Only humans shed emotional tears.
331
Stress can result in more headaches as a result of the body rerouting blood flow to other parts of the body.
92
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
It takes about 20 seconds for a red blood cell to circle the whole body.
102
Humans are capable of running 40 mph according to a study by bio-mechanical expert Dr. Matthew Bundle. Today's fastest man, Usain Bolt, has a top speed of 28 mph.
34
It takes twice as long to lose new muscle if you stop working out than it did to gain it.
127
The world's shortest man measures only 21.5 inches.
73
A third of the human population sneezes when they look at the Sun. Light can signal the ocular nerve near the sinuses and triggers a sneeze.
18