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100 Amazing Things You Never Knew About Your Body

You think you’re learning everything you can in your biology and anthropology classes, but textbook editors simply don’t have all the space they need to give you the full story of your body. Some of the facts below are trivial, some are ancient history, and some of them may very well save your life one day. So read up, and enjoy this wild and whacky anatomical analysis.
Unusual Facts
You’ll probably wonder why you never heard these cool facts in biology class before. From hangover cures to exploding head syndrome, these tidbits are must-knows.
  1. Every person has a unique tongue print:…just like our fingers!
  2. Eating fruits and vegetables may help the human body make its own aspirin: People who intake benzoic acid, a natural substance in fruits and vegetables, make their own salicylic acid, the key component that gives aspirin its anti-inflammatory and pain-relieving properties.
  3. Baking soda can whiten teeth, garlic can help treat athlete’s foot, and honey can soothe a hangover.
  4. Facebook may be good for your health: Studies show that staying in touch with family and friends can ward off memory loss and help you live longer.
  5. Exploding head syndrome is real (but rare): The American Sleep Association explains that a person with exploding head syndrome experiences a loud, indecipherable noise that seems to originate from inside the head.
  6. Regular exercise can lower a woman’s cancer risk, but only if she’s getting enough sleep: Check out the link to see what the National Cancer Institute has to say about this important fact.
  7. Body position affects memory: Memories are highly embodied in our senses. A scent or sound may evoke a distant episode from one’s childhood. The connections can be obvious (a bicycle bell makes you remember your old paper route) or inscrutable.
  8. Your bones can self-destruct: In addition to supporting the bag of organs and muscles that is our body, bones help regulate our calcium levels. If the element is in short supply, certain hormones will cause bones to break down, upping calcium levels in the body until the appropriate extracellular concentration is reached.
  9. Your brain has a huge appetite: Though it makes up only 2 percent of our total body weight, the brain demands 20 percent of the body’s oxygen and calories.
  10. Puberty reshapes the brain: Why is adolescence so emotionally unpleasant? Hormones like testosterone actually influence the development of neurons in the brain, and the changes made to brain structure have many behavioral consequences. Expect emotional awkwardness, apathy and poor decision-making skills as regions in the frontal cortex mature.
All About…Weight
Here are some great facts you should definitely know about how your body metabolizes and stores fat.
  1. Weight really is genetic: But, a genetic predisposition isn’t necessarily a life sentence, experts say. Exercising regularly can offset the risk of obesity.
  2. Some people just have more fat cells: While you can’t reduce your total number of fat cells, there are things you can do to keep them small. (See next point.)
  3. You can change your metabolism: Gaining as little as 11 pounds can slow metabolism and send you spiraling into a vicious cycle: As you gain more fat, it becomes harder to lose it. But, scientists say physical activity can raise your metabolism back up to fat-blasting levels.
  4. Stress fattens you up: The most direct route is the food-in-mouth syndrome: Stressful circumstances (your bank account, your boss) spark cravings for carbohydrate-rich snack foods, which in turn calm stress hormones.
  5. Your mom’s pregnancy sealed your fate: Science says sugary and fatty foods, consumed even before you’re born, can wreak havoc on your future relationship  with fat.
  6. Sleep more, lose more: University of Chicago researchers reported that sleep deprivation upsets our hormone balance, triggering both a decrease in leptin (which helps you feel full) and an increase of ghrelin (which triggers hunger).
  7. Your spouse’s weight matters: Research shows that weight gain and loss can be, well, contagious. A study in the New England Journal of Medicine suggests that if one spouse is obese, the other is 37 percent more likely to become obese too. The researchers concluded that obesity seems to spread through social networks.
  8. A virus can cause obesity: Adenoviruses are responsible for a host of ills, from upper respiratory tract problems to gastrointestinal troubles. It also seems to increase the number of fat cells in the body as well as the fat content of these cells.
  9. Cookies really are addictive: When subjects at Monell Chemical Senses Center in Philadelphia were shown the names of foods they liked, the parts of the brain that got excited were the same parts activated in drug addicts.
  10. Pick a diet, any diet: What really matters is your ability to moderate your intake of food. Feel free to use your favorite full-fat salad dressing, but your lettuce shouldn’t be swimming in it. You can cut carbs, fats, or just calories in general.
All About…Your Heart
It’s a sad fact that heart disease is the number one killer in the United States; what most people don’t realize is how preventable it is. Learn these facts, then do your part to protect your heart.
  1. Laughter is therapeutic: Watching a funny movie for even 15 minutes can increase your blood flow. Remember to laugh every day—it can keep your heart happy and healthy.
  2. Chest pain isn’t the only sign of a heart attack: Symptoms for most heart attacks include mild chest pain, some shoulder discomfort, or shortness of breath. Other signs can be nausea, lightheadedness, or breaking out in a cold sweat
  3. If you’re over 20, you should know your cholesterol level: If it’s high, there are treatments (including medication and exercises) that can help. You should also get your blood pressure and your blood sugar levels checked regularly.
