Intern. J. Neuroscience, 118:211–225, 2008Copyright C© 2008 Informa Healthcare USA, Inc.ISSN: 0020-7454 / 1543-5245 onlineDOI: 10.1080/00207450701667808

UNERTAN SYNDROME: REVIEW AND REPORTOF FOUR NEW CASES

UNER TAN

Cukurova UniversityFaculty of SciencesDepartment of PhysicsAdana, Turkey

The aim of this study was to describe additional patients (n = 3) exhibiting theUnertan syndrome (UTS), resident in rural areas of Canakkale. The 8th and 9thfamilies with the UTS, with a total of 16 members affected, have not been previouslycharacterized. A single, non-familial case (Bayramic, Canakkale) occurred duringearly childhood after an infection with a high fever. Three cases of familial UTS werelocated in another village in Canakkale. All cases exhibited the three key symptomsof the UTS: (1) walking on all four extremities, (2) primitive language (onlysounds), and (3) rudimentary intelligence. Magnetic resonance imaging showedmild vermial hypoplasia in the non-familial case, while there was cerebellar andvermial hypoplasia with a flattened cerebral cortex in the familial cases. Dexterityof the fingers was normal. The man from the latter family was fond of dragginga wooden box after fastening a string around his belt. The collective observationsand clinical findings suggest two etiologies for the UTS: (1) genetic, via autosomalrecessive transmission and (2) viral, likely the poliovirus affecting the cerebro-cerebellar structures. At a minimum, vermial hypoplasia is suggested to causefully developed UTS. The subjects could stand upright and even walk bipedally,despite difficulties in balance (ataxia), but they preferred quadrupedal walking.The main difficulty with gait was maintaining a dynamic-asymmetric lateralbalance and initiation of the first step during standing. Apparently, a quadrupedal

Received 28 February 2007.This study was supported, in part, by the Turkish Academy of Sciences.The author thanks Erdem Surek from the Dogan News Agency (Turkey) for introducing the

families presented herein.Address correspondence to Prof. Dr. Uner Tan, Cukurova University, Faculty of Sciences,

Department of Physics, Adana, Turkey. E-mail: unertan37@yahoo.com

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gait in an adult is a developmental regression with absence of the higher controlmechanisms for asymmetric lateral balance during bipedal walking. It is suggestedthat these individuals exhibit ancestral traits; the quadrupedal gait with rudimentaryintelligence and primitive speech resulting from viral infections and/or geneticdamage may cause devolution (reverse evolution), a manifestation of an experimentof nature as well as experimental studies in animal models. The results support thenotion of punctuated evolution, in contrast to Darwin’s theory of graded evolution.Dragging a wooden box using a string wrapped around the belt may also be anexample of reverse evolution with regard to tool making, illuminating the verylong-lasting period before the invention of the wheel. Herein, there has been no intentto insult or injure these individuals affected by the UTS; rather, this is an endeavorto better understand the mystery of human evolution. Go to the publisher’s onlineedition of International Journal of Neuroscience for the following free supplementalresource: video clips.

Keywords bipedality, evolution, genetics, primitive language, quadrupedality,rudimentary intelligence, Unertan syndrome, wheel

INTRODUCTION

The Unertan syndrome (UTS), first described by Tan in 2005, is characterizedby three main symptoms: (1) habitual walking on all four extremities, (2)rudimentary intelligence with no conscious experience, and (3) primitivelanguage. There were 19 siblings in the first family described from ruralsouthern Turkey, 5 of whom exhibited UTS. The father and mother of thefirst family were relatives (Tan, 2005a,b, 2006a). Another large family withintra-familial marriages residing in Adana (also in southern Turkey) was thendescribed (see Tan, 2006b,c). There were three sub-families within this secondfamily, with three members in each sub-family exhibiting the UTS. Magneticresonance imaging (MRI) and positron emission tomographic (PET) scansfrom the affected members of the first and second families have been presentedin a recent article (Tan et al., 2007a). A male individual has been identifiedwho has a variant of the UTS (Tan, 2007). He has but the main symptom ofthe UTS, the palmigrade walking style, which he acquired after an infectionwith poliovirus during childhood. In distinction from others affected by theUTS, he is an intelligent man with well-developed language abilities. Hisbrain appears normal on MRI examination. The last family also resides in arural area in southern Turkey (Tan et al., 2007a). This is a very large familywith intra-familial marriages; there are four sub-families with six membersexhibiting the UTS (Tan et al., 2007b). Thus, altogether 7 families with 15cases of UTS have been discovered.

