Yawns are more contagious among people with closer relationships.
163
Our eyes are always the same size from birth, but our nose and ears never stop growing.
266
It takes about 20 seconds for a red blood cell to circle the whole body.
102
When you take a step, you are using up to 200 muscles.
886
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
The human brain doesn't stop developing until about 25 years old.
102
It takes twice as long to lose new muscle if you stop working out than it did to gain it.
127
The human brain is very soft, having a consistency similar to soft gelatin or firm tofu.
13