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The Five Siblings of the Ulas Family Who Walk on All Fours

Discovered in 2005 at a remote, undisclosed, location in southern Turkey, the Ulas family were the subject of a BBC documentary called The Family That Walks on All Fours. The family became the center of debate among scientists who favored different theories to explain their condition. Though at first it was speculated that the five siblings might be a genetic throwback to the quadrupedal locomotion of hominids, it came to light that they have a brain defect that makes it difficult for them to stand upright. Here is more about the five siblings, their family, and what the world of science had to say about it.

The Ulas family is a Kurdish family of 19 children and their parents, five of whom exhibit a quadrupedal gait, walking on all fours, something that has never been reported before in anatomically intact humans. 

The Family That Walks on All Fours
Image Source: BBC

Among the 19 children of Resit and Hatice, the father and mother, 12 are normal and the other seven have problems with their gait. One of the seven children died and one, Gülin, can walk upright but “looks drunk” suggesting problems with balance. Of the rest of the five siblings are four sisters, Safiye, Hacer, Senem, and Emine, and a brother Hüseyin. These siblings walk on all fours with their feet rather than knees and the wrist side of the palm. Such gait is known as “bear crawl.”


Among the theories put forward to explain this walk was the theory of “backward evolution,” a missing gene, and that it’s a combination of cerebellar ataxia and how they were raised. 

Brain Scans of the Ulas Family Siblings
Image Source: BBC

According to Uner Tan, an evolutionary biologist at Çukurova University Medical School in Adana, Turkey, the siblings show characteristics of our primate ancestors before they learned to walk upright. He believes it to be “backward evolution” and calls it “Uner Tan Syndrome.” According to Professor Stefan Mundlos, a Berlin-based geneticist, a specific gene is responsible for bipedalism which he believes must be missing in the siblings.

Nicholas Humphrey, an English psychologist, heard of Tan’s unpublished paper from neuroscientist and evolutionary psychologist John Skoyles and believes it to be cerebellar ataxia. The cerebellum is responsible for balance and spatial orientation; damage to it often results in disturbances in balance and gait.

According to Roger Keynes, a British medical scientist, they have a defect in their cerebellar vermis. However, damage to cerebellum did not explain how Gülin, who inherited the same defect, could walk bipedally, though with a little difficulty. So, Humphrey, Skoyles, and Keynes argue that the problem is twofold—a rare combination of an inherited, recessive, genetic mutation that caused non-progressive congenital cerebellar ataxia and their upbringing.


Though they have problems balancing on two legs, there are no signs of poor coordination of hands, speech, or eye movement. The sisters also enjoy crocheting and embroidery. 

Ulas Siblings
Image Source: BBC

Since the siblings do not use their entire hand when walking, their fingers are saved from any damage. This is unlike chimpanzees and gorillas which use the knuckles of their hands while walking. According to Humphrey, Resit told him that he did not regard his children as handicapped and so did not seek to correct their gait.

The parents explained that when the children were infants, their crawl was normal, that is on hands and knees. But, it gradually changed to the bear crawl. Humphrey believes that, since they would have found it difficult to stand upright, they probably simply kept using their hands as well to “make the best of a bad job.”

Following the filming of the documentary, efforts were made to introduce physiotherapy to the family and to establish an Ulas Foundation to help them and anyone else in need of rehabilitation. 

Practicing Walking with a Parallel Bar
Image Source: BBC

Though Resit and Hatice are supportive of their children, they face hostility from their local village, and children taunt Hüseyin. They had to move to a different house because people thought their previous home was cursed, and no one would help when they ran out of water.

Turkish psychologist Defne Aruoba, who was involved in the care and research of the family and served as their translator, is planning on establishing an Ulas Foundation to bridge the gaps between social inequalities and to help others. The crew gave the family parallel bars so that they could exercise and practice walking upright.

Here’s the documentary The Family That Walks on All Fours uploaded by Nicholas Humphrey. 

[sources: wikipedia, nationalgeographic, washingtonpost]

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