By weight, Bone is five times stronger than steel.
417
Only humans shed emotional tears.
331
The largest cell in the human body is the female egg and the smallest is the male sperm.
682
The oldest stone tools found are dated from 2.7 - 2.9 million years ago. The species that made these tools is unknown.
13
Modern humans first appeared about 200,000 years ago, but record keeping didn't begin until about 6,000 years ago. That means about 97% of human history is lost.
21
Your fingernails grow faster in summer.
744
There are glasses which allow a red-green color-blind person to see colors the way everyone else does.
22
After age 30, the brain shrinks a quarter of a percent (0.25%) in mass each year.
139