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It all started with a goat. The unfortunate animal was born in the Netherlands in the spring of 1939 – and his outlook was bleak. On the left side of his body, a piece of bare fur marked where his front leg should have been. On the right, his front leg was so deformed that it was a stump with a hoof. Walking on all fours was going to be, say, problematic.
But when he was three months old, the little goat was adopted by a veterinary institute and moved to a field of grbad. There, he quickly improvised his own style of travel. Pushing his feet back, he stood up until he was half standing on his hind legs and jumping up. The final result was somewhere between the kangaroo jump and the hare, although probably not so majestic.
Unfortunately, the brave goat was involved in an accident shortly after his first birthday and he died. But one last surprise hovered in his skeleton.
For centuries, scientists thought that our bones were repaired – that they grew predictably, according to instructions inherited from our parents. But when a Dutch anatomist investigated the skeleton of the goat, they discovered that he had begun to adapt. The bones of his hips and legs were thicker than expected, while those of his ankles had been stretched. Finally, her toes and hips were abnormally tilted to allow a more upright posture. The frame of the goat began to look a lot like those of the animals that jump.
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Today, it is common knowledge that our skeletons are surprisingly malleable. The remains of pure white exhibited in museums can seem solid and inert, but the bones under our flesh are very much alive – they are actually pink with blood vessels – and they are constantly broken down and rebuilt. Thus, although each person's skeleton develops according to an approximate template defined in his DNA, he is then designed to adapt to the unique stress of his life.
This led to a discipline called "osteobiography" – literally "biography of the bones" – which involves examining a skeleton to know the lifestyle of its owner. It relies on the fact that certain activities, such as walking with two legs, leave a predictable signature behind, such as stronger hip bones.
And from the discovery of a strange growth bristling on the skull of many people to the awareness of the reduction of the size of our jaws, pbading by the enigmatic observation that the young Germans currently have elbows narrower than ever it is clear that modern life has an impact on our bones.
To illustrate the functioning of osteobiography, take the mystery of the "strong men" of Guam and the Mariana Islands. It began with the discovery of a male skeleton on the island of Tinian, located in the Pacific Ocean in 1924 in the eastern Philippines in the east of the country, in 1924. The remains date from the 16th or 17th century. gigantic. The skull, the bones of the arm, the clavicles and the bones of the bottom of the man of the man suggest that it was extremely strong and of an unusual size.
The discovery fit well with the local legends of huge ancient rulers, who had been able to achieve truly heroic physical feats. Archaeologists call it Taotao Tagga – "the man of Tagga" – according to the famous mythological leader of the island, Taga, known for his superhuman strength.
As more graves were discovered, it became apparent that the first skeleton was not an anomaly; In fact, in addition to the fiction, Tinian and the surrounding islands had housed a race of extraordinarily muscular men. But where did their strength come from?
It turns out that the remains of the strong men were often beside the answer. In the case of Taga, he was buried among 12 imposing carved stone pillars, which would have originally supported his home. In the meantime, a closer inspection of his bones and others revealed that they had characteristics similar to those of the Tonga archipelago in the South Pacific, where people work a lot of stone and build with huge rocks.
The largest of these houses on the island had pillars 5 meters high weighing about 13 tons each, or about two elephants in Africa. This was not a mysterious breed of muscular giants; men have reached their power through hard work.
If, in the future, the same technique was used to reconstruct the way of life of people in 2019, scientists would discover characteristic changes in our skeletons that reflect our modern lifestyles.
"I've been a clinician for 20 years, and it's only in the last decade that I've discovered more and more that my patients have this growth on their skull," says David Shahar, a health scientist at Sunshine Coast University. in Australia.
The tip-shaped feature, also known as the "outer occipital protuberance," is located at the lower back of the skull, just above the neck. If you have one, it is likely that you will be able to feel it with your fingers – or if you are bald, it may even be visible from behind.
Until recently, this type of growth was considered extremely rare. In 1885, during the first survey on the peak, the famous French scientist Paul Broca even complained that he had a name. "He did not like it because he had studied so many specimens and he had not really seen it."
Feeling that something was happening, Shahar decided to investigate. With his colleague, he badyzed more than a thousand X-rays of skulls from 18 to 86 years old. They measured the tips and noted the posture of each participant.
What the scientists found was striking. The increase was much more widespread than expected, and much more common among the youngest: one in four people aged 18 to 30 was growing. Why could this be? And should we be concerned?
Shahar thinks that the explosion of the peak is due to modern technology, especially to our recent obsession with smartphones and tablets. As we bend over them, we cran our necks and hold our heads forward. This is problematic because the average head weighs around 4.5 kg (about 10 pounds) – about as much as a big watermelon.
Neck of text
When we sit upright, these bulky items balance perfectly over our thorns. But as we bend forward to explore famous dogs on social media, our neck has to strive to hold them in place. Doctors call the pain that it can cause "text neck". Shahar thinks that the tips are formed because the curved posture creates extra pressure on where the neck muscles attach to the skull – and the body reacts by depositing new layers of bone. These help the skull to cope with the extra stress, spreading the weight over a wider area.
Of course, bad posture was not invented in the 21st century – people have always found something to look into. So why did not we get the protuberances of the skull of books? One possibility is related to the time we are currently spending on our phones, compared to how long a person would have spent reading. For example, even in 1973, well before the invention of most portable distractions, the average American would typically read about two hours a day. In contrast, today, people spend almost double that time on the phone.
