MadSci Network: General Biology

Re: Why are there lines on my palm?

Date: Mon Mar 21 19:36:40 2005
Posted By: Jen Baucom, Faculty, Lower School Science Lab Teacher
Area of science: General Biology
ID: 1111041867.Gb

Hi RN,

You've asked quite an intriguing question - believe it or not, those lines on your palm are related to fingerprints, and can be used to indentify people just as fingerprints can. They are unique to each individual, and are called palmar flexion creases. Even identical twins don't have the same patterns of palm creases! Palmar (or palm) creases form by the 3rd month in utero on a fetus, and like fingerprints, never change (unless there is permanent scarring of some kind) until the decomposure of the skin at death. Both fingerprints and palm creases are found on the padded side of the hand, a volar area (which means either the palm of the hand or the sole of the foot). The bottoms of your feet are also volar areas, and the creases and patterns found on the skin on these parts of the body are types of friction ridges. Since humans originally walked on all fours, we can see that friction ridges once helped humans get a grip on what they were walking on!

Even today, imagine the difficulty of holding a slippery glass of water with totally smooth plams and fingers (almost as if you were wearing a slick rubber glove!). Each human has 3 palmar creases per hand, except in some cases of congenital defects or disease. The one that loops down around the thumb area is called the longitudinal radial crease. The 2 going partway across the palm are each a type of transverse crease. Some people non- scientifically refer to these 3 creases as the "head, heart, and life lines". People with genetic defects often have an abnormal pattern of palm creases; for example, in many Down Syndrome individuals, both transverse creases may be fused together to form one long crease across the entire palm. Forensic scientists sometimes use palm creases when evaluating criminal cases (for example, a bloody palm print found on a wall). They believe that palm crease patterns are a valuable way to identify individuals, just as much a fingerprints are. There is, however, still some debate over the accuracy of this means of identifying criminals.

The study of skin ridges is called dermatoglyphics, which literally means "skin carvings". If you are interested in learning more about palmar creases, or the study of dermatoglyphics, you may want to check out some of my references below. Thanks for your intriguing question!

-Jen Baucom, MAD Scientist,10987,900940,00.htm

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