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Letters to the Editor--—
But the Monkeys are Really Only In their recent article in “The Print”1 Brandon, Egli and Unander compared palm and fingerprints from two rhesus monkeys (Neti and Ditto) that had been produced using a procedure called nuclear transfer technology. They found that the fingerprints were “remarkably similar but not identical”. From human studies this result is not surprising even if these animals were indeed identical twins or as the authors claim “genetically equivalent to monozygotic twins.” In their conclusions Brandon, Egli and Unander pose the question “Could the fingerprints of these two nuclear transfer created twins be the same?” After reading the Web page from the Oregon Regional Primate Research Center (ORPRC) it is clear that Brandon, Egli and Unander have incorrectly stated or inferred the true relationship of these animals. Even the title “ `Cloned' Primates and the Possibility of Identical Fingerprints” is misleading. Furthermore, careful reading of Brandon, Egli and Unander's article should bring questions to the readers mind as to the true relationship of these two animals. At best Neti and Ditto are siblings and not identical twins or “genetically equivalent to monozygotic twins” (identical twins are animals conceived from a single egg and a single sperm which, once united, splits at some point early on during embryonic development to create two animals with identical nuclear DNA). The animals at ORPRC, a female and a male, are genetically equivalent to dizygotic twins (animals conceived from two separate eggs and two separate sperm) and are normal (not identical) siblings. One of the obvious genetic differences is the fact that one is male and the other is female. From their Web site2 Don Wolf et al. at the ORPRC report the following circumstances surrounding their work: 1) “The research team separated cells from each of several embryos that had been created by fertilizing eggs collected from a first monkey. 2) They then fused some of those cells with `shells' made by removing chromosomal DNA from eggs harvested from a second monkey and finally 3) transferred these new embryos to surrogate monkey mothers.” Plainly stated in their Web page “Neti and Ditto were siblings rather than identical twins because cells from several embryos had been used in creating the transfer embryos.” Pedigree analysis by ORPRC shows that there is indeed one genetic “father” (one sperm donor) and one genetic “mother” for Neti and Ditto. Being siblings means that Neti and Ditto share, on the average, only one fourth of the same DNA by descent. Brandon, Egli and Unander also make an argument that the same environment during embryonic and fetal development may contribute to similarities in fingerprints. Note that Neti and Ditto had two different surrogate mothers and therefore had different embryonic and fetal environments. This means that Neti and Ditto have more differences environmentally (as far as embryonic and fetal development is concerned) than even regular siblings. It is interesting to see whether two sibling rhesus monkeys created through nuclear transfer technology have different fingerprints. However, it is clear that these animals are not genetically identical to monozygotic (identical) twins. Neither can they actually be considered dizygotic (non--identical) twins since they were born to two different surrogate mothers and they were created from two separate embryonic nuclei. Any conclusions drawn from the work of Brandon, Egli and Unander should be evaluated with these arguments in mind.
by Daniel J. Gregonis, Criminalist
1 Brandon, M., Egli, K. and Unander, A. (1997) “Cloned” Primates and the Possibility of Identical Fingerprints. The Print. Vol 13, No. 5. pp. 1--5.
2 www.teleport.com/~orprc/current/net.htm (Editor— I appreciate Mr. Gregonis's letter, as it has stirred additional discussion and thought. However, he indicates that the title was “misleading” in its use of the term “Cloned,” when the authors did explain the “misleading” usage of the term by clearly announcing that “despite the misleading media term used that the monkeys were cloned, ...” and, I wonder how many of us would have recognized the subject or been interested in it, if the title had been Nuclear Transfer Technology ...? Often, common terms like “latent” or “DNA fingerprinting” are misused or used inaccurately to provide a common understanding or link to a recognized field. Mr. Gregonis also questions the genetic relation of the primates indicating “that at best Neti and Ditto are siblings and not identical twins or genetically equivalent to monozygotic twins.” However, a press release from the ORPRC (dated 19 May 97 by Dr. James Parker, Public Information Officer, profiling the nuclear transplant procedure that produced Neti and Ditto), refers to them as being “genetically indistinguishable `monkeys.' ” The authors used the term “genetically equivalent” (meaning equal in force, quantity, value or meaning) to differentiate from truly genetically identical or monozygotic/identical twins. However, as David Ashbaugh stated in a discussion about this paper “these are minor issues at this point in educating friction ridge examiners about basic scientific issues that they all should understand. Mary et al, explored a very important part of that required knowledge.” The authors should be commended and encouraged to further their work in this area. As editor, I wish to encourage them, and others, to explore at deeper levels the sciences on which our science is based.) Cloned Primates and Identical Fingerprints (This correspondence was originally sent to Mary Brandon, one of the authors of “Cloned” and is reprinted here with permission of both parties.) I just thought I would drop you a line telling you how much I enjoyed reading your paper. It is good to see fingerprint examiners exploring the scientific side of the discipline. The key to your quest is found in the manner in which friction ridges form. The basic ridge formation is a small area of ridge containing one pore -- a ridge unit. These ridge units start to grow independently with a mandate to form rows or islands as Hale calls them. The overall flow of the ridge units or pattern is dictated by the shape of the surface they are growing on. During the initial formation of the ridge units there are swellings on the volar areas called volar pads. These are supposed to be the remnants of walking pads. The size and shape of these pads may be affected by hereditary