Random Event

[Charles Parker]

It has been said that the formation of ridge structures, features, etc. are random events.

Is it possible that they are not random events but formed from "Non-Linear Phenomena" or "Dynamic Instability" or what is commonly called today---Chaos Theory?

What are your thoughts?

[Pat A. Wertheim]

The word random is not entirely appropriate. The patterns are a function of volar pad structure, timing, and stresses. The individual ridge events we refer to as "points" are formed during early embryological growth as ridges are formed and pulled apart and new ridges form between them to fill in the expansion areas. The best information is in the work of Dr. William Babler, who testified at the first Daubert hearing on the admissibility of fingerprints in 1999. He did extensive research into the development of patterns and ridges. Off the top of my head, I don't remember where to find his work online. Anybody else?

[Kasey Wertheim]

Off the top of my head, I don't remember where to find his work online. Anybody else?

It is sort of difficult to find, but in the "Reference" section of the site, go to the third link down (dealing with skin formation and embryology) and there is a page devoted to Babler:

http://www.clpex.com/Information/Babler ... ticles.htm

-Kasey

[Gerald Clough]

Well, I agree "random events" is wrongly used. Examination of a system must, of course, limit the bounds of the system to something less than universal totality. Therefore, there is an initial state. Without being all that much of a mathematician, I would guess development of ridge detail does indeed seem to be a likely candidate for a nonlinear dynamical system. If I have a reasonably proper feel for these systems, I look to the fact that the results of development of ridge detail are apparently bounded. We recognize results that are within those bounds. (We immediatley see that a fabric mark is not a fingerprint.) We would immediately recognize a result that fell well outside what we would accept as one reasonably likely to be a set of human ridge detail.

In the end, probably the best we can say is that, development is only "random" (in the vague sort of common usage), because, being the product of a nonolinear dynamical system, the result is unpredictable, except to limiting the bounds of the end state. Is anything really random?

Look at both the text and diagram of a "bifurcation" on page 16 of:
http://www.ziaspace.com/elaine/chaos/Ch ... Theory.pdf

And look at the Ikeda 16X strange attractor:
http://hypertextbook.com/chaos/eyecandy/ikeda.03.html

[Charles Parker]

The word random is not entirely appropriate.

If the word “random” is not entirely appropriate, what word or phase is ?

Babler’s work and others in the development of friction ridge detail is a valuable work that needs to be a part of each Latent Print Section Library.

However my point was not direct enough. I think over the years I have a good concept of when the friction ridges were formed. I think I have a fair concept of how they are formed. For now I am curious as to the “Why”. When the stresses of growth form new events, “why” at that point and not a few hundred cells to the left or right, up or down.

Someone might say “Well Charles, that is the area of greatest stress or pressure”. OK, but why the greatest stress or pressure at that particular point.

Chaos Theory has been used to describe the branching of a tree, or the branching of the lungs. Why not part of the random events in the creation of friction ridge detail?

I think some of the following might be an answer (just speculating). These are from
http://www.imho.com/grae/chaos/chaos.html

------, common to chaos theory, is also known as sensitive dependence on initial conditions. Just a small change in the initial conditions can drastically change the long-term behavior of a system. Such a small amount of difference in a measurement might be considered experimental noise, background noise, or an inaccuracy of the equipment. Such things are impossible to avoid in even the most isolated lab. With a starting number of 2, the final result can be entirely different from the same system with a starting value of 2.000001. It is simply impossible to achieve this level of accuracy - just try and measure something to the nearest millionth of an inch!

Fractal structures have been noticed in many real-world areas, as well as in mathematician's minds. Blood vessels branching out further and further, the branches of a tree, the internal structure of the lungs, graphs of stock market data, and many other real-world systems all have something in common: they are all self-similar.

Researchers discovered a simple set of three equations that graphed a fern. This started a new idea - perhaps DNA encodes not exactly where the leaves grow, but a formula that controls their distribution. DNA, even though it holds an amazing amount of data, could not hold all of the data necessary to determine where every cell of the human body goes. However, by using fractal formulas to control how the blood vessels branch out and the nerve fibers get created, DNA has more than enough information. It has even been speculated that the brain itself might be organized somehow according to the laws of chaos.

Chaos theory attempts to explain the fact that complex and unpredictable results can and will occur in systems that are sensitive to their initial conditions

For me the simple explanation of Chaos Theory is disorder within order. Also do not think of the pattern as one system, but the ridge fields that make up a pattern are also systems within a system.

Here are a few definitions of “Random”. I personally like the second one.

The word random is used to express lack of purpose, cause, order, or predictability in non-scientific parlance. A random process is a repeating process whose outcomes follow no describable deterministic pattern, but follow a probability distribution.
en.wikipedia.org/wiki/Random

Random means an uncertain or equally probable choice or outcome, without pattern and
dictated by chaos or chance. www.eubios.info/biodict.htm

I think “random” is a good word for the formation of ridge events. At least until a better one comes along.

As I said just speculation from a curious mind.

[Gerald Clough]

So, I'll back up and accept "random." It has the virtue of not bogging the explanation down in mathematical and philosophical issues. Chaos is deterministic. It is useful in the study of systems such as we are discussing. But we would find it difficult to define the bounds of the system, and so we can't identify the external influences. That's okay. The hallmark off chaotic systems is the input of undetectably small variations in initial conditions. It kind of comes down to the notion that actual randomness may not be a feature of this universe, the point of hidden variable theory versus quantum mechanics. Therefore, our "random" can only refer to the product of a chaotic system, and the word is then used correctly here, not with exactly the meaning folks imagine, but exactly descriptive of the sort of phenomena to which they refer when they us it.