Yawns are more contagious among people with closer relationships.
163
When you take a step, you are using up to 200 muscles.
886
The human brain doesn't stop developing until about 25 years old.
102
Your body is creating and killing about 2.4 million red blood cells per second.
17
It takes about 20 seconds for a red blood cell to circle the whole body.
102
The adult human brain weighs about 3 pounds (1,300-1,400 g).
99
If you are cold you are more likely to be hungry because you use energy to keep warm.
143
If every muscle in your body could pull in one direction, you could lift nearly 25 tons.
22