Goosebumps, blushing, wrinkling, marks, spots, and hair.
Showing 15 oddities.
Skin and hair sit on the surface, wired to nerves and tiny muscles that react to temperature, touch, and emotion. Because the reactions are visible, this region produces some of the most noticeable oddities in the catalogue.
Blushing widens blood vessels in the face when you are embarrassed, and you cannot stop it. Goosebumps pull hair upright using muscles left over from a furrier ancestor. Dermatographia lets a firm stroke raise a red welt
Most of these entries are reflexes you cannot switch off by will. A few, like voluntary piloerection, are the rare exception where someone learns to trigger the reflex on purpose.
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When you are embarrassed, blood vessels in the face open wide and the skin turns red. You cannot stop it. Darwin called it the most human of all expressions, and no other animal is known to blush from embarrassment.
In a few people, a firm stroke on the skin raises a red welt within minutes, clear enough to write words with a fingernail. It is the skin's hive response set on a hair trigger.
Tiny pale yellow or white bumps, 1 to 3 mm across, on the edge of the lips or inside the cheeks. They are ordinary oil glands in a place without hair. Most adults have them.
Tiny muscles at the base of most hairs pull the hair upright when you are cold, scared, or moved. In a furry animal this traps warm air or makes it look bigger. In a human the raised hair does almost nothing.
Fingertips and toes wrinkle after several minutes in water. This is not just the skin soaking up water. It is the nervous system shrinking the fingertip on purpose, and the wrinkles may improve grip when wet.
An extra nipple, usually small and flat, on a line running from the armpit to the groin. Between 1 in 500 and 1 in 18 people have one, and it is often mistaken for a mole.
Giving yourself goosebumps on command, without music, cold, or fear. Nobody knows how many people can do it, but it seems rare. The muscles involved are not supposed to take orders.
These entries belong to another region first, and touch this one too.
A pleasant tingling that starts on the scalp and moves down the neck and spine, set off by whispering, tapping, soft sounds, or gentle personal attention. Not everyone gets it. A large online community is built around it.
Some earlobes hang free and others join the head directly. Textbooks taught this as one gene, but a 2017 study found at least 49 genetic regions involved, and the two shapes blend into each other.
A second row of eyelashes growing from the oil-gland openings along the inner edge of the eyelid. It is rare. It can be inherited or acquired. Elizabeth Taylor was born with it.
Turning the upper eyelid inside out so the pink inner surface shows. Nobody has counted how many people can do it. Eye doctors do it to patients to look for grit.
A wave of chills up the back, sometimes with goosebumps, at a powerful moment in music, a film, or a speech. It is thought to come from the brain's reward system reacting to an expectation being met or broken.
A tiny hole in the skin just in front of the ear, present from birth, that can lead to a tunnel under the skin. It is harmless unless it gets infected.
Lifting a single eyebrow while the other stays down. Informal estimates say 30% to 35% of people can do it without training. No study has measured how many of the rest can learn it.
Two toes joined by skin, most often the second and third, in about 1 in 2,000 to 2,500 babies. The toes usually work normally and many people leave them as they are.