Community discoveries

Human body

Every discovery began with someone wanting to know a little more.

7 discoveries

Purkinje classified fingerprints in 1823, decades before they were used as evidence.

Johannes Evangelista Purkinje published a thesis in 1823 describing nine fingerprint pattern types, the first scientific classification. Police didn't adopt fingerprints for identification until the 1890s.

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Human body2 min read

Pruned fingers after a bath are caused by nerves, not water absorption

Water doesn't swell the skin; it triggers autonomic nerves that constrict blood vessels in the fingertip, shrinking the tissue beneath and pulling the skin into wrinkles.

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Human body2 min read

Your brain fills in the eye's blind spot, so you never see a hole.

Each eye has a blind spot where the optic nerve leaves the retina, but the brain fills it in using surrounding visual information, so we never notice a gap.

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Human body2 min read

Fingerprints form before birth and regrow in the same pattern after severe burns

Fingerprint ridges develop on the fetus around the 17th week of pregnancy and remain unchanged for life. If a burn spares the basal skin layer, the ridges regrow in the original pattern.

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Human body2 min read

Your stomach lining replaces itself every 3–5 days to avoid digesting itself

Stomach cells secrete a thick mucus barrier and are shed and rebuilt every few days. This rapid turnover keeps acid and pepsin from eating through the stomach wall.

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Human body2 min read

The human spleen stores red blood cells and platelets, releasing them during exercise or stress.

The spleen's venous sinuses hold a reserve of red blood cells and platelets. During exercise or stress, signals trigger contraction that releases these cells into circulation.

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Human body2 min read

Human embryos briefly grow a tail that is normally absorbed before birth

All human embryos develop a tail bud around the fourth week, then the tail regresses and its vertebrae fuse into the coccyx. Rarely, a baby is born with a soft tail that has no bones.

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