Health
Discover facts about health. Small discoveries that change the way you see familiar things.
Health
Squeezing legs together violently adds limbs back to center
When you squeeze your legs together, muscles on the inner thighs pull each leg toward the body’s midline. You can feel them engage because they’re drawing the…
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Tactile receptors cluster incredibly densely on human lips
Your lips have many touch receptors packed into a small area. Their dense wiring helps you notice fine differences in texture, which is why a tiny change in…
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An exercise habit can spill over into food choices
A study of participants in a physical-activity program found dietary improvement alongside changes such as greater enjoyment of exercise and confidence in…
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Men’s testosterone changes throughout the day
Testosterone tends to peak in the morning, then decline as the day goes on. It’s one reason a hormone reading is a snapshot of both the person and the time on…
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The man who hiccupped for 68 years
Charles Osborne began hiccupping in 1922 after falling while trying to weigh a hog. The spasms continued until 1990, through two marriages and the raising of…
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A belly-button study found thousands of bacterial types
Researchers sampling 60 navels identified more than 2,000 bacterial phylotypes—groups distinguished by genetic sequences. Many were uncommon, while a smaller…
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Your genes may decide whether you're a morning person
Your chronotype—the tendency to feel more alert earlier or later—is partly shaped by genes such as PER1 and PER2, which help regulate the body’s internal…
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Being left handed is just a complex genetic lottery
About 10% of people are left-handed, but there is no single gene that dictates it. Up to 40 genetic regions are involved, making handedness more like a…
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How your body can wake you before the alarm
A regular routine gives the brain’s internal clock a reliable cue for when to prepare for morning. It can start sending wakefulness-related signals about an…
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Why fraternal twins can run in families
Some women inherit a tendency to release more than one egg in a cycle. If two eggs are released and each is fertilized, fraternal twins can result—so the…
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Deep sleep is a stage you enter, not an on-off switch
Non-REM sleep progresses through N1, N2, and deep N3, each with a different pattern of brain activity. N2 includes brief bursts called sleep spindles; N3 has…
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A gene study found that childhood experience changed the story
A 2002 study followed males from childhood and examined MAOA, a gene involved in processing neurotransmitters. Among those who experienced maltreatment,…
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Why female cells shut down one X chromosome
A cell switches off one X chromosome so it does not produce a double dose of many X-linked gene products. Because different cells make the choice…
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Your body has more sphincters than you think
These muscles work like living gates: a sphincter closes a passage, then relaxes when something needs to move through. There are several in the digestive and…
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Infant heads are comically large compared to adult forms
A baby’s head is about a quarter of its body length because the brain grows early, while the rest of the body still has plenty of growing to do. That big head…
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Your arm span is almost your height
For most people, arm span and height are close because the lengths of the limbs and torso tend to grow in related proportions. Da Vinci popularized the…
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Is your forearm as long as your foot
For many people, the distance from the inner elbow to the wrist is roughly the length of the foot. The match is approximate, because body proportions vary,…
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Humans possess unmatched muscular complexity in faces
The inner eyebrows have their own lifting muscles, so a person can raise that small area without lifting the whole brow. It creates a familiar, almost…
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Why your longest dreams come before waking
Your sleep cycles give later dreams more room: an early dream period lasts about 10 minutes, while the final cycle can stretch to an hour. The dream you…
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You probably carry Neanderthal DNA
When humans and Neanderthals had children, some of their DNA passed into later generations. Most people with Eurasian ancestry carry about 1 to 2 percent of…
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Nighttime arousal doesn't require erotic dreams
During sleep, the body can change blood flow and trigger physical arousal automatically, without a sexual dream setting it off. The response can happen…
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The father—not the mother—determines a baby’s genetic sex
An egg contributes an X chromosome, while a sperm contributes either an X or a Y. That means the sperm’s chromosome determines whether the usual combination…
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Inheriting physical traits requires complex algorithms
A recessive trait can show up in a child even when neither parent visibly has it. If both parents carry a version of a gene without expressing the trait, a…
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Vertical human height relies on hundreds of tiny variables
Height isn’t decided by a single genetic switch: more than 700 genetic variations contribute. Each is one small part of a much bigger group effort, which is…
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