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Family That Walks on All Fours

PBS Airdate: November 14, 2006
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NARRATOR: In a remote corner of Turkey, five unusual siblings come to the attention of the world. Victims of a mysterious condition, pariahs in their village, they now face international scrutiny, and all because of how they walk—on their feet and their hands.

What could possibly have caused this?

The family sparks a fierce debate among scientists around the world. Some create a sensation in the popular press, claiming the handwalkers represent a backward stage in evolution. Others believe their disability may hold clues to how we came to walk upright.

STEFAN MUNDLOS (Charité Universitätsmedizin Berlin): Within the DNA of this family, there is going to be that gene that we still have to find, which may be involved in the evolution of this very human trait.

NARRATOR: Some argue the handwalkers have been shaped less by genes than by the world around them.

NICHOLAS HUMPHREY (London School of Economics): Those kind of behavioral changes don't occur as a result of one or two genes changing. I'm quite certain that there's something in the background of this astonishing family that changed the behavior of the children in this family, so that they had failed to get up on two legs.

NARRATOR: But whether the handwalkers tell us anything about the past, their personal story is about to change forever.

The Family That Walks On All Fours, up next on NOVA.

Google is proud to support NOVA in the search for knowledge: Google.

Major funding for NOVA is provided by the Howard Hughes Medical Institute, serving society through biomedical research and science education: HHMI.

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NARRATOR: In this remote region of simple villages, Professor Uner Tan is about to reveal a momentous discovery. He and his colleagues from a leading Turkish university have already made this journey, but never with outsiders, until now. Among the carefully chosen guests is Nicholas Humphrey, well known for his research into the origins of consciousness. It was not an invitation Humphrey could lightly refuse, for, according to Tan, they are about to meet people in whom evolution has gone into reverse.

NICHOLAS HUMPHREY: This is a very exciting moment for us. We are just entering this village in Southern Turkey, near the border of Syria, where we've heard of this remarkable family which, we're told, have got several children who walk on all fours, on their hands as well as their feet. And since they were children, they have never stood upright. We don't quite know what we are going to expect from... whether we'll really see quadrupedal humans. I don't know. It's never been reported in the scientific literature. Gunaydin and Resit

NARRATOR: Resit Ulas has fathered 19 children, a lot even by local standards in this rural Kurdish village. Twelve of them were born totally healthy, but six weren't, five of whom survive.

The first glimpse of their condition soon appears from down the road. This is Gulin. At first sight, he looks drunk, but he isn't. There's something wrong with his balance. Still, he's on two feet, not four.

But then, one by one, the others appear. There are four afflicted daughters and one son.

Huseyin has walked like this for 28 years. In this simple village such a dramatic abnormality can elicit fear and hostility. The local children taunt Huseyin in particular.

A few years ago, the family was told their house was cursed, so they rebuilt it further up the hill. Last year, when they ran out of water, no one would help.

NICHOLAS HUMPHREY: My heart goes out to them. It's an amazing thing to see these people. They're so familiar; they're human like ourselves, and yet in many ways they're walking in a way in which no humans, no adult humans, have walked for 3,000,000 years. What's behind it? We don't know.

We're going to have to tease away, pick away at this, to find out what underlies this extraordinary phenomenon.

NARRATOR: The next day, Turkish psychologist Defne Aruoba joins Nick Humphrey and Uner Tan to help interview the family.

DEFNE ARUOBA: Okay, this is Senem.

NICHOLAS HUMPHREY: And how old is she?

DEFNE ARUOBA: Twenty four.

NICHOLAS HUMPHREY: Okay. And this is?

NARRATOR: The affected siblings are between 18 and 34 years old. They all still live at home, cared for by their siblings and by their parents.

DEFNE ARUOBA: Her short name is Emos.

NICHOLAS HUMPHREY: Emos. And do we know how old Emos is?

