Enamel is hardest substance in the human body.
61
Yawns are more contagious among people with closer relationships.
163
It takes twice as long to lose new muscle if you stop working out than it did to gain it.
127
The human brain uses approximately as much energy as a 10 watt light bulb.
120
Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
If you are cold you are more likely to be hungry because you use energy to keep warm.
143
The adult human brain weighs about 3 pounds (1,300-1,400 g).
99