Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Your thumb is about the same size as your nose.
124
Staying awake for 17 hours is the same for your body as drinking 2 glasses of wine.
193
Our eyes are always the same size from birth, but our nose and ears never stop growing.
266
Enamel is hardest substance in the human body.
61
If you are cold you are more likely to be hungry because you use energy to keep warm.
143
Every year your body replaces 98% of your atoms.
119
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