DEFNE ARUOBA: I think she is just a little younger than Senem, so she must be, like, early twenties.

NICHOLAS HUMPHREY: And this is Huseyin. And this is Safiye?



NARRATOR: The scientists soon discover that the parents are cousins.

DEFNE ARUOBA: He is her mother's mother's brother's son.

NARRATOR: This marriage between close relatives increases the risk that the children have inherited a faulty gene. Tan believes this is the gene that lets us walk upright. He suspects a harmful mutation has shut it down, returning the siblings to a primitive state when our ancestors walked on all fours.

His claim has met with skepticism, but if he's right, this unusual family would offer us a living glimpse into our past.

UNER TAN (Çukurova University): We see, in this family with primitive characteristics, like quadrupedal walking, possibly, a good example of how our ancestors lived millions of years ago. And this living example may ultimately be more, even, important than studying fossils.

NICHOLAS HUMPHREY: What was so obvious here was that this could be a candidate for an ancestral human form of locomotion. Here was, potentially, a window onto something which lots of us have imagined: what was it like to walk on four legs before we became bipedal? What changed to make us bipedal? This was, obviously, terribly exciting.

NARRATOR: Standing upright is one of the key human characteristics. It sets us apart from all other primates.

Occasionally, animals are born without forelimbs, and they find ways to compensate. This is Faith, the dog who brings traffic to a standstill in Oklahoma City.

Our closest relative, the chimpanzee, is also an occasional biped. And other animals dabble in bipedality too, sometimes rather spectacularly.

But no one does it quite like we do. And that's because we have developed a breathtaking sense of balance. Humans are exquisitely adapted for life on two feet. But when did we get this way? And how?

No one knows when our ancestors stood up, but there are clues. The most haunting is this trail of human-looking footsteps unearthed in Tanzania. Whoever made them walked on two feet over 3,000,000 years ago. Scientists think they were left by an ancestor of ours called Australopithecus.

The most famous fossil is Lucy, a skeleton found in Ethiopia, in 1974. For decades, researchers pored over her bones, leaving no doubt they belonged to a biped. Then two young scientists noticed something new that said very little about Lucy, but a lot about her ancestors.

BRIAN RICHMOND (The George Washington University): We see, in her skeleton, evidence of a wrist structure that's shared with chimpanzees and gorillas, that's related to their very unusual way of walking, which is walking on their knuckles.

NARRATOR: To protect their long fingers, chimps and apes curl them up and walk on the backs of them. Unlike humans, who can bend their wrists 90 degrees, the wrist of apes and chimps is stiff, to provide support for knuckle-walking.

BRIAN RICHMOND: Now, if we focus on the wrist joint itself, we can see that the human wrist is very flat, and that's what allows all that mobility in the wrist. The chimpanzee wrist is not flat. It has a bar of bone sticking out into the wrist joint that provides that stability. Now, if we look at a four-million-year-old human ancestor's wrist, we can see that it also has that bar of bone that sticks out into the wrist. And this indicates that this early biped evolved from an ancestor that was climbing in the trees and knuckle-walking on the ground.

NARRATOR: So if the handwalkers reveal the gait of our ancestors, they should be walking on their knuckles, not their palms.

BRIAN RICHMOND: These handwalkers have a modern human skeleton. And that's really what allows them to walk on the palms of their hands. The modern human wrist allows the hand to rotate back almost 90 degrees. We have a very mobile wrist joint, because it's very flat. And it's unlikely that our ancestors could have even walked on their palms, because their wrist structure wouldn't have allowed it.

Now, that fossil evidence is much stronger than any kind of evidence we would find from a living, unusual case, like this case of the people walking on all fours.

NARRATOR: But even if the handwalkers lack the physical architecture of our ape-like ancestors, could ancient genes be prompting them to mimic ancestral behaviors as best they can?

Professor Tan, a neuroscientist, believes they are. He and his wife, Meliha, a neurologist, examine the children. Basic neurological tests confirm there is something wrong with their brains.

