Enamel is hardest substance in the human body.
61
The average sperm cell swims at 8 inches per hour.
76
Yawns are more contagious among people with closer relationships.
163
Staying awake for 17 hours is the same for your body as drinking 2 glasses of wine.
193
The human brain doesn't stop developing until about 25 years old.
102
Every year your body replaces 98% of your atoms.
119
If every muscle in your body could pull in one direction, you could lift nearly 25 tons.
22