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
Every human spent about half an hour as a single cell.
144
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
There are times when you're walking that the pressure on your feet exceeds your body weight, and when you're running, it can be three or four times your weight.
62
Having sex can make a woman look younger and more attractive due to the release of estrogen and collagen.
346
It took 200,000 years for humans to reach 3 billion in number. It took 40 years for the next 3 billion.
11
One human hair can support 3 ounces.
191