Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
The average sperm cell swims at 8 inches per hour.
76
The human brain uses approximately as much energy as a 10 watt light bulb.
120
Staying awake for 17 hours is the same for your body as drinking 2 glasses of wine.
193
Dogs can be trained to identify the scent of lung cancer long before symptoms develop.
190
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
It takes about 20 seconds for a red blood cell to circle the whole body.
102
After age 30, the brain begins to lose about 50,000 neurons per day - shrinking the brain .25% each year.
55