Next, Tan checks their ability to do simple tasks. Huseyin manages to do this hand skills test fairly well, but Safiye struggles to understand what she's being asked to do.

The handwalkers, Tan concludes, have limited intelligence, language and fine motor skills, characteristics he associates with our pre-human ancestors. A defect in the siblings' genes has produced something he calls "reverse evolution."

UNER TAN: By reverse evolution, I mean that some defects in some genes may cause very ancient characteristics to be expressed. But reverse evolution has nothing to do with time; it's a term that's used for ancient traits reappearing.

NARRATOR: But is such a thing possible? Can a genetic defect make a modern human exhibit ancient characteristics? It can certainly seem that way. People are born with excess hair and monkey-like tails. Or extra nipples, they're even more common, found, as in dogs, along the so-called milk line, running between armpit and groin.

But, although such traits may seem to emerge from the past, research suggests otherwise, research that began with a fruit fly, stricken by a very odd genetic defect.

SEAN CARROLL (University of Wisconsin-Madison): And it's causing the appearance of pretty decent looking legs in place of antennae. So, legs on top of the head—that's not where legs normally belong. And so what biologists wanted to understand was, "How could mutations in a single gene put sort of the right body part, but in the wrong place?"

NARRATOR: Researchers began tracking genetic mistakes in the fruit fly. In addition to insects with legs coming out of their heads, there were flies without wings or eyes. One by one, scientists identified the genes involved in building the insect. They had assumed the genetic recipes for making a fly and making a human would vary widely, but as their research progressed, they found something quite startling.

SEAN CARROLL: The unexpected revelation was that these very same genes that build fruit fly body parts, build our body parts, mouse body parts, snake body parts, worm body parts, and the body parts of essentially all animals throughout the animal kingdom. So that was really a shocking revelation to biologists, because the expectation was, you know, very different animals, we thought, would be built with different sets of genes. But the answer really is no.

NARRATOR: Mutant fruit flies had revealed that animals use the same set of master genes to build their bodies, genes inherited from a common ancestor that lived over half a billion years ago.

These master genes also determine the striking differences between species, by governing how other genes switch on and off. But sometimes the switching goes awry. And that's how features appear that may seem like ancient traits.

SEAN CARROLL: These mutations are disrupting some of the choreography of development. So it's not some sort of throwback to an ancient ancestor. This is just a malfunction of the instructions these genes are receiving.

NARRATOR: Like Sean Carroll, Nick Humphrey also doubts that the handwalkers represent a genetic devolution.

NICHOLAS HUMPHREY: It would seem, to me, extremely improbable that a single genetic mutation has thrown us back to an earlier way of behaving. I'm not going make any bones about this. I think that Professor Tan's description of this family as a devolution, as an evolutionary throwback, is not only scientifically irresponsible, but deeply insulting to this family.

NARRATOR: Irresponsible and insulting, Humphrey believes, because the family is already stigmatized, as Resit is well aware.

DEFNE ARUOBA: He's worried that you may be comparing and contrasting these individuals with other species on TV.

NICHOLAS HUMPHREY: Clearly, people in this part of the world have a very different picture of the origin of human beings. Do you understand what it is?

DEFNE ARUOBA: I understand that it has a lot to do with how Islam believes we all came from Adam and Eve, and if somebody proves, or if a science is claiming that we evolved from apes, it opposes that kind of thinking. So that's why people are very sensitive.

NARRATOR: Even the military police show up, fearing the scientists will compare the family's gait to animals. Insulting Turks is a criminal offence here. The soldiers threaten to use force if the scientists don't leave. It takes all of Defne's powers of persuasion to get permission to stay.

Allowed to continue working, the scientists take the family to a local hospital for brain scans. The way the affected siblings move suggests that something has interfered with how their brains have developed.

