Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
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
Your thumb is about the same size as your nose.
124
It would take about 1,200,000 mosquitoes to fully drain the average human body of blood.
217
If you are cold you are more likely to be hungry because you use energy to keep warm.
143
Quick naps not only improve your alertness, but they also help in decision making, creativity and sensory perception.
149
Enamel is hardest substance in the human body.
61
Yawns are more contagious among people with closer relationships.
163