Enamel is hardest substance in the human body.
61
Yawns are more contagious among people with closer relationships.
163
The average sperm cell swims at 8 inches per hour.
76
The human body contains over a billion miles of DNA.
147
Most of us have microscopic, worm like mites named Demodex that live in our eyelashes and have claws and a mouth.
-137
The human brain doesn't stop developing until about 25 years old.
102
The average person's skin weighs twice as much as their brain.
131
It takes twice as long to lose new muscle if you stop working out than it did to gain it.
127