Safiye cries out in anguish after the staff removes her headscarf. Although she's frightened by the experience, Resit hopes these tests may explain why his children have been born this way and perhaps offer them some practical ways to cope with the condition.

Nick brings the M.R.I. scans to Cambridge, where he asks an old friend to interpret the results.

Roger Keynes is a neuroscientist with a special interest in how brain disorders affect walking.

NICHOLAS HUMPHREY: Well, this is Huseyin's brain.

ROGER KEYNES (University of Cambridge): Okay, so we are looking at the brain sideways on, starting up here, with the head looking forward this way. You can see the eye socket and the nose there. And as you come across to the other side, just going straight through a series of sections of the brain to the other side, you can see the brain stem, the stalk of the main brain here. And at the back of the brain stem, is this piece of the brain called the "cerebellum," the little brain. There is something very striking which hits you, immediately you see it. It's very clear that in the middle of the cerebellum here, what's called the's shrunk.

NARRATOR: Huseyin has marked brain damage.

NICHOLAS HUMPHREY: Supposing we were to look at a normal brain?

ROGER KEYNES: Yes, I've got one right here. It's on a bigger scale, but it, I think, makes the main point that here, in the mid-line of the brain, you can see the cerebellum normally sized, no loss of tissue at all.

This is Hacer, and same view, same problem. You can see it very clearly.

The cerebellum is a pretty ancient part of the brain. Fishes have a cerebellum. It helps them balance and stops them flopping over to one side when they are moving along. And we have a bigger cerebellum, in conjunction with our brain expansion—the forebrain expansion—but it has, essentially, the same kind of function. It helps us balance and walk upright and walk steadily, and also coordinates our movements, normally.

NICHOLAS HUMPHREY: What would you expect to find as a result of the cerebellar damage?

ROGER KEYNES: I'd expect them to have their feet quite wide apart as they tried to walk and then to stagger in either direction, as they actually walk.

NARRATOR: Exactly as Gulin does; Hacer, too, mostly walks upright in the same way. But what about the others who can only walk on all fours?

Last year, Italian scientists reported on this young man. Doctors could hardly believe their eyes when they saw his brain scans. He has no cerebellum at all, and yet he can still walk.

NICHOLAS HUMPHREY: The damage to the cerebellum is not likely to explain why they're quadrupedal. Has that ever been seen before?

ROGER KEYNES: Not to my knowledge, no.

Okay, so this is a normal human brain, and here is the cerebellum, one hemisphere on one side and one hemisphere on the other side. The cerebellum is a very complicated piece of brain. There are lots of genes that build it, and we are only scratching at the surface, at the moment. Some of these genes that build the cerebellum are known now. And this gene—as it undoubtedly is, this abnormal gene—in this family, I think will be identified sooner or later. And, no doubt, it will turn out to be a piece in the story of how the cerebellum is built. Whether it's more than that, whether it's a gene that helps you stand up, I think, is likely to be a gross over-simplification.

NARRATOR: But 600 hundred miles away, in Berlin, the handwalkers have inspired quite a different reaction.

Here at the Max Planck Institute, Stefan Mundlos believes their genes may indeed hold clues about how we came to walk upright. The secret may lie in these samples of the family's blood sent by Turkish scientists. Cells in their blood contain genes, and one of these genes, Mundlos believes, carries a mutation causing the disorder. A mutation is a random change in the chemical structure of a gene that may be beneficial, harmful or neutral. Most of us carry dozens of harmful mutations, but, because we inherit two copies of each gene, one from each parent, the normal gene keeps us healthy. But when close relatives marry, their child may inherit two defective genes.

STEFAN MUNDLOS: This defective gene has to come from both parents. So, within one family, you basically compare the DNA, looking for a region which is identical. And it is identical, because this person has inherited the same chromosome from the father as from the mother.

