Yawns are more contagious among people with closer relationships.
163
An average heart beats 100,000 times a day, pumping some 2,000 gallons of blood through its chambers. Over a 70-year life span, that adds up to more than 2.5 billion heartbeats.
73
If you are cold you are more likely to be hungry because you use energy to keep warm.
143
Enamel is hardest substance in the human body.
61
Your thumb is about the same size as your nose.
124
Chewing gum boosts your brain power.
285
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