Humans walking on all fours: return of the ape-man?

By Don Batten, CMI Australia

Reports of a Kurdish family in southern Turkey where several siblings walk on ‘all fours’ instead of upright has caused quite a stir.

Uner Tan of the Cukurova University Medical School in Adana, Turkey, first reported on the family. Five of the 19 offspring walk on all fours,1 although of those five, one daughter and a son occasionally walk briefly on two feet. All five can stand up for a short time, but with both knees flexed and bodies stooped. Those affected are now adults aged from 18 to 34 years in age. The other surviving siblings walk normally.

Some evolutionists, including Uner Tan, have strongly promoted this disability as being an example of an evolutionary throwback to a supposed ape ancestry of humans. He wrote,

‘The new syndrome shows a backward step in the walking pattern, that is, from bipedality in humans to quadrupedality in our closest cousins. In other words, the same specific mutation causing a quadrupedal walk in quadruped patients may also be involved in transition from quadrupedality to bipedality.’1

Tan played the evolution card to the maximum in his paper—it has certainly worked in getting him plenty of publicity.

In like manner, a psychologist at the London School of Economics, Nicholas Humphrey, who has visited the family, said that the people provided ‘an extraordinary window on our past.’2

Other evolutionists disagree about these folk being an evolutionary throwback:

‘Several researchers disputed the idea that the syndrome might represent reversion or backward evolution. The claim is “untestable”, wrote Henrique Teotónio, an evolutionary geneticist at the Gulbenkian Science Institute in Oneiras Portugal, in an email.’3

Humphrey dismissed suggestions that the claims were fraudulent because he said that calluses on the palms of their hands showed that their behaviour was habitual; that is, due to a long-term pattern of behaviour, and so not some temporary exhibition. Humphrey has contributed to a BBC documentary about the family to be aired on March 17, 2006.

People walking on ‘all fours’
Two of the siblings who walk ‘on all fours’, from the BBC documentary. The people suffer from a brain defect that upsets coordination and balance. This has nothing to do with a reversion to an imagined ape ancestry.
Gorilla knuckle-walking
A great ape is designed for knuckle-walking; it is not a defective human. Picture courtesy Wikipedia.org

A genetic defect

Tan wrote that the pattern of inheritance suggests that the condition is due to a recessive mutation on a non-sex chromosome (‘autosomal’) shared by both parents. Such a mutation would result in an expected 25% of the children being affected, which is close to the 5/19 observed (26%), so this suggestion seems reasonable.

A German team have located the mutation to chromosome 17p.4

Brain defect causes the condition

The affected siblings exhibit mental retardation with ataxia (difficulty with balance and coordination)—once again we see mutations causing the disordering and destruction of genetic information, not its creation.

The German team described the condition as ‘hypoplasia of the cerebellum’—that is, the cerebellum (part of the brain) is underdeveloped. Since the cerebellum is responsible for coordination of voluntary muscle movement and balance, it is not surprising that affected people cannot walk normally. This is a rare condition, and affected people can usually walk when given access to mechanical aids from a young age. Clearly, these people from a poor rural area in Turkey did not have access to appropriate help at a young age and had to resort to getting around on all fours because they could not coordinate and balance well enough to walk upright.

If this were a reversion to our ape ancestry, then apes such as chimpanzees should have underdeveloped cerebellums. This is not the case; otherwise they would not be as incredibly agile as they are. No, the cerebellums of the apes are well developed and they do not exhibit ataxia (inability to coordinate muscles or to balance). Indeed, apes such as bonobos can balance quite well enough for walking upright, but their leg, spine, pelvis and neck anatomy is just not suited to doing so habitually. Also, the people ‘walk’ on the palms of their hands; they are not knuckle-walking, as the great apes do (and as ‘Lucy’ apparently did).

The gait of the Turkish siblings is quite ungainly, partly due to the inappropriate lengths of legs versus arms for quadrupedal walking. However, apes knuckle-walk quite naturally, due to the much greater arm-to-leg length ratio compared to humans, combined with the locking mechanism in their wrists. Furthermore, because humans have the ‘wrong’ pelvic, knee and foot anatomy, these people had to ‘walk’ with straight legs, giving a very ungainly movement. In short, apes were designed to knuckle-walk; it is not a defect that evolution rectified to make humans. Our Creator designed us humans for upright walking (see Standing upright for creation for how our spines were meant for walking)


This is yet another fanciful attempt by some evolutionists to make evolutionary propaganda out of what is merely a genetic defect in some unfortunate people. And yet again the BBC is complicit in spreading the propaganda. To suggest that people suffering from an inherited genetic defect are throwbacks, or otherwise less than fully human, is a cruel denial of the Bible’s clear teaching that we are all descendants of Adam and Eve, created in the image of God, but marred by sin.

Addendum: consequences of inbreeding?

The mother and father are closely related, apparently sharing a recessive gene for the condition, such that 25% of their children are affected. Close marriages are common in the Middle East and defects in the children of such marriages are also common. As we have pointed out, the accumulation of deleterious mutations following the Fall (Genesis 3), could have been a significant factor in God outlawing close (e.g., brother–sister) marriage at the time of Moses (~1500 BC), whereas in the early generations it would have not been a problem (e.g. for Cain and his sister).


  1. Tan, U., A new syndrome with quadrupedal gait, primitive speech, and severe mental retardation as a live model for human evolution. International Journal of Neuroscience 116(3):361–369, March 2006. Return.
  2. Agence France Presse (AFP) News report. Yahoo! Inc, March 7, 7:56 am, 2006.Return.
  3. Claim of reversed human evolution provokes skepticism, interest. 27 Feb. 2006, Special to World Science http://www.world-science.net/exclusives/060225_syndromefrm.htm Return.
  4. Turkmen, S., et al., Cerebellar hypolasia and quadrupedal locomotion in humans as a recessive trait mapping to chromosome 17p. J. Medical Genetics, Dec 21 2005 (epublication ahead of print). doi:10.1136/jmg.2005.040030 Return.