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Twelve surprising facts about the human body
Medical research is mainly concerned with malfunctions in the human body. But our bodies are a miracle of nature, full of quirks and quiddities ranging from fingertips that regrow, outsourced digestive systems and scent receptors in our lungs—on to a veritable petting zoo in our belly buttons.
Anger not the best medicine
Caution advised! Throwing a temper tantrum increases the risk of heart attack by a factor of eight—and the danger can last several hours. Contrary to popular belief, blowing off steam is bad for our health, and trying to work off frustration by hitting a punching bag will only make us angrier.
Tears are a turn-off
When women cry, men lose interest: experiments have shown that sexual arousal in men diminishes when they smell women’s tears. It’s believed that the phenomenon is due to a previously unknown chemical messenger that men don’t consciously perceive.
Powerful posteriors
Compared to other primates, the buttocks of humans are generously endowed. Indeed, the gluteus maximus is the largest muscle in the body, and it’s what makes us so good at walking and running. In addition to the sheer strength it supplies, it also ensures stability. Whereas other bipedal animals—the kangaroo, for instance—have large tails to counterbalance their forward-leaning torsos, this task is performed by our dutiful derrières.
The hazard in our throats
The pathways for food and air converge in our throats. When we choke, food sometimes goes down the windpipe—oft-times with fatal consequences. The faulty design came about when our earliest ancestors evolved from water creatures to living on land, making a separation of food and air passages necessary. Because fish breathe water, they don’t have the problem.
Airy intestines
Only thirty percent of all intestinal gas is a result of digestion. The majority of air is swallowed when we eat and drink. Most of this gas is absorbed by the intestinal wall, transported to the lungs and eliminated when we exhale. Only a small amount takes the rear exit: on average, about forty millilitres of gas is passed fifteen times every day.
Birthing pains
Two typical traits of human beings aren’t very compatible: our upright gait and our large brains. While bipedal movement requires a narrow pelvis, a wide pelvis would be better for birthing babies with large heads. On average, the birth canal in humans is 2.5 centimetres too narrow, making labour very painful. In the past, this was a leading cause of maternal death—caesarean sections have helped to reduce the risks.
Supercharged brains
While it’s true that the brain expends quite a large percentage of the calories we consume, it’s highly efficient, requiring no more energy than an energy-saving bulb. That said, to simulate a human brain in all its complexity, we would need the electricity generated by several nuclear power plants.
Lungs can smell
Scent receptors aren’t limited to the nose: they’re also found in our lungs, although we don’t notice anything, as the smelling process happens unconsciously. When the lungs perceive a toxin in the air, they temporarily constrict the airways. It all happens without switching on the brain—and very fast.
Personal petting zoo
The human skin offers a natural habitat to all manner of creatures. On average, eighty kinds of fungi live on our heels, and a good sixty bacterial species dwell in our belly buttons. What’s more, a few hundred tiny mites live on our faces, where they feed on sebum secreted by our pores. But not to worry—they’re completely harmless.
Pre-digestion in the kitchen
Although the human gut is only half as big as the intestines in primates of a similar size, we have no problem digesting our food—because we cook it first. Our comparatively small jaws are also a consequence of outsourcing some of our digestion to the stovetop. An unpleasant side effect of our small mouths is that our wisdom teeth often don’t fit.
Regrowing fingers
If a salamander loses a leg, the entire limb will regrow. We humans aren’t so lucky. However, if the fingertip of a young child is severed, it will grow back without scarring as long as the wound hasn’t been stitched up. And even in adults, an injured fingertip will regenerate over time if the cut is covered in a special dressing.
Blood-cell factories
