Yawns are more contagious among people with closer relationships.
163
Your thumb is about the same size as your nose.
124
It takes about 20 seconds for a red blood cell to circle the whole body.
102
The average sperm cell swims at 8 inches per hour.
76
The adult human brain weighs about 3 pounds (1,300-1,400 g).
99
The largest cell in the human body is the female egg and the smallest is the male sperm.
682
Staying awake for 17 hours is the same for your body as drinking 2 glasses of wine.
193
The average person's skin weighs twice as much as their brain.
131