Uner Tan syndrome Üner Tan

according tan, persons affected syndrome walk quadrupedal locomotion , afflicted primitive speech , severe mental retardation; postulated example of backward evolution. proposed syndrome after studying ulas family of rural southern turkey, 5 of whom have these symptoms. proposed syndrome featured in 2006 bbc2 documentary family walks on fours. after study of ulas family, tan went on diagnose uner tan syndrome in several other families.

neuroscientist , evolutionary psychologist roger keynes, psychologist nicholas humphrey , medical scientist john skoyles have argued gait of these individuals due 2 rare phenomena coming together, not atavism. first, instead of crawling infants on knees, started off learning move around bear crawl on feet. second, due congenital brain impairment, found balancing on 2 legs difficult. because of this, motor development channeled turning bear crawl substitute bipedalism.

in bbc documentary family walks on fours, nicholas humphrey refers uner tan s devolutionary description of ulas family scientifically irresponsible.