For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
The human brain is very soft, having a consistency similar to soft gelatin or firm tofu.
13
The average sperm cell swims at 8 inches per hour.
76
Your body is creating and killing about 2.4 million red blood cells per second.
17
The average person's skin weighs twice as much as their brain.
131
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Staying awake for 17 hours is the same for your body as drinking 2 glasses of wine.
193