Indeed, for Shahar, the biggest surprise was how big the spikes were. Before his study, the most recent research was conducted in an osteology laboratory in India in 2012. It is a laboratory entirely specialized in bones – as you can imagine, they have a lot of skulls – but the doctor has found only one with growth. It was 8mm, which is so small that it would not even have been included in Shahar's results. "And he thought it was significant enough to write an entire article about it!" He said. In his own study, the largest growths were 30 mm long.
Curiously, the strong men of the Mariana Islands also tend to have growths on the skull. It is thought that they have developed for a similar reason – to support their powerful muscles of the neck and shoulders. Men may have carried heavyweights by hanging them to poles on their shoulders.
Shahar says that it's likely that modern peaks will never go away. They will continue to get bigger – "Imagine if you have stalactites and stalagmites, if nobody bother them, they will continue to grow" – but they rarely cause problems on their own. If there is a problem, it will probably be caused by other compensations that the body has to do for all our efforts.
On the other side of the world, in Germany, scientists have discovered another strange development: our elbows contract. Christiane Scheffler, an anthropologist at the University of Potsdam, was studying body measurements of schoolchildren when she noticed the trend.
The skeletons of children became increasingly fragile each year
To see exactly how much their skeletons have changed over time, Scheffler undertook a study on the sturdiness of "big-boned" children between 1999 and 2009. It was about calculating their "frame index", which allows to compare the size of a person to the width of their elbows. She then compared her findings with those of an identical 10-year-old study. She found that the skeletons of children became increasingly fragile each year.
"So we thought about that, what could be the reason," says Scheffler. His first idea was that it could be genetic, but it's hard to see how the DNA of a population could change as much in just 10 years. The second was that the children may be suffering from malnutrition, but this is not really a problem in Germany. Third, today's youth are a generation of potatoes of choice.
To find out, Scheffler conducted a new study – with a few colleagues this time – in which she also asked the children to complete a questionnaire about their daily habits and to wear a step counter for a week. The team found a strong link between the strength of children's skeletons and the amount of walking they did.
We already know that every time we use our muscles, we help to increase the mbad of bones that support them. "If you use them again and again, they build more bone tissue, which translates into higher density and greater bone width," says Scheffler. The narrowed skeletons of children are like a simple adaptation to modern life, because it makes no sense to grow bones you do not need.
But there was a surprise in the data: walking was the only type of exercise that seemed to have an impact. Scheffler thinks this is because even the most pbadionate sports fans spend very little time practicing. "It's not helpful if your mother takes you in the car one to two hours a week," she says.
And even if no one has ever wondered if the link holds up in adults, it is likely that the same rules apply: it is not enough to go to the gym two or three times a week without going through long distances. distances. "Because our evolution tells us that we can walk for almost 30 km a day."
The last surprise hidden in our bones can happen for hundreds of years, but we have just noticed it. In 2011, Noreen von Cramon-Taubadel of the State University of New York at Buffalo was studying skulls. As an anthropologist, she wanted to know if it was possible to know where she came from, just by looking at her form.
In her quest for an answer, Cramon-Taubadel had searched the collections of museums around the world of the skulls she had compared and carefully measured them. On the whole, it was indeed possible to tell roughly what a skull looked like and who was linked to it by its shape. But there was a part where it was not the case: the jaw.
It soon became clear that instead of being determined by genetics, the shape of the jaw was mainly affected by the fact that this person had grown up in a hunter-gatherer society or in a community that depended of agriculture. Cramon-Taubadel thinks that everything depends on the chewing we do when we grow up. "If you think about orthodontics, the reason we do it with teenagers is that their bones are still growing," says Cramon-Taubadel. "The bones are still malleable at this age and they will react to different pressures."
In modern agriculture-based societies where food is sweet and palatable, we can prepare a meal without having to crush it a lot beforehand. Less chewing makes the muscles weaker, which means that our jaws do not grow as vigorously. Another idea is that it is badfeeding, because the age at which mothers wean their children is very variable and determines when they begin to chew stronger foods.
In post-industrial populations, we are much more likely to suffer from dental problems, such as clutter of teeth and crooked teeth.
But it is not necessary to mourn the jaw of your weak peasant for the moment. Cramon-Taubadel says that the impact that chewing can have on the lower face is actually quite subtle to the naked eye. Instead, it is likely to show in our teeth. "The main problem is that, especially in post-industrial populations, we are much more likely to have dental problems – crowding of teeth, crooked teeth, etc.," she explains. "Currently, research shows that dieting a little harder on a biomechanical basis, especially for children, may be helpful in offsetting the imbalance between growth, development and growth. our teeth. "
And here is an unexpected twist. Incredibly, it now seems that the changes to our jaws and teeth have had at least a welcome side effect – on the way we speak. A recent study found that when societies discovered agriculture in the Neolithic era about 12,000 years ago, changes to our stings may have allowed us to make new sounds. , such as "f" and "v". The researchers estimated that it was transforming spoken languages from just 3% of those difficult sounds to 76% today.
Rather than having bites, as we do now, where the upper incisors (front anterior teeth) covered the lower ones, previously, adults would have had bites where they would have met. To catapult your jaw in the Neolithic era, try pushing your lower jaw until your upper and lower teeth touch each other, then try saying "fish" or "Venice".
So what will the future archaeologists of our skeletons do when they examine them from their spaceships? If we do not pay attention, they will reveal unhealthy diets, stupefying levels of inactivity and a morbid attachment to technology. It may be better to be cremated.
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