Crying literally alleviates stress and uniquely allows humans to decrease feelings of anger and sadness.
24
A person will create enough saliva to fill two average size swimming pools during his lifetime.
191
Tigers can see 6 times better at night than humans.
305
Stress can result in more headaches as a result of the body rerouting blood flow to other parts of the body.
92
It takes about 20 seconds for a red blood cell to circle the whole body.
102
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