Yawns are more contagious among people with closer relationships.
163
The human brain doesn't stop developing until about 25 years old.
102
The human brain is very soft, having a consistency similar to soft gelatin or firm tofu.
13
Your heart will pump about 212 million liters in its lifetime.
26
Your body is creating and killing about 2.4 million red blood cells per second.
17
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
The average person's skin weighs twice as much as their brain.
131
The average sperm cell swims at 8 inches per hour.
76