Science knows why...
1 You get goose bumps.
When you feel a chill or see something scary, your body releases a surge of adrenaline. The point is to make your body hair stand up—which helped our animal ancestors stay warm and also made them look larger in the face of predators. Getting those individual hairs to stand to attention requires the teeny skin muscles at the base of each follicle to contract, making your skin look vaguely like a goose’s post plucking—hence, goosebumps.
2 You grow wisdom teeth.
Wisdom teeth are actually a third set of molars. They allowed our forebearers to munch on rough food such as roots, nuts, and meat, especially when other teeth fell out (alas, our ancestors had poor oral hygiene). About 35 per cent of people never develop wisdom teeth, partly because of an evolutionary shift that means the human jaw is often too small for them. The rest of us start developing them by age ten, though they don’t fully emerge until young adulthood, which is when we (allegedly) acquire some wisdom.
3 Your fingers and toes wrinkle in water.
When you’re in the bath, water seeping into your skin makes the upper layers swell. That causes the blood vessels below to constrict, which in turn causes some of the upper layers of skin to collapse. The irregular pattern of swelling and falling skin is what we see as wrinkles on our fingertips and toes.
4 Your knees crack after sitting for a long time.
The sounds you hear are probably caused by gas being released from the spaces between your joints—just like when you crack your knuckles. Meanwhile, muscles or tendons rubbing against your bones may also make your joints creaky. “We say motion is lotion,” Kim L Stearns, MD, an orthopaedic surgeon at Lutheran Hospital in Ohio, told the Cleveland Clinic. “When you’ve been sitting around, fluid in the joints doesn’t move. The more active you are, the more your joints lubricate themselves” and the less noise they will make. The popping shouldn’t alarm you unless it is accompanied by pain or swelling.
5 You get a stitch in your side from running.
Starting a new exercise routine can cause pressure to push up from the abdomen or down from the lungs onto the diaphragm muscle between them. This restricts blood flow and causes the irritated diaphragm to spasm. Once your body gets used to exertion, side stitches should cease.
6 Your stomach growls when you’re hungry.
When the receptors in the stomach walls sense an absence of food, they send out electrical waves. These cause the muscular walls of the stomach to squeeze and release, making a rumbling sound. You may also hear some sloshing as these contractions move water and stomach acid around inside.
7 You see spots after a camera flashes.
The photoreceptors in the back of your eye convert light into electrical impulses that are sent to the brain to produce the images you see. “When a camera flash goes off, it’s so bright that it overstimulates the photoreceptors,” Elaine Icban, an assistant professor of clinical optometry at the New England College of Optometry, told statnews.com. While the photoreceptors are recovering, your brain “sees” nothing and fills in the blanks with spots.
8 You sneeze when you look up at the sun.
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