'Family That Walks on All Fours' Not Evolutionary Throwbacks

By Stephanie Pappas

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A person with Uner Tan Syndrome walks on all fours. Credit: Shapiro LJ, Cole WG, Young JW, Raichlen DA, Robinson SR, et al. (2014) Human Quadrupeds, Primate Quadrupedalism, and Uner Tan Syndrome. PLoS ONE 9(7): e101758. doi:10.1371/journal.pone.0101758 View full size image

When Turkish evolutionary biologist Uner Tan introduced the world to a Turkish family with some members who could walk only on all fours, in a "bear crawl," he and other scientists speculated this odd gait was the resurgence of a trait lost during human evolution.
Not so, a new study finds.
The family and other people with Uner Tan syndrome do not represent "a backward stage inhuman evolution," as Tan wrote in a 2006 paper in the International Journal of Neuroscience, said Liza Shapiro, a professor of anthropology at the University of Texas at Austin. In new research, Shapiro and her colleagues compared videos of the family's gait with the gaits of nonhuman primates, such as chimpanzees or gorillas. They found the gait patterns did not match. Instead ofrecreating ape walks, people with Uner Tan are simply adapting to their disorder, Shapiro and her colleagues reported July 16 in the journalPLOS ONE.