The Family That Walks on All Fours

Lore & Background

In January 2006, the filmmakers returned to find that parallel bars had been placed outside on Dr. Ali's advice for upright walking exercise, which the family used nearly every day. The film closes with Hüseyin walking up a path on two legs, showing progress. Nicholas Humphrey concluded the condition was due to a rare set of genetic and developmental circumstances, likely unrelated to genes involved in human evolution of upright walk.

Reader's Guide

The significance of the Ulas family lies in the scientific debate their gait sparked, including controversial speculation known as Uner Tan syndrome, which proposed it might be a genetic throwback to pre-bipedal hominid locomotion. However, Nicholas Humphrey's conclusion—that the quadruped gait results from a combination of an inherited recessive mutation causing cerebellar ataxia and the developmental circumstance of perfecting an initial bear-crawl—shifted the focus away from evolutionary throwback theories. The documentary brought global attention to the family, highlighting the interplay of genetics, development, and environment in human locomotion. Its legacy includes raising questions about the nature of bipedalism and the limits of human adaptation, while also emphasizing the family's humanity and resilience. The revised NOVA version broadened scientific perspectives, ensuring the story reached a wider audience. The family's case remains a unique example of how rare genetic conditions can illuminate normal developmental processes.

Did You Know?

• The documentary was broadcast on BBC Two on 17 March 2006 and a revised version on NOVA on 14 November 2006.
• The affected siblings walk using a bear-crawl, on their feet rather than their knees.
• Their mother, Hatice, saw the sea for the first time during the documentary and said she did not know Allah had made such beauty.
• Nicholas Humphrey concluded the gait was due to a rare set of genetic and developmental circumstances, not genes involved in human evolution of upright walk.

The Scientific Puzzle

The documentary centers on a previously unreported quadruped gait displayed by five members of the Ulas family, who live in Southeastern Turkey. The scientific community has long debated what causes this unusual mode of locomotion. Turkish researcher Uner Tan proposed what he called the Uner Tan syndrome, a controversial theory suggesting the family represents a genetic throwback to pre-bipedal hominid movement. However, Nicholas Humphrey, a British scientist who accompanied the film crew, offered a different explanation. He concluded that the walking pattern resulted from a rare convergence of genetic and developmental factors. The family's mother recalled that all nineteen of her children initially moved using a bear-crawl on their feet rather than their knees. A recessive inherited mutation gave the affected siblings a non-progressive congenital cerebellar ataxia, which disrupted the balance normally required to transition to upright walking. Unable to master bipedal locomotion, these children refined their early crawl into a fully developed adult quadruped gait. Crucially, Humphrey stressed that this condition almost certainly has no connection to the genes that drove the evolution of upright walking in humans.

A Family in the Spotlight

The Ulas household in Southeastern Turkey is a large one, with nineteen children born to father Resit and mother Hatice. Of those nineteen, twelve developed typically while seven faced physical challenges, and one child tragically passed away. The five individuals who walk on all fours include four sisters—Safiye, Hacer, Senem, and Emine—along with their brother Hüseyin. A sixth affected child, Gülin, staggers as though intoxicated yet manages to walk on two legs. The documentary captures a deeply moving moment when the family, despite living only an hour's drive from the coast, travels to a sandy beach for the very first time. They paddle in the waves and touch the water with wonder. Hatice, seeing the sea for the first time in her life, remarks that she had no idea Allah had created such beauty. When told the film would place the world's attention on them, Resit expresses his wish that they not be likened to monkeys. Though he does not accept evolution, he philosophically notes that words cannot truly harm them and that the film might bring some help and a measure of understanding.

Production and Broadcast

The documentary was produced by Passionate Productions and first aired on BBC Two on 17 March 2006. Jemima Harrison served as writer, director, narrator, and editor, while Jon Lane handled photography and producing duties. The project originated in June 2005 when Nicholas Humphrey received a phone call from John Skoyles, who had come across an unpublished paper by Uner Tan examining hand dominance in the family. This led to a visit by two British scientists alongside Tan to meet the Ulas family and their father Resit. The production team included additional contributors such as computer modeler Premog, titles designer Alex Pritchard, and additional photographer Darren Hercher. BBC executive producer Richard Klein oversaw the project, while consultants Defne Aruoba and Cetin Mursalioğlu assisted in Turkey and Roger Keynes and John Skoyles provided UK-based consultation. A revised cut of the film, which reframed the narrative away from the discovery story and incorporated perspectives from additional scientists, was later broadcast on the American channel NOVA on 14 November 2006.

Hope and a Final Walk

When the film crew returned to the Ulas family in January 2006, a significant change had taken place. Following advice from Dr. Ali, parallel bars had been installed outside the home so the affected siblings could practice upright walking. The family had been using them nearly every day, and the documentary captures them smiling as they made visible progress in learning to walk on two legs. The film's closing image is particularly poignant: Hüseyin, one of the five quadruped walkers, is shown walking up a path on his two legs. This moment of triumph stands in contrast to the earlier scenes of struggle and the sadness that permeates the family's daily life. Yet the documentary also carries an undercurrent of urgency. Nicholas Humphrey voiced his concern that this particular phenomenon—this rare convergence of genetic and developmental factors producing a quadruped gait in humans—might never be observed again. The family's story, preserved on film, may represent a uniquely fleeting glimpse into a form of human locomotion that exists nowhere else in the world.