How modern life is transforming the human skeleton
Author: Zaria Gorvett
Source: BBC (http://www.bbc.com/future/story/20190610-how-modern-life-is-transforming-the-human-skeleton)
The human body doesn’t cease to fascinate especially its malleability. For centuries, scientists believed that our bones were fixed and that they grow in a predictable way depending upon the genes we inherit from our parents. However, a Dutch scientist‘s investigation of a goat’s skeleton which had one leg missing & one leg deformed by birth changed the myth that our bones are fixed. He found that goat’s bones had started to adapt his body structure – “The bones in his hips and legs were thicker than you would expect, while the ones in his ankles had been stretched out. Finally, his toes and hips were abnormally angled, to accommodate a more upright posture. The goat’s frame had started to look a lot like those of animals which hop.”
Osteobiography – literally “the biography of bones” – involves looking at a skeleton to find out how its owner lived. Research shows that men in 16th/17th century were very strong and the reason men achieved their powerful builds by sheer hard work. Zaria refers to a health scientist’s work to highlight more recent developments in the human skeleton – a spike-like feature found at the lower back of the skull, just above the neck and attributes it to the amount of time spent on smartphones. Furthermore, she cites, Christiane Scheffler’s work which shows that children’s skeletons are becoming more & more fragile each year and suggests a straightforward adaptation to modern life – since it doesn’t make sense to grow bone that you don’t need.
“…So what will future archaeologists make of our skeletons, when they examine them from their spaceships? If we’re not careful, they’ll reveal unhealthy diets, staggering levels of inactivity, and a morbid attachment to technology. Perhaps it’s best to be cremated.”
“Today it’s an established fact that our skeletons are surprisingly malleable. The pure white remains displayed in museums may seem solid and inert, but the bones beneath our flesh are very much alive – they’re actually pink with blood vessels – and they’re constantly being broken down and rebuilt. So although each person’s skeleton develops according to a rough template set out in their DNA, it is then tailored to accommodate the unique stresses of their life. This has led to a discipline known as “osteobiography” – literally “the biography of bones” – which involves looking at a skeleton to find out how its owner lived. It relies on the fact that certain activities, such as walking on two legs, leave a predictable signature behind, such as sturdier hip bones. And from the discovery of a curious spiky growth on the back of many people’s skulls to the realisation that our jaws are getting smaller, to the enigmatic finding that German youths currently have narrower elbows than ever before, it’s clear that modern life is having an impact on our bones.
For an example of how osteobiography works, 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, which lies 1,600 miles (2,560km) east of the Philippines in the Pacific Ocean, in 1924. The remains were dated to the 16th or 17th Century, and they were positively gigantic. The man’s skull, arm bones, collarbones, and the bones of his lower legs suggested that he had been immensely strong and unusually tall. The finding slotted in nicely with local legends of enormous ancient rulers, who had been capable of truly heroic physical feats. Archaeologists called him Taotao Tagga – “man of Tagga” – after the island’s famous mythological chief Taga, who was renowned for his super-human strength. As other graves were discovered, it became clear that the first skeleton was no anomaly; in fact as well as fiction, Tinian and the surrounding islands had been home to a race of extraordinarily brawny men. But where had they got their strength from? …..This was no mysterious race of muscular giants; the men achieved their powerful builds by sheer hard work.
If, in the future, the same technique were used to piece together how people lived in 2019, the scientists would find characteristic changes in our skeletons that reflect our modern lifestyles. “I have been a clinician for 20 years, and only in the last decade, increasingly I have been discovering that my patients have this growth on the skull,” says David Shahar, a health scientist at the University of The Sunshine Coast, Australia. The spike-like feature, also known as the “external occipital protuberance” is found at the lower back of the skull, just above the neck. If you have one, it’s likely that you will be able to feel it with your fingers – or if you’re bald, it may even be visible from behind.
…Shahar thinks the spike explosion is down to modern technology, particularly our recent obsession with smartphones and tablets. As we hunch over them, we crane our necks and hold our heads forward. This is problematic, because the average head weighs around 10 pounds (4.5 kg) – about as much as a large watermelon.
When we’re sitting upright, these hefty objects are balanced neatly on top of our spines. But as we lean forwards to pore over famous dogs on social media, our necks must strain to hold them in place. Doctors call the pain this can cause “text neck”. Shahar thinks the spikes form because the hunched posture creates extra pressure on the place where the neck muscles attach to the skull – and the body responds by laying down fresh layers of bone. These help the skull to cope with the extra stress, by spreading the weight over a wider area. Of course, bad posture was not invented in the 21st Century – people have always found something to hunch over. So why didn’t we get the skull protuberances from books? One possibility is down to the sheer amount of time that we currently spend on our phones, versus how long a person would previously have spent reading. For example, even in 1973, well before most modern hand-held distractions were invented, the average American typically read for about two hours each day. In contrast, today people are spending nearly double that time on their phones. Indeed, for Shahar, the biggest surprise was just how large the spikes were. Before his study, the most recent research was conducted at an osteological lab in India, in 2012. That’s a lab specialising entirely in bones – as you can imagine, they have quite a lot of skulls – but the doctor there only found one with the growth. It measured 8 mm, which is so small, it wouldn’t even have been included in Shahar’s results. “And he thought it was significant enough to write a whole paper about it!” he says. In his own study, the most substantial growths were 30mm long.”