Nine things your body never told you · Deep Cuts

Your emotional tears aren't the same as onion tears

Crying from emotion carries more protein and stress hormones than the reflex tears you get chopping onions — your body is literally flushing stress chemistry out through your eyes.

You're about a centimetre taller in the morning

Overnight, the soft discs between your vertebrae soak up fluid and decompress. A day on your feet slowly squeezes them flat again — so you actually shrink as the day goes on.

Your wounds heal faster in daylight

Skin-repair cells run on a 24-hour body clock. Cuts you get during the day can close up to twice as fast as ones you get at night.

Pregnancy permanently remodels the brain

Brain scans show grey-matter changes that last at least two years after birth — distinct enough that a computer can tell who has been pregnant from the scan alone.

Identical twins don't have identical fingerprints

Same DNA, different prints. Ridge patterns are sculpted by random pressure and movement in the womb, so even genetic clones end up unique at the fingertips.

Late in life, Monet started seeing ultraviolet

Cataract surgery removed the lens that normally filters out UV light. Afterwards he could perceive bluer, near-ultraviolet tones — and his water lilies shifted toward violet.

Goosebumps are a leftover reflex for fur you no longer have

Tiny muscles yank your hairs upright — once useful for fluffing a coat to trap heat or look bigger to a threat. You kept the wiring long after you lost the fur.

Brain freeze is your brain protecting itself

Hit the roof of your mouth with cold and nearby blood vessels rapidly clench, then flood. The ache is referred pain — a built-in alarm telling you to slow down and guard the blood supply to your brain.

Yawning is contagious — maybe even right now

Just reading about yawning can set one off. It's tied to empathy: the more socially bonded you are to someone, the more catching their yawn becomes.