Enamel is hardest substance in the human body.
61
The human brain doesn't stop developing until about 25 years old.
102
Quick naps not only improve your alertness, but they also help in decision making, creativity and sensory perception.
149
The adult human brain weighs about 3 pounds (1,300-1,400 g).
99
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
After age 30, the brain begins to lose about 50,000 neurons per day - shrinking the brain .25% each year.
55
The average sperm cell swims at 8 inches per hour.
76