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Interestingly, all of the aforementioned families with UTS are residents ofsouthern Turkey. The purpose of the current work was to present two additionalfamilies with four members affected with the UTS who reside in northernTurkey. Accordingly, a journalist from Dogan News Agency in Canakkalereported that there are individuals in two rural areas of Canakkale who mayhave the UTS. Upon his invitation, the author visited two villages and foundfour individuals exhibiting the UTS. The present study describes their walkingpatterns, intelligence, and speech characteristics with the use of MRI scans andvideo clips.

METHODS

Participants

The first three cases (eighth family identified) were residents of the Sogutluvillage, Ayvacik, in Canakkale. As is shown in Figure 1, there were no intra-familial marriages. The father of these three cases had five siblings, two ofwhom had the UTS: Muserref Yildiz (65 years of age) and Ahmet Yildiz (62years of age). The mother (Ayse Yildiz) and father (Salih Yildiz) had threechildren; one daughter with UTS died and one living son has UTS. A singlecase (ninth family identified) with UTS, Munip Arslan, was approximately 50years old and lived in Bayramic, Canakkale; he had an illness at 2 years ofage, after which he could not stand upright and began to walk on his fourextremities. There was no consanguinity between his father and mother. Noneof his relatives walked on all four extremities.

Figure 1. Pedigree of the individuals with UTS and their unaffected siblings for the family inSogutlu, Ayavacik, Canakkale. Circles, females; squares, males; slash line, deceased, affecteddaughter.

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MRI

Individuals affected with the UTS were scanned with a Siemens 2.0 T magneticresonance scanner (Erlangen, Germany) using a standard head coil and a T-2weighted coronal and sagittal spin-eco sequence. The individuals were placedon a sliding table so that the surface coil was positioned around the head. Afterpositioning the individuals with the head inside the MRI gantry, the radiologistand technologists left the room. The individuals’ mothers, who helped themremain stationary during the imaging process, remained in the room during thescanning process.

RESULTS

The Single Case in Bayramic, Canakkale

Munip Arslan lived in Bayramic, Canakkale and was approximately 50 years ofage. He had an illness with a high fever when he was about 2 years of age. Afterthat, he could not stand upright and began to walk on all four extremities. Therewas no consanguinity between his father and mother. There were no individualswalking on all fours among his relatives. He could not stand upright and hehabitually walked on all four extremities. He could understand simple questionsand commands. He could not speak, however, except answering all questionswith a few unintelligible sounds. Because of a communication barrier, it was notpossible to measure his cognitive abilities, although he seemed to be impaired.The MRI examination showed a normal brain and cerebellum, except for mildhypoplasia in the cerebellar vermis (Figure 2).

The Yildiz Family in Sogutlu (Ayvacik, Canakkale)

There were two sub-families within the main family that had members withthe UTS. There were no intra-familial marriages. The genealogy of the mainfamily is shown in Figure 1. The filled squares (males) and circles (females)depict the members who had the UTS. The mother (Ayse Yildiz) and father(Salih Yildiz) had a normal, adult appearance. The father had five siblings;one sister (II-2, Muserref Yildiz) and one brother (II-4, Ahmet Yildiz) had theUTS. The mother had three siblings without the UTS; she did not rememberany relatives walking on all four extremities. Ayse Yildiz and Salih Yildiz hadthree children, one son (III-1, Ibrahim Yildiz) and one daughter (III-2), whohad the UTS and died at age four, and one normal son (III-3).

