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Posted on Wednesday, January 17, 2001 - 10:27 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Many factors affect individual friction ridge (fingerprint) shape and path. Developmental stress and other environmental factors in the womb cause unlimited variety in friction ridge formations.

In expert testimony summarized on page 6 here, Dr. William Babbler explained why all friction ridge skin is different:
"...environmental factors, including chemicals taken into the body, the differential growth and development of the bones in the hands, and the actual dimension of the bones themselves contribute to the variation noted in the friction ridge skin."

Fingerprint experts think of friction ridge detail in three levels. If you were to compare these to levels of detail describing a zebra, the three levels might be as follows:
Level 1 could be an outline image with enough detail so that from the general shape or pattern it appears to be a zebra. From this level of information, you can eliminate giraffes and cows, but you are not going to identify an individual animal.

Level 2 might be an image showing more detail. From such an image, you can eliminate all horses. The length, direction, and intersections of the stripes can be seen, but this image does not clearly show the width and shape of individual stripes. You might be able to identify a specific zebra from another photo if the stripes are clear (sharp) enough and if enough of the same area of the zebra shows.

Level 3 would be similar to a good quality photograph. From even just this partial photo of the zebra, you cold compare the fine details of the stripe shapes and paths to identify the specific animal.

The Level 1 detail shown above (overall shape and size) is affected by inherited traits from the zebra's parents. The stripe formations at Level 2 and 3 are different for each zebra.

The overall general flow or pattern (Level 1 detail) of friction ridges on human hands and feet is governed primarily by the height and position of the volar pads on the unborn child's hands, and the formation of the volar pads is affected by inherited traits from the parents. High pads will form whorls, low pads arches, a medium height pad to one side a loop, etc. Thus twins or close relatives may have very similar ridge flow patterns (also called fingerprint classification).

The length and ending point or intersection (Level 2 detail) and also the individual shape of ridges (Level 3 detail), including the location of sweat pores, are different for each person due to developmental stress and differential growth before birth. Thus twins and all other persons have different finger, palm, toe and foot prints when you look beyond just the general pattern of ridge flow.

Click here to see some examples of of Level 1, 2 and 3 friction ridge detail.

Click here to read David Ashbaugh's Ridgeology publication about friction ridges, including pictures and detailed information about the development of friction ridges. (This is a pdf file and may take a couple of minutes to open in Adobe Acrobat if you are using a telephone modem.)
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Posted on Wednesday, January 17, 2001 - 07:24 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

I am doing a science project on fingerprinting and was wondering whether you would be able to answer this question.

I was just wondering whether you knew why every fingerprint is different?

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