It took 200,000 years for humans to reach 3 billion in number. It took 40 years for the next 3 billion.
11
Having sex can make a woman look younger and more attractive due to the release of estrogen and collagen.
346
The human brain is very soft, having a consistency similar to soft gelatin or firm tofu.
13
An average heart beats 100,000 times a day, pumping some 2,000 gallons of blood through its chambers. Over a 70-year life span, that adds up to more than 2.5 billion heartbeats.
73
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
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
Only humans shed emotional tears.
331
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515