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
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
Poor eyesight (myopia) is associated with higher IQ.
232
Staying awake for 17 hours is the same for your body as drinking 2 glasses of wine.
193
If you are cold you are more likely to be hungry because you use energy to keep warm.
143
One human hair can support 3 ounces.
191
The human brain has the capacity to store everything that you experience.
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