Yawns are more contagious among people with closer relationships.
163
Our eyes are always the same size from birth, but our nose and ears never stop growing.
266
It takes twice as long to lose new muscle if you stop working out than it did to gain it.
127
The largest cell in the human body is the female egg and the smallest is the male sperm.
682
Your heart will pump about 212 million liters in its lifetime.
26
The human brain doesn't stop developing until about 25 years old.
102
When you get goosebumps and your hair stands, the hair helps to trap air, making you feel warmer by keeping in your body heat.
46
The adult human brain weighs about 3 pounds (1,300-1,400 g).
99