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These individuals may have reverted to an ancient mode of locomotion. (Photo: BBC) |
Five siblings from Turkey who move by crawling on all fours may provide science with new insights into human evolution.
Among them are four sisters and one brother, aged between 18 and 34. Professor Nicholas Humphrey from the London School of Economics believes they could offer evidence that our ancestors transitioned from walking on all fours to walking on two legs. However, he also dismisses the notion of a specific “gene” for bipedalism or upright walking.
Three of the daughters and one son can only move on all fours, while the fourth daughter, in addition to this unusual method, can also walk in a normal bipedal manner. Another brother only walks on two legs, but with great difficulty.
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Calluses on their hands indicate that they are not faking. (Photo: BBC) |
All five live with their parents and five other siblings. They were born with brain damage. MRI scans indicate they may suffer from a form of cerebellar ataxia—a condition that affects balance and coordination of limbs.
However, scientists have yet to agree on the cause of these individuals walking on all fours.
Professor Humphrey believes the locomotion method of these Turkish individuals is entirely different from that of our closest relatives, chimpanzees and gorillas. While gorillas and chimpanzees walk on their knuckles, these five siblings put their weight on their wrists and lift their fingers off the ground.
“These individuals keep their fingers very agile; for instance, the girls in the family can still sew and knit“, whereas chimpanzees severely damage their fingers with their mode of locomotion.
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The five individuals with this unusual gait grew up in a remote area of Turkey. (Photo: BBC) |
Humphrey also added that the calluses on one family member’s hands prove that their behavior is not fabricated. He suggests this could be a remnant of the walking style of our early ancestors.
Humphrey believes that the brain abnormalities simply allow these five siblings to revert to the locomotion style of our ancestors. “Due to their unique circumstances, they maintain a walking style similar to that of an infant“, he stated.
However, a research group led by Stefan Mundlos from the Max Planck Institute in Berlin, Germany, argues that the genetic abnormality causing this unusual movement may play a more fundamental role in evolution. Professor Mundlos has pinpointed a gene on chromosome 17 and hypothesizes that an important gene in the transition to bipedalism may have been lost in these individuals.
A documentary about their family will air on BBC on March 17.
T. An
