The Ulas family of 19 is from rural southern

Turkey Turkey, officially the Republic of Türkiye, is a country mainly located in Anatolia in West Asia, with a relatively small part called East Thrace in Southeast Europe. It borders the Black Sea to the north; Georgia (country), Georgia, Armen ...

. Five of the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

members (except for another, who has died) walk on all fours with their feet and the palms of their

hand A hand is a prehensile, multi-fingered appendage located at the end of the forearm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs. A few other vertebrates such as the Koala#Characteristics, koala (which has two thumb#O ...

s in what is called a "bear crawl". Their quadrupedal

gait Gait is the pattern of Motion (physics), movement of the limb (anatomy), limbs of animals, including Gait (human), humans, during Animal locomotion, locomotion over a solid substrate. Most animals use a variety of gaits, selecting gait based on s ...

had never been reported in anatomically intact

adult An adult is an animal that has reached full growth. The biological definition of the word means an animal reaching sexual maturity and thus capable of reproduction. In the human context, the term ''adult'' has meanings associated with social an ...

humans, but was later also discovered in other families in the region. The gait is different from the knuckle-walking quadrupedal gait of apes. In 2006, the family was the subject of a

documentary A documentary film (often described simply as a documentary) is a nonfiction Film, motion picture intended to "document reality, primarily for instruction, education or maintaining a Recorded history, historical record". The American author and ...

: '' The Family That Walks on All Fours''. The affected people have a form of non-progressive congenital cerebellar ataxia. The brain impairments include

cerebellar hypoplasia Cerebellar hypoplasia is characterized by reduced cerebellar volume, even though cerebellar shape is (near) normal. It consists of a heterogeneous group of disorders of cerebellum, cerebellar maldevelopment presenting as early-onset Non-progress ...

, mild

cerebral cortex The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. It is the largest site of Neuron, neural integration in the central nervous system, and plays ...

atrophy Atrophy is the partial or complete wasting away of a part of the body. Causes of atrophy include mutations (which can destroy the gene to build up the organ), malnutrition, poor nourishment, poor circulatory system, circulation, loss of hormone, ...

and a reduced

corpus callosum The corpus callosum (Latin for "tough body"), also callosal commissure, is a wide, thick nerve tract, consisting of a flat bundle of commissural fibers, beneath the cerebral cortex in the brain. The corpus callosum is only found in placental ...

. They are also mildly

intellectually disabled Intellectual disability (ID), also known as general learning disability (in the United Kingdom), and formerly mental retardation (in the United States), Rosa's Law, Pub. L. 111-256124 Stat. 2643(2010).Archive is a generalized neurodevelopmental ...

and have problems in balancing on two legs. However, they do not show the poor coordination of

speech Speech is the use of the human voice as a medium for language. Spoken language combines vowel and consonant sounds to form units of meaning like words, which belong to a language's lexicon. There are many different intentional speech acts, suc ...

, and

eye An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system. In higher organisms, the ey ...

movements often found in cerebellar ataxia. The four sisters can do

needlework Needlework refers to decorative sewing and other textile arts, textile handicrafts that involve the use of a Sewing needle, needle. Needlework may also include related textile crafts like crochet (which uses a crochet hook, hook), or tatting, ( ...

. They all share a

recessive In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and ...

mutation In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, ...

chromosome 17 Chromosome 17 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 17 spans more than 84 million base pairs (the building material of DNA) and represents between 2.5 and 3% of the total DN ...

Sources

Üner Tan of Çukurova University Medical School in

Adana Adana is a large city in southern Turkey. The city is situated on the Seyhan River, inland from the northeastern shores of the Mediterranean Sea. It is the administrative seat of the Adana Province, Adana province, and has a population of 1 81 ...

, said that they show characteristics of the

primate Primates is an order (biology), order of mammals, which is further divided into the Strepsirrhini, strepsirrhines, which include lemurs, galagos, and Lorisidae, lorisids; and the Haplorhini, haplorhines, which include Tarsiiformes, tarsiers a ...

ancestors of ''

Homo sapiens Humans (''Homo sapiens'') or modern humans are the most common and widespread species of primate, and the last surviving species of the genus ''Homo''. They are Hominidae, great apes characterized by their Prehistory of nakedness and clothing ...

'', before the move to

bipedalism Bipedalism is a form of terrestrial locomotion where an animal moves by means of its two rear (or lower) Limb (anatomy), limbs or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning 'two feet' (from ...

. He called the process "backward evolution" and he named the condition Uner Tan syndrome. However,

Nicholas Humphrey Nicholas Keynes Humphrey (born 27 March 1943) is an English neuropsychologist based in Cambridge, known for his work on the evolution of primate intelligence and consciousness. He studied mountain gorillas with Dian Fossey in Rwanda; he was t ...

, John Skoyles, and Roger Keynes have argued that their gait is due to two rare phenomena coming together. First, instead of initially crawling as infants on their knees, they started off

learning Learning is the process of acquiring new understanding, knowledge, behaviors, skills, value (personal and cultural), values, Attitude (psychology), attitudes, and preferences. The ability to learn is possessed by humans, non-human animals, and ...

to move around with a "bear crawl" on their feet. Second, due to their

congenital A birth defect is an abnormal condition that is present at childbirth, birth, regardless of its cause. Birth defects may result in disability, disabilities that may be physical disability, physical, intellectual disability, intellectual, or dev ...

brain impairment, they found balancing on two legs difficult. Because of this, their motor development was channeled into turning their bear crawl into a substitute for bipedality. Defne Aruoba is a Turkish psychologist who was involved with the care and research of the Ulas family. Because of her experience working with the Ulas family, she planned to establish the Ulas Foundation, which will bridge the gap between social inequalities and contact other individuals and families in need of rehabilitation.

References

{{reflist Congenital disorders Kurdish families Turkish families

Sources

See also

References