down, or Slightly Attach to the Edge of a Surface (such As a Table).

Step 3: Take Your Finger With the Graphite and Place the Tape Over It to “lift” the Fingerprint.

Step 4: Remove the Tape From Your Finger and Place It Onto the Paper.

If desired, label which finger it is and repeat with all other fingers. If also desired, compare and contrast the fingerprints of family members to see what traits are passed on through the family.

Step 5: Further Exploration

MinuteEarth – Why Are Your Fingerprints Unique?

https://www.youtube.com/watch?v=iCRy8voU5dE

SciShow – How Do My Fingerprints Form?

https://www.youtube.com/watch?v=WZL7OpFq0fw

SciShow Kids – See Your Own Fingerprints!

https://www.youtube.com/watch?v=cZKGpg_fttw