Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
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
Every year your body replaces 98% of your atoms.
119
Our eyes are always the same size from birth, but our nose and ears never stop growing.
266
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
Yawns are more contagious among people with closer relationships.
163
The human brain is very soft, having a consistency similar to soft gelatin or firm tofu.
13