It takes about 20 seconds for a red blood cell to circle the whole body.
102
One human hair can support 3 ounces.
191
The average person's skin weighs twice as much as their brain.
131
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
When you are looking at someone you love, your pupils dilate, they do the same when you are looking at someone you hate.
1k
There are glasses which allow a red-green color-blind person to see colors the way everyone else does.
22
Pain occurs when sounds are above 130 db.
124