Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
There are times when you're walking that the pressure on your feet exceeds your body weight, and when you're running, it can be three or four times your weight.
62
It takes about 20 seconds for a red blood cell to circle the whole body.
102
The human brain doesn't stop developing until about 25 years old.
102
Your thumb is about the same size as your nose.
124
If you are cold you are more likely to be hungry because you use energy to keep warm.
143
The average person's skin weighs twice as much as their brain.
131