The affected members had MRI scans (Figure 3 for Ibrahim’s MRI) typicalof most of those affected with the UTS. Specifically, there was cerebellar and

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Figure 2. Sagittal MRI scans from Munip Arslan; above, cerebellum; below, vermis.

vermial hypoplasia, especially in the inferior aspects, the cerebellar tonsils wereabsent, and the fourth ventricle was connected to the cisterna magna by a largecanal. Otherwise, all of the cerebral structures, including the corpus callosum,were normal, except for mildly enlarged cerebral sulci.

Interestingly, all of the affected individuals could walk bipedally despitetruncal ataxia. However, all of the affected individuals preferred walking onall four extremities, which was done with ease and without ataxia. Video clip1 shows Ibrahim Yildiz standing upright and walking quadrupedally; he wasfond of carrying a wooden box after binding a string around his belt (Figure 4and video clip 2).

Muserref Yilmaz also preferred walking on all four extremities, althoughshe could walk bipedally despite her profound ataxia. Ahmet Yildiz walked

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Figure 3. (above) and midsagittal (below) MRI scans from Ibrahim Yildiz. Notice the hypoplasiain the inferior cerebellum and inferior vermis.

on all four extremities most of the time, but he could also walk bipedally withataxia.

Finger dexterity was good for everyday activities in all of those affected bythe UTS. For instance Ibrahim Yıldız managed to wrap a string around his beltwith which he dragged a wooden box and Muserref Yildiz habitually wrappedwool string around her fingers (video clip 3). Ibrahim Yildiz used string also.

DISCUSSION

The present report presents the eighth and ninth families residing in two ruralareas of northern Turkey (Canakkale) who exhibit the UTS. The previouslydescribed families are residents in southern Turkey (Iskenderun and Gaziantep).Thus, the UTS is not endemic to a specific geographic region.

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Figure 4. Ibrahim Yildiz preparing the string to drag a wooden box (above) and dragging the boxalong the street (below).

Etiology of the UTS

Genetic Origin. The hitherto reported cases of the UTS suggested that theetiology is primarily genetic. The first reported family resides in Hatay, thesecond family resides in Adana, the third to seventh families reside in Gaziantep,

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and all reported families were known to have intra-familial marriages with theexception of the one family in Sogutlu (Ayvacik, Canakkale) that was presentedherein. The genealogies suggested an autosomal recessive transmission for theetiology of the UTS in all of these families. The genetic defect was shown tobe on chromosome 17p in the affected members of the first family (Turkmenet al., 2006). The genetic analysis of the other families is not yet complete.

Viral Origin. The second cause of the UTS may be viral, hitherto noted intwo patients, one in a village near Adana (Tan, 2007) and another, MunipArslan (Bayramic, Canakkale), presented herein. Interestingly, both of theseindividuals had an illness with high temperatures during infancy (about twoyears of age), after which they were unable to stand upright and walk bipedallyin an upright position. Most likely, they were infected by the poliovirus duringinfancy. These two cases serve as suggestive examples of a viral etiology. Thefirst case had a normal brain MRI with normal cognitive abilities, includinglanguage (Tan, 2007); he was a variant of the UTS exhibiting only the wrist-walking feature of the three hallmark symptoms. The second case was presentedin the present work; Munip Arslan had fully developed UTS with a mild vermialhypoplasia in his brain MRI.

A childhood illness with a high fever may be caused by the poliovirus,which is known to affect the medulla, cerebellar vermis, midbrain, thalamus,and cerebral cortex, in addition to the spinal motor neurons (Bodian, 1949;Baker & Cornwell, 1954). Accordingly, acute cerebellar ataxia has beenreported following a poliovirus infection (Curnen & Chamberlin, 1962). Thus,a defect in the cerebro-cerebellar structures, including the cerebellar vermis,caused by the poliovirus may have been responsible for the occurrence of theUTS in these cases. This defect may not necessarily be visible on MRI scans.

