It takes about 20 seconds for a red blood cell to circle the whole body.
102
The average sperm cell swims at 8 inches per hour.
4
The average person's skin weighs twice as much as their brain.
131
Only 12,000 years ago there was a species closely related to modern humans called Homo floresiensis that had been living on an Indonesian Island. They used fire and rather advanced tools, yet were only about 3 feet tall and weighed around 25kg.
15
Our eyes are always the same size from birth, but our nose and ears never stop growing.
266
A human brain produces as many as 12,000 to 50,000 thoughts per day, depending on how deep a thinker a person is.
23
Tigers can see 6 times better at night than humans.
305