1. It takes 17 muscles to smile and 43 muscles to frown.
2. Six-year-olds laugh an average of 300 times a day. Adults laugh only 15 to 100 times a day. Laughing lowers levels of stress hormones and strengthens the immune system.
3. The strongest muscle in the body is the tongue, and every tongue has a unique print.
4. The average human produces 25,000 quarts (23,650 L) of saliva in a lifetime, enough to fill two swimming pools.
5. You blink over 10,000,000 times a year.
6. The average person falls asleep in 7 minutes.
7. Left-handed people make up about 10 percent of the world’s population.
8. Enamel, found in your teeth, is the hardest material in your body.
9. The largest human organ in the skin, with a surface area of about 25 square feet (2.25 square meters).
10. The gluteus maximus or buttocks muscle is the largest muscle in your body.
11. Every second, five people are born and two people die.
12. Every minute, 300 million cells die in the human body.
13. The brain consumes about one-fifth of all the calories we take in. It burns more energy than any other organ of the body. Therefore, the “brain power” used in mathematical or linguistic problem-solving can be as effective for losing weight as aerobic exercise.
14. Your heart pumps 3,600 gallons (13,623 L) of blood in one day.
15. It takes about 20 seconds for a red blood cell to circulate through the whole body.
16. It takes about 6 months for a toenail, and 3 months for a fingernail, to grow from the base to the tip.
17. An average human scalp has 100,000 hairs.
18. When you’re born you have 300 bones, but by adulthood you have only 206.
19. The vocabulary of the average person consists of 5,000 to 6,000 words.
20. Women burn about 50 fewer calories of fat than men do each day.