Odd truths about the human body
Strange things happening inside you right now.
Do human beings glow in the dark?
Yes, faintly. Human bodies emit a small amount of visible light as a by-product of metabolism. Researchers imaged it with ultra-sensitive cameras in 2009. It is roughly a thousand times weaker than the human eye can detect, so nobody has ever seen it.
Why can't I see the blind spot in my own eye?
Because your brain fills it in. Each eye has a patch of retina with no photoreceptors, where the optic nerve exits. You never notice the gap because your visual system invents plausible content to cover it, using whatever surrounds the hole.
Do babies have more bones than adults?
Yes. A newborn has roughly 275 to 300 bones, while most adults have 206. Nothing goes missing. As a child grows, many small bones and pieces of soft cartilage fuse into single larger bones, so the count drops even as the skeleton gets bigger.
Why do your fingers wrinkle in water?
Because your nervous system is doing it on purpose. Wrinkling is an active response, not skin soaking up water: blood vessels under the fingertips constrict and pull the skin into ridges. A 2013 Newcastle University study found people moved wet marbles faster with wrinkled fingers, like tyre treads channelling water away for grip.
Do astronauts get taller in space?
Yes. NASA reports that crew members grow up to three percent taller during long missions on the International Space Station, about five centimetres for a six-foot person. Without gravity squashing the spine, the discs between the vertebrae expand. Height returns to normal after coming home.
How many times does your heart beat in a day?
About 100,000 times. At a typical resting rate of around 70 beats a minute, that is roughly 100,000 beats a day, 35 million a year, and well over two billion in a lifetime. It never takes a break, and it does the whole job with a muscle about the size of your fist.