NARRATOR: After months of toil, the team has narrowed the search to a patch of DNA on chromosome 17, unique to the handwalkers. They must now hunt through this region of about 120 genes to find the mutation. It's a time-consuming process, but Mundlos believes it's worth it, that success may lead to far more than just an explanation of what went wrong in five individuals.

STEFAN MUNDLOS: I think, basically, what is happening here is that this gene controls a very important regulatory process. And once we have identified the gene, then we can possibly learn something about the evolution of bipedality and the role of certain genes in the evolution of this very human trait.

NARRATOR: What justifies his optimism? Parallel cases. Across the world, human beings suffering from rare mutations appear to be offering science a new window into evolution.

The first cases showed up in London, in the late 1980s. Three generations of the Kearney family had difficulty with language, from pronouncing words to putting them in the right order. Analysis of the family's DNA led to a gene called FOXP2. A mutation in the gene was causing the problem.

The discovery caught the attention of geneticists at the Institute for Evolutionary Anthropology in Leipzig, Germany. Svante Pääbo and Wolfgang Enard wondered if the mutation in FOXP2 helped make humans human.

WOLFGANG ENARD (Max Planck Institute): It was the first time a single gene was linked to this human-specific trait of speech and language. And, obviously, one knows, of course, right, human speech and language is such a unique trait that somehow, somewhere in our genomes, changes must have taken place, during human evolution, that enables us to learn speech and language as easily as we do now.

NARRATOR: To see if changes in FOXP2 gave humans an evolutionary advantage, Wolfgang and Svante decided to compare the gene across animal species.

SVANTE PÄÄBO (Max Planck Institute): Studying DNA is exciting to me, I think, because, in a way, it is like making an archaeological excavation. But you don't do it in a cave somewhere, you do it in our genes. And you find out things about our ancestors that we cannot find out any other way—that the bones and the stones will not tell us.

NARRATOR: The Leipzig team first looked for the FOXP2 gene in the DNA of mice. The assumption was that, since mice don't speak, they should have a very different FOXP2 gene, or even lack one.

WOLFGANG ENARD: We were really struck by the findings, because it was not only that the mouse has a FOXP2 gene, but it is also very, very similar to the human one. So, it is one of the most similar ones, actually, if you compare genes from...all genes from humans and mice. And we were very disappointed, because we thought a language gene...I mean, that should change a lot, right? Because it should be...look very different in the mouse.

NARRATOR: Perplexed, the team then compared the gene in humans and the great apes. Suddenly things became more interesting. In 70 million years of evolution, FOXP2 had changed its structure significantly only three times. But two of those changes occurred in just the last 200,000 years, long after our ancestors split off from chimpanzees and during the time when language, in its present form, is thought to have emerged.

SVANTE PÄÄBO: It's a good hypothesis—but still just a hypothesis—that something happened to this gene in our recent evolution that may, then, have had to do with our ability to vocalize better.

NARRATOR: Although it's still unclear what FOXP2 actually does in the body, one thing is certain, everyone alive today has virtually identical FOXP2 genes. And this means these two key mutations were so advantageous that, when they appeared, they swept through the human race. If you didn't have them, you simply could not compete.

Inspired by the story of FOXP2, researchers began to probe a condition which strips away another key human characteristic. It's called microcephaly; and, in Boston, Dr. Christopher Walsh examines one of its victims.

CHRISTOPHER WALSH (Children's Hospital Boston): Is breathing generally okay during the day?

DIAMANNI'S MOTHER: Sometimes, when he gets startled, it'll go up fast, like "huh, huh, huh," but then he calms himself right back.

NARRATOR: Microcephaly means "small head." Its impact is dramatic.

CHRISTOPHER WALSH: Poor Diamanni is about seven years old now, but really still can't even stand, can't get out of the chair. And, so, he really only has about the cognitive level of about a nine-month-old baby.

NARRATOR: M.R.I.s reveal that Diamanni's brain is about half the size of a normal child's and similar in size to the brain of our ancestor, Lucy, a connection that intrigues Walsh.

