If Earth's life was compressed into 1 year, then humans would have been around for only 2 seconds.
15
There are glasses which allow a red-green color-blind person to see colors the way everyone else does.
22
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
On average, there's 100 billion neurons in the human brain.
83
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
After age 30, the brain shrinks a quarter of a percent (0.25%) in mass each year.
139
The human brain uses approximately as much energy as a 10 watt light bulb.
120
Tigers can see 6 times better at night than humans.
305