The central mechanisms responsible for the dynamic lateral balance duringupright walking were probably damaged in those patients who had a viralorigin of the UTS. Interestingly, a black macaque monkey in Israel switchedexclusively to walking on her hind legs after a long-lasting illness with a highfever (Boyd & Silk, 2000). Thus, a viral infection may cause an alteration inbrain functioning, resulting in a shift in the walking pattern from quadrupedalityto bipedality or from bipedality to quadrupedality. The switching mechanism forthis possible evolutionary event has not been delineated. It is known, however,that viruses are able to change the genetic material of host cells, altering theexpression of their own genes or those of the host. So, a viral etiology may beconsidered, in the end, to be tantamount to a genetic disease.

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Cerebellar and Vermial Hypoplasia. The MRI scans showed cerebellar andvermial hypoplasa in the affected individuals. There was vermial hypoplasiaalone in the single case acquired after a childhood illness with a high fever. In aprevious study, it was shown that radioactive glucose metabolism during PETscans was nearly absent in the cerebellum of the individuals in whom the UTSwas genetically transmitted (Tan et al., 2007a), although the MRI scans showedpartial hypoplasia in the cerebellum and cerebellar vermis, especially in theinferior aspects. The degree of vermial hypoplasia seemed to be associated withthe degree of severity of the UTS. To cause fully developed UTS, significantvermial hypoplasia seemed to be a prerequisite.

Upright Walking

Most of the individuals affected with the UTS were able to rise from a sittingposition and remain in the upright position as long as they wished. The maindifficulty was the initiation of the necessary leg movement to take the firststep using a leg. Although the cerebellar vermis is responsible for truncalbalance, the lateral balance during walking is different from the simple balanceduring standing (see Hof et al., 2007). Their truncal balance was normal duringstanding and they could even stand upright without any discomfort, but theylost balance if they tried to take a step, transferring the body weight to theopposite leg and stabilizing it in a fully extensor posture. Apparently, there wasno difficulty with the cerebellar control of the trunk muscles. Accordingly,there were individuals walking on all four extremities with no cerebellarhypoplasia evident on MRI scans (Tan, 2007). Munip Arslan (see earlier),who had fully developed UTS, also had a normal cerebellum on MRI scan.Thus, the physiologic mechanisms of bipedal walking during upright postureshould be evaluated in cases with respect to the UTS. However, the neuralmechanisms of gait are very complex and not completely understood at thistime. Concerning the cerebellar system, the neural control of gait is not limitedto the cerebellar vermis or cerebellar control systems; normal gait movementsof the legs are possible with a normal spinal cord without any interference fromthe supraspinal centers. This can be easily demonstrated when a baby is heldupright with the feet just touching the ground. In this situation the baby beginsto move its legs as if stepping, while being unable to balance or support itselfindependently during stepping because the cerebellar and/or vermial systemsneeded to support the body during walking movements of the legs are not fullydeveloped yet.

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Control of the dynamics of asymmetric lateral balance is involved incounteracting perturbations caused by gait movements themselves. Lateralbalance during upright gait may be referred to as “asymmetric lateral balance,”and is instantaneously controlled by the spino-cerebro-cerebellar system inhumans. If one compares quadrupedal walking in individuals with the UTSwith babies who make walking movements when held in the upright position,it can be concluded that the spinal walking movements with legs normallyoccur in individuals with the UTS while walking on all four extremities eventhough they cannot manage the necessary postural adjustments during uprightbipedal gait, thus the problem with asymmetric lateral balance.

