Did you Know?

Interesting and note-worthy facts about the human body

The Brain

  • Crossing your arms can reduce pain by confusing your brain.
  • People generally read from paper 25% faster than from a computer monitor.
  • Once we reach the age of 35, we will start losing approximately 7,000 brain cells each day—cells that will never be replaced
  • Your brain is about 2% of your total body weight but uses 20% of your all your body's oxygen and calories.
  • The average human dream lasts only two to three seconds and the average person has at least seven dreams a night. People with higher IQs have more dreams.
  • Shoes are now available with a built-in GPS to help locate people with Alzheimer's or other dementia who have wandered away.

Staying Healthy

  • Some dogs can detect early-stage lung cancer in people based solely on their sense of smell.
  • Over 90% of diseases are caused or complicated by stress.
  • Every three minutes a woman is diagnosed with breast cancer somewhere in the world.
  • The electromagnetic fields produced by mobile phones are classified by the International Agency for Research on Cancer as possibly carcinogenic to humans.
  • In some Asian and African countries, 80% of the population depends on traditional medicine for primary health care.
  • The hepatitis B virus is 50 to 100 times more infectious than HIV.
  • Road traffic injuries are the leading cause of death among young people, aged 15–29 years.
  • Tobacco kills up to half of its users.
  • A needle-free, “nanopatch” vaccine delivery system is being developed that could eliminate the need for shots.

Hair & Skin

  • The main purpose of eyebrows is to keep sweat out of the eyes.
  • Female hair grows more slowly than male hair.
  • Humans have about the same number of hair follicles as a chimpanzee has.
  • Hair will fall out faster on a person who is on a crash diet.
  • Eyebrow hair lasts between 3-5 months before it sheds and an eyelash has a lifespan of about 150 days.
  • Every half square inch of the human skin has about 100 sweat glands, 10 hairs, 15 sebaceous glands, and just under a meter of blood vessels.
  • The average adult skin has an area of about 2 square meters and weighs about 2.5 to 4 kilograms. The entire skin system has about 17 kilometers of blood vessels and 72 kilometers of nerves.
  • The skin constantly renews itself every 27 or 28 days for a total of 1,000 new “suits” of skin in an average lifetime.

The Heart & Blood

  • Blood is about 78% water.
  • The human heart weighs less than 454 grams.
  • The longer the ring finger is in males, the less chance they have of having a heart attack.
  • The risk of cardiovascular disease is twice as high in women who snore regularly compared to women who do not snore.
  • Warfarin, used to clot blood and to prevent blood clots from moving, is the most widely used anticoagulant in North America, but it was originally developed as a pesticide against rodents and it is still available for that purpose.
  • People who ride on roller coasters have a higher chance of getting a blood clot in the brain.


  • New anti-malarial drugs were developed from a plant that been used medicinally in China for almost 2000 years.
  • In ancient Egypt, medical institutions were called "Houses of Life."
  • Tibetan anatomists counted a total of 360 bones in an adult human body, while Western medical books say 206, because they considered cartilage, fingernails, and toenails as bones.
  • Mustargen (nitrogen mustard) is a poisonous gas and blistering agent once used in chemical warfare that is also used as a powerful anticancer drug.
  • Botox was discovered in the fat of spoiled pork and was called botulism by the doctor who figured out a medicinal use for it. In the 1960's it was used to correct cross-eyed syndrome.
  • The oldest known disease in the world is leprosy.
  • In the early 19th century some people believed that riding a carousel was good for blood circulation.

Eating & Overeating

  • It takes your food about seven seconds to get from your mouth to your stomach.
  • The human liver performs over 500 functions.
  • Overeating reduces your ability to hear.
  • The CDC reports that more people are overweight than underweight worldwide.
  • Annual flu shots may be less effective for obese people.
  • You will die from a lack of sleep before you will die from a lack of food.


  • Over one third of all child deaths worldwide are linked to malnutrition.
  • Six-year-olds laugh an average of 300 times a day. Adults only laugh 15 to 100 times a day.
  • Babies are born color-blind.
  • Babies' eyes do not produce tears until they are approximately six to eight weeks old.
  • Pneumonia is the leading cause of death in children worldwide– more than AIDS, malaria, and tuberculosis combined.
  • Your brain changes shape during puberty.


  • 10% of all human beings ever born are alive at this very moment.
  • The earliest documented occurrence of a fetus yawning is at eleven weeks after conception.
  • During a normal pregnancy, the average woman's uterus expands up to five hundred times its normal size.
  • 99% of all maternal deaths (death from childbirth) occur in developing countries.
  • Women who smoke take longer to conceive, suffer from infertility at higher rates, and have higher rates of miscarriage.
  • Babies hiccup while still in the womb because the respiratory center of a developing child’s brain works just like that of an adult, even though they are not yet breathing air.


  • Our eyes can distinguish up to one million color surfaces and take in more information than the largest telescope known to man.
  • Half of all cases of deafness and hearing impairment worldwide could be avoided by prevention, early diagnoses, and proper treatment.
  • A scent membrane in a human’s nose is about the size of a postage stamp. A dog’s is about the size of a handkerchief.
  • About 80% of all visual impairments worldwide could be avoided or cured.
  • The eyeball of a human weighs approximately 28 grams.
  • Under the right conditions, the human eye can see candlelight from 22 kilometers away.
  • The eye of a human can distinguish 500 shades of the gray.

Muscles & Bones

  • The only bone not connected to another is the hyoid, found under the chin and at the base of the tongue.
  • The only bone fully grown at birth is located in the ear.
  • The human face is made up of 14 bones.
  • The strongest bone in your body is hollow (the femur).
  • You use up to 200 muscles to take a step.
  • The average person walks the equivalent of twice around the world in a lifetime.


  • Your teeth started to grow as early as six months before you were born.
  • People that suffer from gum disease are twice as likely to have a stroke or heart attack.
  • Smokers are twice as likely to lose teeth as nonsmokers.
  • A pregnant woman's dental health can affect her unborn child.
  • Some brands of toothpaste contain an ingredient found in antifreeze (glycerin or glycerol).