Health
Discover facts about health. Small discoveries that change the way you see familiar things.
Health
Your irises work like camera apertures
Muscles in the iris change the size of the pupil: they narrow it in bright light and widen it in dim light. That opening controls how much light reaches the…
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A cell can change how it reads DNA without rewriting the letters
Chemical tags and the way DNA is packaged help determine which genes a cell uses. These epigenetic controls let cells with essentially the same genetic…
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An apple seed's coat changes what happens when you swallow it
The seed contains amygdalin, which can release cyanide when broken down. Chewing gives digestion access to the contents; accidentally swallowing a few intact…
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Why cooking carrots helps you absorb beta-carotene
Beta-carotene sits inside carrot cells, and cooking softens the walls that hold it. Your digestive system can then get to more of it—one reason cooked carrots…
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Your tailbone is a leftover from having a tail
The tailbone, or coccyx, is the small remnant of an ancestral tail. It still sits at the bottom of the spine, so landing hard on it—like on an icy…
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Vestibular systems calculate spatial orientation
When you turn your head, fluid in the semicircular canals lags behind and moves against tiny sensors in the inner ear. Those sensors tell the brain about the…
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A damaged toenail can keep a record of an injury for months
New nail grows from tissue at its base, gradually pushing the older plate forward. Toenails replace themselves much more slowly than fingernails, so a mark…
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Why swallowing mucus may help your immune system
Mucus traps particles and pathogens in the airways, and some of it is naturally swallowed. Stomach acid breaks down what it carries; fragments can then be…
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Even a lung test depends on how you are positioned
A review of 43 studies found that body position changed measured breathing capacity, often with higher values in more upright positions. The effect varied…
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Optimism reliably increases overall life satisfaction
An optimistic outlook can change how a stressful event is interpreted: it may feel more manageable, rather than like proof that everything will go wrong. That…
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Why people prefer bad news to uncertainty
Not knowing what will happen leaves you unable to plan; even bad news gives you a definite situation to respond to. Once people know the outcome is negative,…
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Waking a sleepwalker won't make their heart stop
In sleepwalking, the brain can send the body into motion without fully bringing awareness online. That’s why a person may look awake yet seem confused when…
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A small anesthesia study found a difference in redheads
In a 2004 experiment, ten naturally red-haired women needed about 19% more desflurane than ten dark-haired women to suppress movement in response to a…
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Step aerobics grew out of a knee-rehab exercise
After a knee injury, instructor Gin Miller practiced stepping up and down as rehabilitation. Putting that simple movement to music helped turn it into a group…
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Right main bronchus provides a dangerously direct pathway
The right main bronchus branches off the windpipe at a wider, more vertical angle than the left. An inhaled object therefore has a straighter, broader route…
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Red blood cells fold to fit into tight vessels
A red blood cell can bend as it enters a vessel narrower than itself, then spring back once it has passed through. That flexibility lets the oxygen-carrying…
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Chocolate is engineered to change state in your mouth
Its fat crystals help it stay firm at ordinary room temperature while melting near body temperature. Tempering encourages a crystal structure that gives a…
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Pancreas sits entirely hidden behind the stomach pouch
Food does not have to touch the pancreas for the gland to help digest it. The pancreas releases enzymes into a duct that empties into the digestive tract,…
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Duodenum forcefully mixes stomach output with enzymes
As stomach contents enter the duodenum, they are still acidic. The duodenum blends them with neutralizing agents and enzymes, changing the mixture before it…
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The diet drink made from horns and hooves
Prolinn turned crushed horns and hooves into a liquid supplement with artificial cherry flavor. Its diet plan cut food so severely that people were…
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Shaving cuts the hair but leaves its factory running
A razor removes the shaft above the skin while the follicle below keeps producing hair. Each follicle cycles through growth, rest, and shedding, which is why…
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How decongestants clear your nose without removing mucus
When blood vessels in the nasal passages widen, the surrounding lining swells and crowds the airway. Decongestants constrict those vessels, shrinking the…
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Gut microbes can respond to a new menu within days
A 2014 study switched participants to diets made entirely from animal or plant foods and observed rapid changes in their gut microbes. Different nutrients…
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Breast milk's immune cells can surge during an infection
Researchers tracked white blood cells in milk and found rapid increases when a mother or infant was ill, followed by a return toward baseline after recovery.…
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