Walking on All Four Extremities

Some of the individuals with the UTS can actually walk bipedally in an uprightposture, but they can only maintain asymmetric lateral balance with greatdifficulty. Most of them fall down if they try to take a step. In contrast,all of them walk on all four extremities with great ease, as if it is theirnatural gait. They therefore likely have a preference for the quadrupedalgait, similar to the hand preference. That is, a right-handed man can writeusing the right hand with great ease, contrary to the left hand, which isvery clumsy in writing. Therefore, he may prefer his right hand in writing,and vice versa in a left-handed person. Although preference is a psychologicmanifestation, it has neural mechanisms to facilitate the right-hand actions inskilled movements. Accordingly, a preference for the quadrupedal gait shouldhave neural mechanisms, too. Walking on all four extremities (bear crawling)is quite normal in some children before upright walking. Children walking onall four extremities were described thoroughly as early as 1928 by Hrdlicka,who reported 11 children walking on all 4 extremities for about 8 months andthen standing up and starting to walk bipedally. So, there may be a transitoryperiod during child development in which bear crawling is exhibited. However,as seen in the UTS, some children may prefer bear crawling for the rest of theirlife and continue to walk on all four extremities.

If the individuals with UTS preferred quadrupedal walking because of theimpossibility or great difficulty in performing upright walking, they would do italso with great difficulty, as can be experienced if tried by anyone. As mentionedearlier, the preference should have neural mechanisms whether it be a handpreference or walking preference. However, the neural mechanisms involvedin quadrupedal walking in apes and humans are not known. Apparently, theadult quadrupedal gait is a developmental throwback. That is, during the normal

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development of a child, following the evolutionary plan in the child’s genes, mayhave been stopped at a point of transition from quadrupedality to bipedality.To be able to progress from a quadrupedal gait, a relatively older walkingstyle, into a newer walking style such as bipedal locomotion, the evolutionarilynewer cerebro-cerebellar control systems regulating asymmetric lateral balancefor upright walking should be developed in children. If not, these childrenwould remain at the older evolutionary stage of a quadrupedal gait, finding itquite easy to walk on all four extremities, as was habitually done by humanancestors. Unfortunately, the location and functioning mechanisms of the newercerebro-cerebellar systems responsible for the dynamics of asymmetric lateralbalance, which is necessary for an upright bipedal gait, are not known.

Cognitive Faculties

Cerebellar and/or vermial damage is indeed to be expected, because thesestructures are involved in balance, locomotion, and cognition in normalindividuals. The mild cerebral cortex atrophy accompanying the cerebellarhypoplasia in individuals with the UTS is associated wit the cerebellarcognitive affective syndrome (Schmahmann & Sherman, 1998), accentuatingthe interconnections between the cerebellum, cerebral association areas, andparalimbic regions. The severe mental impairments observed in individualswith the UTS may be accounted for by the disruption of the cerebro-cerebellarcircuits involved in cognition. Concerning language, these patients seem tounderstand simple questions and commands, although they have difficulties inexpressive language, usually answering questions with an unintelligible sound.This also may be a result of a defect in the cerebro-cerebellar circuits involvedin language, because the cerebellum has reciprocal connections with the leftinferior frontal gyrus and the left lateral temporal cortex (Booth et al., 2007).The role of the cerebellum in speech production has been reported frequently;cerebellar lesions may alter verbal expression and produce slow, monotonousspeech that is not understandable (Fabbro et al., 2000).

Human Evolution

Ancestral Traits. Interestingly, the individuals with the UTS exhibit ancestralfeature, walking on all four extremities coupled with primitive language andrudimentary intelligence. In particular, the affected individuals in the third toseventh families residing near Gaziantep, and those in the last two familiesresiding in the rural areas of Canakkale, had no language skills whatsoever,

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answering simple questions with a simple sound. The affected individuals ofthe first family residing near Iskenderun had more developed language skills;at least, they responded to simple questions with articulated speech, but it wasunderstandable by their mother and father only, and not by their neighbors.

Finding the gene or genes and/or the brain mechanisms responsible forthe UTS may illuminate the mechanisms of the transition from quadrupedalancestors to bipedal ancestors. Studying the fossil records has not beensuccessful in this respect. Indeed, there are live models to study humanevolution, especially with regard to the much discussed transition from habitualquadrupedality to habitual bipedality associated with mental development.Herein, there has been no intent to insult or injure these individuals affected bythe UTS; rather this is an endeavor to better understand the mystery of humanevolution.

