The average sperm cell swims at 8 inches per hour.
4
Tigers can see 6 times better at night than humans.
305
The human brain doesn't stop developing until about 25 years old.
102
Enamel is hardest substance in the human body.
61
Most of us have microscopic, worm like mites named Demodex that live in our eyelashes and have claws and a mouth.
-137
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
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
Only humans shed emotional tears.
331