CHRISTOPHER WALSH: We know that two or three million years ago, our human ancestors had a brain that was only about half the size of modern humans. And it seems like, in a very short time by evolutionary standards, a heartbeat by evolutionary standards, the brain doubled in size. So we thought that genes involved in microcephaly might be important for evolution, because we know that they control one of the most important differences between our brain and other animals.

NARRATOR: Like language and standing upright, our large brain size sets us apart from other primates. But did these genes, which, when damaged, cause microcephaly, play a role in evolution?

In 2002, Walsh's team finds a microcephaly gene called ASPM. When it shuts down, the brain grows to only half its normal size. Taking their lead from FOXP2, Walsh and other scientists now look at how ASPM has changed in animals as they evolve.

CHRISTOPHER WALSH: So how can you tell that a gene is a target of evolution? The way you do that is by asking if that gene has changed more than the average for all of the others, between chimps and humans, for example. So, when we looked at ASPM, we find that it really stands out, between chimps and humans, as a gene that changed much more than the average.

NARRATOR: In other words, at the same time our ancestors' brains were expanding the most, ASPM was changing the most. But does that mean that this gene played role in evolution? Perhaps, but not necessarily.

SEAN CARROLL: Mutations in single genes can have dramatic effects, and they stun us. But that does not mean that evolution involved that gene, whatsoever, with respect to some change in that trait. It's very easy to knock down a house and very hard to build it up. So, it may have contributed to brain-size evolution, but we don't know whether it might have contributed one percent, five percent, 10 percent, 50 percent of the change in brain size, because there's so many genes that affect brain size.

CHRISTOPHER WALSH: So we're really faced with two huge tasks. We have a human brain which is unbelievably complicated, and we have a human genome which is unbelievably complicated. And we know that there are 10,000 genes expressed in the brain, and nature put them all there for some good reason. Problem is, we don't know what most of those genes do yet. And so we don't know how to relate the evolutionary changes to the actual function of the genes. And that's where it's important to study genetic disease in humans, because diseases in humans tell you what the genes do.

NARRATOR: Rare genetic mutations have helped scientists associate specific genes with brain size and language. Now, Stefan Mundlos hopes the handwalkers will lead him to a gene associated with bipedality. It is the third key human trait, and, as Brian Richmond explains, no less complicated than the other two.

BRIAN RICHMOND: For our ancestors to stand upright on two legs, many changes occurred throughout the skeleton. For example, our knees are brought in line so that our feet are underneath our body, which allows us to walk in a smooth way instead of waddling. Our legs are much longer, which gives us a greater stride, which gives us a more efficient gait. And even at the base of the skull...the spinal cord emerges from the bottom of the skull instead of the back of the skull, because our heads are now tilted to look forward on this upright body. Now, all of these changes could not occur with a single gene.

SEAN CARROLL: So, if you were reading through the human genome, you wouldn't be reading genes that said, oh, "thumb, pinky, bipedality, speech, etc." No. These are traits put together by common sets of genes, large numbers of them, working together.

NARRATOR: And what about the role of environment? That's what Nick Humphrey has returned to Turkey to explore. He and Defne Aruoba interview the father, hunting for clues that may explain why his children never walked upright.

DEFNE ARUOBA: This is God's test on him. These children are God testing him. And after he dies, God will make sure that he and the children are being taken care of, because they did their deeds in this world, in this life.

NARRATOR: It is still a simple way of life here. The quadrupeds shelter indoors, driven by the seasons, poverty, and a Muslim faith which teaches acceptance.

Nick believes the answer to the scientific puzzle will turn out to lie here, in the very fabric of the family's life.

The next morning, Nick and Defne discover something new about the family. As babies, all 19 children crawled as usual, on their hands and knees. Then, at about 10 months, every single one of them started walking on their feet and hands. It's called a bear-crawl. And, occasionally, babies do crawl this way. Here's a perfectly healthy child showing how it's done.

