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Dr. Uner Tan on Reverse Evolution in Humans

by Sultan Tarlacı (2010-11-10)


In 2006, the world of science was stunned by the discovery of a Turkish physiologist Dr. Uner Tan who found that a few families in
Turkey consisted of members who could only move on all fours. After scientific examination and studying them, Dr. Tan concluded that these apparently disabled individuals were examples of “Reverse Evolution in Humans”, i.e. the ancestral trait of quadrupedal motion had genetically reappeared in them. This groundbreaking discovery is now termed as “Uner Tan Syndrome” and has culminated the research going on for years on the possibility of reverse evolution in nature. More recently, it has discovered that a single mutation can cause this condition in a family that otherwise would appear and function normally. Having interviewed Dr. Tan before for The Audience Review, I had another brief e-conversation with Dr. Tan the other day about his research.

Ernest: Dr. Tan, thanks for joining me at World New! First, please tell us what were your views about reverse evolution prior to studying the Turkish families affected with the Uner Tan Syndrome?

Dr. Tan: Actually, I was not aware of reverse evolution when I discovered the individuals walking on all four extremities in 2005. Before that, I had only been reading and thinking about the theory of evolution as an enthusiastic scientist. The idea of reverse evolution was just a flash, an ‘aha’ experience, without conscious thought, that came to me as I first saw them. My mind was in a chaotic state of high level excitation when I suddenly realized they were exhibiting the walking style of our ape-like ancestors. I called it “backward evolution” when I used the conscious verbal expression. Thus, the subconscious processes apparently ended in the emergence of a novel hypothesis.

After neuropsychological and radiological examinations, I prepared two articles about these cases, and named the syndrome “Uner Tan syndrome” following the suggestion of my English colleagues. As these articles were published, Jack Lucentini, the editor of World Science, reported the novel syndrome and backward evolution, which was found to be plausible and testable by a US biologist, and some paleontologists, despite some controversy. Nevertheless, this step opened a new area in my search for the quintessence of human beings.

I know now that the reverse evolution has been proven even in animal experiments. Nevertheless, I was the scientist who first suggested the existence of reverse evolution in human beings, consistent with the definition of backward or reverse evolution. That is, “the reacquisition of the same character states as those of ancestor populations by derived populations” (Teotonio and Rose).

Ernest: And what were the compelling evidences to convince you that it was reverse evolution rather than some physical disability accompanied by mental retardation?

Dr. Tan: There are many cases of individuals with similar physical disabilities with or without mental retardation and truncal ataxia, but they do not use quadrupedal locomotion. I have discovered reverse evolution (reacquisition of any ancestral trait) not only in the individuals with brain damage and mental retardation, but also in some individuals who exhibited facultative or habitual quadrupedal locomotion despite having entirely normal brain and cognitive abilities. These provide compelling evidence for a reverse evolution in individuals with normal brains, suggesting the role of adaptive self-organization for the emergence of a motor behavior.

In this context, the contemporary theories of motor development accentuate the role of self-organization as a holistic process, which occurs in dynamic systems that have very large numbers of interconnected elements during infantile development, without previously established neural code or any other motor program. Rather, a motor behavior such as locomotion may be the result of dynamic interaction of contributing subsystems such as genetics, central pattern generators, joints, posture, balance, body constraints, muscle strength, extensor and flexor motor systems, perceptual processes, cognition, motivation, environment, hormonal system, etc. Therefore, the output of the developing locomotor system may result in unpredicted behavioral patterns, including the reappearance of ancestral traits. The evolution itself may also be considered as an adaptive self-organization.

Ernest: How do people with Uner Tan syndrome differ genetically from other humans, which we call normal individuals?

Dr. Tan: All of the individuals exhibiting Uner Tan syndrome belonged to consanguineous families, that is, the father and mother were close relatives, suggesting that an autosomal recessive transmission may be responsible for the syndrome. If so, there ought to be a genetic mutation contributing to human quadrupedalism and reverse evolution. Accordingly, we succeeded in discovering the genetic mutation associated with Uner Tan syndrome and possibly reverse evolution. We have also succeeded in publishing the results in the Proceedings of the National Academy of Sciences of USA (PNAS), which was the first article on genetics solely from Turkey. The Editor of this journal, Mary-Claire King wrote “Human molecular genetics in Turkey is ‘on the map’ with this elegant analysis.”

Recently, we have also discovered another gene in another family, responsible for the Uner Tan syndrome. An entirely new technique was used in the genetic laboratories of Roche, to identify the gene for the syndrome: Roche reported this great discovery to the world scientists in a media release with the title: “Researchers solve mystery of Uner Tan syndrome with targeted next-generation sequencing using Roche NimbleGen sequence capture.” Till now, the cause of this disorder in the original family remained unclear. Now, a single mutation was discovered as the genetic basis for Uner Tan syndrome in the affected family. This study will be published shortly. In summary, as originally proposed, a single mutation was responsible for the syndrome and evolution in reverse.


Ernest: So is Uner Tan syndrome solely genetic, or are there environmental factors that contribute to its development in affected individuals?

Dr. Tan: It seems that genetics play a major role in the origins of Uner Tan syndrome. Concerning the environmental factors, most of the families lived in small villages, but not all of them, since one family lived in a big city. Most of the individuals belonged to poor families, but there was one rich family. All of the families were religious and believed that “God gave them to us”. One of the relatives of one family was a physician and attempted physical treatment of the affected children, but without success. The mother forced her quadrupedal daughter to walk upright for six years, but without success. The landscape they lived in was not rough enough to force them to walk on all fours. These results suggest that socioeconomic and environmental factors are not primary in the development of quadrupedal locomotion and mental retardation.

Ernest: Has any case of Uner Tan syndrome been reported in any other human individual or group of people besides those you studied in Turkey?

Dr. Tan: Yes. Some cases exhibiting Uner Tan syndrome have been found in places other than Turkey, but rarely. These countries are Iraq, Argentina, Chile, and India where one family has been reported in each country.

Ernest: So are your subjects being treated for the disability associated with Uner Tan Syndrome?

Dr. Tan: The individuals exhibiting Uner Tan syndrome have been using parallel bars to learn upright walking every day since 2005, but without the slightest improvement. In one family, a physician who was a relative of the children with Uner Tan syndrome, tried to treat the quadruped individuals also using parallel bars, but with no success. The mother of a quadruped daughter fastened stones to her legs for six years to make her legs stronger so she would be able to walk upright, but again without success. Moreover, some individuals have also been given crutches but without success, and they prefer quadrupedal locomotion. So, any physical treatment seems to be unable to improve the ability to walk upright in these individuals.

Ernest: Going back in time Dr. Tan, there were some news of controversy with some British researchers, if I remember correctly, over studying the affected Turkish families. Do you mind telling a little about it?

Dr. Tan: I’d prefer not to talk about it because as a scientist I prefer to communicate with publications rather than get involved in slanging matches and gossip. Basically, some British scientists came to Adana supposedly to meet the families, but actually to make a documentary they then sold to the BBC and which contained false claims. I had concerns about some of their later behavior and false claims also, and reported these to the Turkish Academy of Sciences’ ethics committee. Their claims were incorrect, and that’s all I’d like to say about it.

Ernest: Understandable! What are your current research projects mainly about?

Dr. Tan: Discovering novel families with members exhibiting Uner Tan syndrome, further analyzing the genetics of this syndrome, and studying the mechanisms of human quadrupedalism with regard to the evolution of the human brain.

Ernest: Many Thanks Dr. Tan for your precious time and sharing your knowledge!



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