Enamel is hardest substance in the human body.
61
Yawns are more contagious among people with closer relationships.
163
If your DNA was stretched out it would reach to the moon 6,000 times.
256
It takes twice as long to lose new muscle if you stop working out than it did to gain it.
127
The adult human brain weighs about 3 pounds (1,300-1,400 g).
99
The average sperm cell swims at 8 inches per hour.
76
One human hair can support 3 ounces.
191
The human brain doesn't stop developing until about 25 years old.
102