Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
When you get goosebumps and your hair stands, the hair helps to trap air, making you feel warmer by keeping in your body heat.
46
The human brain uses approximately as much energy as a 10 watt light bulb.
120
Dogs can be trained to identify the scent of lung cancer long before symptoms develop.
190
The human body contains over a billion miles of DNA.
147
The human brain doesn't stop developing until about 25 years old.
102