The picture begins to fall into place for Nick.

NICHOLAS HUMPHREY: I'm quite certain that the key lies in the local culture in which these children were brought up. Many things were strange about them. We know for a start, from what the mother told us, that they crawled in an unusual way. Some of them, certainly, then had this extraordinary balance problem. We know the mother was producing babies in extraordinary rapid succession. Seven children were born within five years. Four of those children went on to be quadrupeds. She must have been totally overwhelmed.

NARRATOR: Notwithstanding her obvious love for them.

DEFNE ARUOBA: She said "they are my insides." "Ciger" in Turkish is lung or liver, so, like, the most intimate inside organs. That's what she called them.

NICHOLAS HUMPHREY: In North America or in Britain, for that matter, any child who crawled on...after the age of two or three, was crawling on four legs, would be taken off to the doctor. They would be given physiotherapy, they would given special training, and so on. And, no question, they would be on two legs within a year or two. They might be still shaky a bit, but, nonetheless, that's...they would be bipeds.

NARRATOR: Although the siblings probably don't know of opportunities they might have had elsewhere, their acceptance of their situation has its limits. Huseyin's frustration often escalates into anger. The one member of the Ulas family able to calm him down is Wolf, their dog.

And Safiye often withdraws into herself.

Moved by this obvious suffering, Defne has had enough of theories.

DEFNE ARUOBA: Yeah, I mean, I don't really care about finding out what is the source of this, what is the reason for that, so I'm more interested in possible remedies.


DEFNE ARUOBA: What can be done? What needs to be done? And what do these people need?

NARRATOR: Nick raises a tantalizing possibility. If their environment helped to produce the handwalkers, could changes in that environment transform them, even now?

The scientists call Dr. Ali, a local physical therapist. Dr. Ali doesn't hold out much hope that Huseyin will ever walk upright, unaided. He thinks it is too late for him. But he believes that, with therapy, the younger girls might be helped.

Dr. Ali has brought with him a simple, $30 walking frame. Astonishingly, no one has ever thought to give them one before, and so no one has seen what a difference it could make.

The possibility of being able to walk upright raises new hope in the family, encouraged further, when Nick and Defne erect a set of parallel bars in the yard.

RESIT ULAS (Father of quadrapedal children/translated by Defne Aruoba): A big thing, a huge thing.

NARRATOR: Resit says he would give everything, even the clothes off his back, if his children were able to walk without using their hands.

NICHOLAS HUMPHREY: I don't think we should be surprised at all, although this is an extreme case of it, that culture can be so influential. We're increasingly realizing that so little of our behavior as children or as adults is actually programmed by the genes. The genes give us certain potentials and they interact with the culture we're in.

NARRATOR: The younger girls seem content. But there's no doubt they'd love to lead normal lives. Hacer tells us that if she could walk properly she could go to dances and meet a husband.

DEFNE ARUOBA: Yeah, she would love to go to her own wedding.

NARRATOR: It is almost time for Nick and Defne to leave. They suggest the family take some time off from their physical therapy for a trip to the beach. It is only an hour away, but none of them have ever seen the sea before.

Sometimes, when the handwalkers leave their home, they attract unwelcome attention. But today, far from the public eye, they revel in the sand and the surf.

Resit hopes the attention of the scientists will bring as much help as possible for his children, and perhaps a little understanding, too.

"It's beautiful," says mother, Hatice. "I didn't know Allah had created such beauty."

Recently, other handwalkers have been found around the world, some perhaps with the same syndrome as the Ulas family. But a responsible gene has still not been identified, and the controversy over what causes people to walk on all fours remains unresolved.

