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Professor Humphrey, who has been contributing to a BBC programme, The Family that Walks on All Fours, to be broadcast on March 17, said that weeks of study, and factors such as their hands’ shape and callouses, showed that this was a long-term pattern of behaviour and not a hoax. “However they arrived at this point, we have adult human beings walking like ancestors several million years ago,” he said.
The siblings, who live with their parents and 13 other brothers and sisters, are mentally retarded, as a result of a form of cerebellar ataxia — an underdevelopment of the brain similar to that in cystic fibrosis. Their mother and father, who are themselves closely related, are believed to have passed down a unique combination of genes resulting in the behaviour. While Professor Humphrey said that cultural influences in their upbringing may have played a crucial role, with parental tolerance allowing the children to keep to quadrupedal walking, others believe that the cause is more purely genetic.
Uner Tan, a professor of physiology at Cukurova University in Adana, Turkey, who first brought the family to the attention of scientists, argues that the gene mutations have made them regress to a “missing link” primate state, also explaining their severe problems with language. A team of German geneticists believes that the family holds the key to a breakthrough gene for bipedality.
Researchers said that while the women affected, Safiye, 34, Senem, 22, and Amosh, 18, tended to spend their time sitting outside the family’s basic rural home, one brother, Huseyin, 28, went into the local village on all fours, where he could engage in basic interactions. http://www.timesonline.co.uk/article/0,,3-2072832,00.html
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