Üner Tan Syndrome: Review and Emergence of Human Quadrupedalism in Self-Organization,\ud Attractors and Evolutionary Perspectives\ud

The first man reported in the world literature exhibiting habitual quadrupedal locomotion was discovered by a British traveler and writer on the famous Baghdat road near Havsa/Samsun on the middle Black-Sea coast of Turkey (Childs, 1917). Interestingly, no single case with human quadrupedalism was reported in the scientific literature after Child's first description in 1917 until the first report on the Uner Tan syndrome (UTS: quadrupedalism, mental retardation, and impaired speech or no speech)in 2005 (Tan, 2005, 2006). Between 2005 and 2010, 10 families exhibiting the syndrome were discovered in Turkey with 33 cases: 14 women (42.4%) and 19 men (57.6%). Including a few cases from other countries, there were 25 men (64.1%)and 14 women (35.9%). The number of men significantly exceeded the number of women (p < .05). Genetics alone did not seem to be informative for the origins of many syndromes, including the Uner Tan syndrome. From the viewpoint of dynamical systems theory, there may not be a single factor including the neural and/or genetic codes that predetermines the emergence of the human quadrupedalism.Rather, it may involve a self-organization process, consisting of many decentralized and local interactions among neuronal, genetic, and environmental subsystems. The most remarkable characteristic of the UTS, the diagonal-sequence quadrupedalism is well developed in primates. The evolutionarily advantage of this gait is not known. However, there seems to be an evolutionarily advantage of this type of locomotion for primate evolution, with regard to the emergence of complex neural circuits with related highly complex structures. Namely, only primates with diagonal-sequence quadrupedal locomotion followed an evolution favoring larger brains, highly developed cognitive abilities with hand skills, and language, with erect posture and bipedal locomotion, creating the unity of human being. It was suggested that UTS may be considered a further example for Darwinian diseases, which may be associated with an evolutionary understanding of the disorders using evolutionary principles, such as the natural selection. On the other hand, the human quadrupedalism was proposed to be a phenotypic example of evolution of reverse, i.e., the reacquisition by derived populations of the same character states as those of ancestor populations. It was also suggested that the emergence of the human quadrupedalism may be related to self-organizing processes occurring in complex systems, which select or attract one preferred behavioral state or locomotor trait out of many possible attractor states. Concerning the locomotor patterns, the dynamical systems in brain and body of the developing child may prefer some kind of locomotion, according to interactions of the internal components and the environmental conditions, without a direct role of any causative factor(s), such as genetic or neural codes, consistent with the concept of self-organization, suggesting no single element may have a causal priority

UNERTAN SYNDROME: A CASE SERIES DEMONSTRATING HUMAN DEVOLUTION

A large family with six individuals exhibiting the Unertan syndrome (UTS)was identified residing in southern Turkey. All of the individuals had mental impairments and walked on all four extremities. The practice of intra-familial\ud marriages suggested that theUTS may be an autosomal recessive disorder, similar to previously described cases. The inferior portions of the cerebellum and vermis were\ud absent as evidenced by MRI and CT scans. The height and head circumference of those affected were within normal ranges. Barany’s test suggested normal vestibular\ud system function. The subjects could not name objects or their close relatives. The males (n = 4) could understand simple questions and commands, but answered questions with only one or two sounds. The females (n = 2) were superior to\ud the males with respect to language skills and walking, suggesting an association between walking and speaking abilities. One male exhibited three walking patterns\ud at the same time: quadripedal, tiptoe, and scissor walking. Another male used two walking styles: quadripedal and toe-walking. It is emphasized that there are important differences between the UTS and the disequilibrium syndrome. It is suggested that the inability to walk upright in those affected with the UTS may be\ud best explained by a disturbance in lateral-balance mechanisms,without being related to the cerebello-vestibular system.An interruption of locomotor development during the transition from quadripedality to bipedality may result in habitual walking on all four extremities and is normal in some children. Because quadripedal\ud gait is an ancestral trait, individuals with the UTS, exhibiting a manifestation of reverse evolution in humans, may be considered an experiment of nature, useful\ud in understanding the mechanisms underlying the transition from quadripedality to bipedality during human evolution. The proposed mutant gene or gene pool playing\ud a role in human quadrupedality may also be responsible for human bipedality at the same time. Herein there is no intent to insult or injure; rather, this report is an\ud endeavor to better understand human beings. Supplementary materials are available for this article. Go to the publisher’s online edition of International Journal of\ud Neuroscience for the following free supplemental resource(s): video clips

UNERTAN SYNDROME: A CASE SERIES DEMONSTRTAING HUMAN DEVOLUTION

A large family with six individuals exhibiting the Unertan syndrome (UTS) was identified residing in southern Turkey. All of the individuals had mental impairments and walked on all four extremities. The intra-familial marriages suggested that the UTS is an autosomal recessive disorder. The inferior portions of the cerebellum and vermis were absent as evidenced by MRI and CT scans. The height and head circumference of those affected were within normal ranges. Barany’s test suggested normal vestibular system function. The subjects could not name objects or their close relatives. The males (n = 4) could understand simple questions, answering them with only one or two sounds. The females (n = 2) were superior to the males with respect to language skills and walking, suggesting an association between walking and speaking abilities. One male exhibited three walking patterns at the same time: quadripedal, tiptoe, and scissor walking. Another male used two walking styles: quadripedal and toe-walking. It is emphasized that there are important differences between the UTS and the disequilibrium syndrome (DES). It is suggested that the inability to walk upright in those affected with the UTS may be best explained by a disturbance in lateral-balance mechanisms. An interruption of locomotor development during the transition from quadripedality to bipedality may result in habitual walking on all four extremities and is normal in some children. Since quadripedal gait is an ancestral trait, individuals with the UTS, exhibiting a manifestation of reverse evolution in humans, may be considered an experiment of nature, useful in understanding the mechanisms underlying the transition from quadripedality to bipedality during human evolution. The proposed mutant gene or gene pool playing a role in human quadrupedality may also be responsible for human bipedality at the same time. Herein there is no intent to insult or injure, rather this report is an endeavor to better understand human beings