The Ulas family of Turkey, five of whom walk on all fours, became known to the world after being featured in a 2006 BBC documentary.

The Ulas family of Turkey, five of whom walk on all fours, became known to the world after being featured in a 2006 BBC documentary.

Early research suggested that their condition was an example of reverse evolution, but now a recent study says that’s not the case.

The original diagnosis was made by Turkish biologist Uner Tan. The anomaly was named Uner Tan syndrome.

He said that the siblings’ cognitive and balance impairments along with the unique walking style was evidence of a new syndrome that suggested devolution was occurring.

Based on that theory, gradual evolutionary human changes like walking upright could quickly begin to vanish at any time.

Many scientists scoffed at the idea, pointing out that the Ulas siblings didn’t actually walk like apes, even though they placed both their hands and feet on the ground.

The most recent alternative theory expands upon those observations and concludes that the siblings are affected by cerebellar hypoplasia.

It also affects balance,but the fact that the adult siblings walk on all fours is evidence of adaptation rather than a backwards move on the evolutionary timeline.

The researcher responsible for the re-diagnosis said she simply wanted to set the record straight.