The human brain doesn't stop developing until about 25 years old.
102
It takes about 20 seconds for a red blood cell to circle the whole body.
102
Our eyes are always the same size from birth, but our nose and ears never stop growing.
266
Yawns are more contagious among people with closer relationships.
163
Enamel is hardest substance in the human body.
61
One human hair can support 3 ounces.
191
The adult human brain weighs about 3 pounds (1,300-1,400 g).
99
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