Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Poor eyesight (myopia) is associated with higher IQ.
232
It takes about 20 seconds for a red blood cell to circle the whole body.
102
Enamel is hardest substance in the human body.
61
Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118
If your DNA was stretched out it would reach to the moon 6,000 times.
256
Our eyes are always the same size from birth, but our nose and ears never stop growing.
269