SEAN CARROLL: I think a huge question we're to confront in understanding human behavior is how much is genetically hardwired and how much is environmental or culturally effective. And the handwalkers might, eventually, tell us something about human evolution. But these first human genes being studied in depth, those that affect brain size, those that affect language, those that affect locomotion, in this case, or cerebellum development, these are the first few stars in the telescope that we can see, the first few stars in the human genome that we can see, but there are thousands more to investigate.

NARRATOR: January, 2006: For over a year, the Ulas family has exercised on the parallel bars that Nick and Defne erected. Dr. Ali has warned there is no quick fix; that it could take months more, and even then, they may never walk unaided. But it has given the family hope. Emos has lost pounds and loves showing off her new balance skills. But there is no sign of Huseyin. Dr. Ali didn't think he would ever walk upright, and, at first, it looks as if he doesn't bother trying. But then he appears, proving that this family has something vital, indeed, to tell us about being human.

On NOVA's Family That Walks on All Fours Web site, hear from psychologist Defne Aruoba how her time with the Ulas family changed her worldview. Find it on

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Family That Walks on All Fours

Produced and Directed by
Jemima Harrison and Sarah Holt

Director of Photography
Jon Lane

Narrated by
Kathryn Walker

Associate Producers
Ethan Herberman
Julie Rosenberg

Edited by
Sarah Holt

Darren Hercher
Stephen McCarthy
Erich Roland
Andreas Bremer
Richard Cook

Sound Recordists
Len Schmitz
George Shafnacker
Markus Brodt
Cameron Mercer

Writer for the BBC
Jemima Harrison

Michael Bacon


Voice Over
Aslan Chopoorian

Online Editor and Colorist
Mark Steele

Audio Mix
John Jenkins

Sound Editors
Robb Todd
Anju Rege

Archival Research
Elizabeth Ashe

Additional Research
David Boardman

Production Assistants
Justin Daering
Chloe Hayward

Yasemin Isler

Consultants, Turkey
Defne Aruoba
Cetin Mursalioglu

Archival Material
BBC Motion Gallery
Ennion Del Giudice
F. Rudolph Turner, Indiana University
Jude Stringfellow
New Scientist
Robert Van Winkle
Stanley B. Burns, MD
The Burns Archive
Vulcan Productions, Inc.
Wired Magazine
World Science

Special Thanks
Anne Sauer, Tufts University
Children's Hospital Boston
Daniel Petry
Daniel Schmitt, Duke University
Dean Falk, Florida State University
Dr. Owen Lovejoy, Kent State University
Ian Tattersall
Infant Action Lab
Kaushik Murali
Nathan D. Ritsko
Robert Eckhardt, Penn State University
Russell Tuttle
Shirby Simmons
The Ulas Family

Executive Producer for the BBC
Richard Klein

NOVA Series Graphics
yU + co.

NOVA Theme Music
Walter Werzowa
John Luker
Musikvergnuegen, Inc.

Additional NOVA Theme Music
Ray Loring

Post Production Online Editor
Mark Steele

Closed Captioning
The Caption Center

NOVA Administrator
Ashley King

Eileen Campion
Anna Lowi

Gaia Remerowski

Production Coordinator
Linda Callahan

Unit Managers
Carla Raimer

Raphael Nemes

Legal Counsel
Susan Rosen Shishko

Assistant Editor
Alex Kreuter

Associate Producer, Post Production
Patrick Carey

Post Production Supervisor
Regina O'Toole

Post Production Editor
Rebecca Nieto

Post Production Manager
Nathan Gunner

Supervising Producer
Stephen Sweigart

Producer, Special Projects
Susanne Simpson

Coordinating Producer
Laurie Cahalane

Senior Science Editor
Evan Hadingham

Senior Series Producer
Melanie Wallace

Managing Director
Alan Ritsko

Senior Executive Producer
Paula S. Apsell

Passionate Productions For BBC

Produced for NOVA by Holt Productions, LLC

© Passionate Productions MMVI

Family That Walks on All Fours Additional Material © 2006 WGBH Educational Foundation

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