Reverse Evolution. The UTS cases are also interesting with respect to reverseevolution, which is manifest in individuals with the UTS as an experiment ofnature. The term “devolution” is preferred instead of reverse evolution, asoriginally used (Tan, 2005b, 2006a). As a result of nature’s experiment, theUTS with ancestral features appeared in these individuals. The UTS casesare the first examples of reverse evolution in humans, which was previouslyinduced in animals during the last several years (Porter & Crandall, 2003;Teotonio & Rose, 2000, 2001; Tvrdik & Capecchi, 2006). According toScienCentralNews (August 31, 2006), Capecchi said on page 1 that “we aretrying to reconstruct what happened during the normal evolutionary process.”Similarly, by studying humans with reverse evolution in the UTS exhibiting themost important ancestral trait, such as the habitual quadrupedal gait, one canunderstand the mechanisms for the transition from habitual quadrupedality tohabitual bipedality, which most likely occurred by punctuated evolution (Elenaet al., 1996) resulting from a genetic mutation, provided that one can determinethe location of the gene or the gene pool responsible for the quadrupedal gaitin the UTS.

Interestingly, reverse evolution is not restricted to genetic mutations; it mayrather be caused by a viral infection in humans, as hitherto described in twocases (Tan, 2007; Munip Arslan herein). In this context, there is evidence thata viral infection may switch the habitual quadrupedal walking pattern into thehabitual bipedal walking pattern, as is also seen in the black macaque monkeyin Israel. These cases also support the theory of punctuated evolution, contraryto Darwin’s theory of graded evolution. If Darwin’s theory of graded evolution

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is correct, all of the monkeys would have started to walk bipedally long ago, atleast imitating man.

To elucidate the genetic or viral mechanisms of the transition fromquadrupedality to bipedality in human beings would be a groundbreakingdevelopment in human history. Therefore, there is no reason to be insultedor suggest injury by the UTS.

Tool Making: Discovery of the Wheel. As a further example for reverseevolution in humans, one of the individuals affected by the UTS, IbrahimYildiz, exhibited an atavistic feature. That is, he fastened a string around hisbelt connected to a wooden box in order to carry it. However, the woodenbox had no wheels; Ibrahim could not think of wheels; he only carried thebox despite the difficulties due to the uneven road. Nobody knew why heliked carrying a box. This is in fact another atavistic feature showing a reverseevolution in an intelligent action, that is, construction of a wheel. His brain wasapparently regressed in this respect and he was not able to invent a wheel tofacilitate carrying objects using a string connected to the box. This is indeedunderstandable, because the invention of the wheel occurred very late in humanevolution. The invention of the wheel is generally considered to have been arevolutionary and world-changing discovery.

The advent of the wheel is relatively recent in the history of humanity.Human ancestors were making many tools for a couple of million years prior tothe wheel. Through the many millennia of the Paleolithic and Neolithic periods,no use of the wheel was known in humans. Before the invention of the wheel,oxen and horses were used as draft animals for vehicles without wheels. Beforethere were wheels, people dragged things across the ground. This is preciselywhat Ibrahim did. That is, he dragged a wooden box without wheels across theground, not realizing the advantages of wheels.

Accordingly, human ancestors constructed various forms of yokes, so thattwo or more persons or animals could work together to drag the same heavyload, without realizing that wheels could in turn carry vehicles. Apparently,one needed a more developed brain to be able to invent wheels to overcomethe difficulty in carrying vehicles; it took millions of years and thereforethe wheel is a relatively recent development in human history. Wheels, oneof the most important inventions of human beings, originated in ancientSumer in Mesopotamia in the fifth millennium BCE, during the early Bronzeage. Interestingly, the emergence of anatomically modern humans occurredapproximately 150,000 years ago, and 143,000 of those years were spent“wheel-less.” So, the man with the UTS dragging a wooden box along the

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roads without using wheels reflects the wheel-less period, suggesting a reverseevolution in intellectual function to more than 150,000 years ago.

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