Know Your Body: Hair

We tear it out, we urge others to keep it on, and more often than advised, we let it down. It’s called hair and we’re blimmin’ covered in it.

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Hair We Go
Hair is one of the defining characteristics of mammals. On the human scalp alone, the average number of hairs is 120,000 (natural blondes tend to have more, redheads less). It’s the second fastest growing tissue in the body (bone marrow is the fastest) and a full head of the stuff gathered together like a creepy follicular rope can support an incredible 23 tonnes of weight.

Hair We Go Again
Hair is made up of keratin—which can also be found on the outer layer of our skin and nails—and all the hair you can actually see on the surface is dead. It can grow/die just about anywhere on the body, except for the palms of your hands, the soles of your feet and on your lips, eyelids and mucous membranes.

Right Hair, Right Now
Hair is 50 percent carbon, 21 percent oxygen, 17 percent nitrogen, 6 percent hydrogen, and 5 percent sulphur. It’s often used by white-coated forensic types to reveal what’s present in a person’s bloodstream, from medicine, drugs and alcohol to vitamins and minerals.

Hair Today, Gone Tomorrow
On average, human hair grows 0.3 to 0.5 millimetres per day, 1.25 centimetres per month and 15 centimetres (or 6 inches) per year. Depending on the size of your neck/back, it usually takes about three years to grow it to your shoulders and seven years to grow it to your waist. Apparently, warm climates and a regular sex life encourage it to grow quicker (so avoid these unless you want a costly barber bill).