forces. Therefore, closely related people, such as clones who have the same DNA, stand a good chance to have similar patterns. Various forces of growth may alter patterns, even with clones, as is our experience with identical twins. Primates tend to have whorl patterns due to the fact that they have large concentric volar pads. Geneticists tell us that they have not evolved as far as humans -- ?? All things in nature are subject to some form of differential growth. In the case of fingerprints, it is at the ridge unit stage where this takes place. Through the volar pads, heredity may dictate that a row of ridge units will curve in a specific arc but it cannot dictate which ones will fuse together to form long and short islands, or which ones will form on the side of or attached to already forming ridges, bifurcations. It is this lack of control of how the ridge units will fuse together that causes the randomness in specific ridge paths and makes specific friction ridge patterns unique. Hale describes two formations in the friction ridges. One he refers to as an island. The smallest island has one ridge unit or a ridge dot. It has one pore. Longer island have more units. We tend to jump around on ridges during comparison and most of the time we do not recognize the long islands. If we followed several ridges from one end to the other we could relate the ridge endings to each other and see the longer island. The longest, of course, start outside the visible print area and end outside so we do not see either end. The other formation Hale describes is the branching which we call a bifurcation. These form on the side of forming ridges. All other ridge characteristics are a combination of these two formations. Ironically, in the same PNWDIAI Examiner was an article by David Stoney -- Fingerprint Identification: Craft or Science [see page 3 of this issue]. Obviously, fingerprint identification is both. There is ample science to defend what we do which can also be used to explain why we do things in a certain way. It is also a craft in that some people are simply better at it than others, possibly through advanced training or innate skills, at comparing and describing the identification process and the areas of science friction ridge identification that it is based on. Stoney's probability hang-up can be solved by establishing a probability factor on the chance of ridge units fusing. He, like most other people in the past with limited knowledge of friction skin, read fingerprint books as opposed to scientific journals and attempted to create a probability model based on ridge characteristics as opposed to ridge units. Ridge characteristics are not a constant, therefore to create a probability model which includes them one must include an arbitrary factor for how many ridge characteristics there are in a fingerprint. Ridge units on the other hand are constant. There are approximately 2600 per sq. in. of friction skin. I called Stoney a few years ago and asked him to rethink his model but he hasn't done so yet. The other area that Stoney does not address is clarity. The premises of identification are based on friction skin which is a three dimensional formation. We identify friction ridge prints which are two dimensional. Clarity is about how much of the detail made it from the original product into the print. If a great deal of the detail is present in the print, it is clear. If little of the detail survived, it is not clear. When we compare prints, the brain considers these shapes even though most people are not trained to address or describe the value of the smaller shapes. It is unfortunate, because identification is all about shape recognition. When the above is understood one suddenly realizes that any probability factor is only relevant to the one print being considered. As clarity changes so does the probability factor. Stoney also compares us to the science of DNA. We are far beyond the level of DNA as a science. During DNA comparison they compare a chemical representation of DNA. There is no level of clarity to assess. In fact, the markers in the gel are sort of fuzzy spots that may be considered in agreement if they are close. I suppose some scientists are better at that craft, reading spots, than others. I wonder if DNA is a science or a craft? DNA scientists must depend on numbers to defend themselves. Their science will mature when they can differentiate between clones. On the other hand, a friction ridge print is a physical reproduction of the 3D print in 2D. Clarity is an issue and the value of shapes in the print fluctuate based on that clarity. Fingerprint scientists express their conclusions based on a volume of unique shapes present and in agreement. They simply are eliminating anyone else as a possible donor -- due to the amount of detail present. Clarity and the amount of detail present are tied tightly together. The size of the print is irrelevant. I suppose one of our problems is that most of us do not have PhD's and therefore mainstream science tends to look down on our efforts. They look over their shoulders and do not see us in the race carrying our diplomas, so they think we are way behind. If they turned their heads forward and look ahead very carefully they may just see our butts in the distance. Our current challenge is to ensure that all fingerprint examiners have the knowledge and ability to describe the issues I have mentioned and many more. While our science is mature and based on solid science, we have done a poor job ensuring that this information is available to everyone. You referenced the ridgeology paper in your article, which is a tough read and difficult to grasp as it was meant as hand out material for a four hour lecture and many topics are just mentioned. Many of the answers to your questions about differential growth can be found in the papers contained in the bibliography. If anyone is interested, I have a book, in draft form, that I hand out at my training courses entitled Quantitative--Qualitative Friction Ridge Analysis. It covers the scientific basis and the evaluative identification process. I sell it at cost, $20.00 US plus $5.00 shipping. If you would be good enough to pass on my enjoyment of your article to your co--authors, I would appreciate it. I hope I didn't get carried away with the above. I find it difficult to talk about only one topic in friction ridge identification as they are all so interconnected. Addressing one issue begs an explanation about another.
David Ashbaugh
These letters to the editor were printed in “THE PRINT” |