  4. Obesity often leads to type 2 diabetes: Research has shown that eating more fruits, vegetables, and fiber can actually change the blood’s sensitivity to insulin within as little as two weeks.
  5. Walking can save your life: A recent study found that a sedentary 40-year-old woman who begins walking briskly half an hour a day, four days a week, can enjoy almost the same low risk of heart attack as a woman who has exercised regularly her entire life.
  6. Children can suffer from hypertension, too: About five out of every 100 children have higher than normal blood pressure.
You Have Super Powers!
Believe it or not, we’ve all got a little Clark Kent in us somewhere!
  1. Super strength: Your fight-or-flight capacities point toward fighting, you can do the things you’ve heard of in the news, like lift cars off of your loved ones or push 600-pound boulders out of your way.
  2. Supersonic hearing: Echolocation–it’s the way people with visual impairment continue to do amazing things. A prime example of this hidden sensory super power is Daniel Kish, a mountain biker who has been completely blind his whole life. He bikes better and faster than most people with vision, all by using sound to mentally paint a picture of the world around him. He does it so fast he can avoid trees, boulders and bears while speeding down the side of a mountain.
  3. Super memory: Your brain technically has the ability to store every single thing you’ve ever seen or heard or experienced.
  4. Super pain threshold: In moments of shock and trauma, your brain flips off pain like a switch. Ask somebody like Amy Racina, who fell off a cliff, landing six stories below, shattering her knee and breaking her hip. Not feeling more than minor pain, even with broken bone jutting out from her skin, she dragged herself until she found help. It was only at the point when she was being loaded safely into a helicopter that the pain returned.
  5. Time manipulation: How fast time moves for you is literally all in your head. Experts say it’s because your brain has two modes of experiencing the world, rational and experiential. Read more about these modes and how they could save your life.
All About…Skin
These fantastic (but not-so-appetizing) facts will have you thinking twice every time you look in the mirror.
  1. Weight game: An average adult’s skin spans 21 square feet, weighs nine pounds, and contains more than 11 miles of blood vessels.
  2. Sweating like a…human: The skin releases as much as three gallons of sweat a day in hot weather. The areas that don’t sweat are the nail bed, the margins of the lips, the tip of the penis, and the eardrums.
  3. Take a bath: Body odor comes from a second kind of sweat— a fatty secretion produced by the apocrine sweat glands. The odor is caused by bacteria on the skin eating and digesting those fatty compounds.
  4. The perfect crime: Some people never develop fingerprints at all. Two rare genetic defects, known as Naegeli syndrome and dermatopathia pigmentosa reticularis, can leave carriers without any identifying ridges on their skin.
  5. Hold your breath: Globally, dead skin accounts for about a billion tons of dust in the atmosphere. Your skin sheds 50,000 cells every minute.
  6. It can see: In blind people, the brain’s visual cortex is rewired to respond to stimuli received through touch and hearing, so they literally "see" the world by touch and sound.
  7. Master race, my melanin!: White skin appeared just 20,000 to 50,000 years ago, as dark-skinned humans migrated to colder climes and lost much of their melanin pigment.
  8. You see very, very white people: Albinos are often cast as movie villains, as seen in The Da Vinci Code, Die Another Day, The Matrix Reloaded, and—inexplicably—the 2001 flick Josie and the Pussycats. Robert Lima of Penn State suggests that people associate pale-skinned albinos with vampires and other mythical creatures of the night.
  9. Who needs keys?: More than 2,000 people have radio frequency identification chips, or RFID tags, inserted under their skin. The tags can provide access to medical information, log on to computers, or unlock car doors.
  10. You’re reading what?!: The Cleveland Public Library, Harvard Law School, and Brown University all have books clad in skin stripped from executed criminals or from the poor.
All About…Hygiene
Throughout history, humans have evolved to become cleaner, healthier, and fresher-smelling beings, but we’re certainly not sterile. These somewhat-disturbing (but very interesting) hygenic truths might have you showering more often than ever before.
  1. We’re really dirty: The human body is home to some 1,000 species of bacteria. There are more germs on your body than people in the United States.
  2. Be careful what you wash with: Antibacterial soap is no more effective at preventing infection than regular soap, and triclosan (the active ingredient) can mess with your sex hormones.
  3. Pee like an Egyptian: Ancient Egyptians and Aztecs rubbed urine on their skin to treat cuts and burns. Urea, a key chemical in urine, is known to kill fungi and bacteria.
  4. You might want to skip the fountain drink: There are more bacteria in ice machines at fast-food restaurants than in toilet bowl water.
  5. Floor food isn’t good: There’s no “five-second rule” when it comes to dropping food on the ground. Bacteria need no time at all to contaminate food.
  6. TV can kill: TV remotes spread antibiotic-resistant Staphylococcus, which contributes to the 90,000 annual deaths from infection acquired in hospitals.
  7. Make sure your doctor washes his hands: It is now believed President James Garfield died not from the bullet fired by Charles Guiteau but because the medical team treated the president with manure-stained hands, causing a severe infection that killed him three months later.
  8. Mount Soapo: Soap gets its name from the mythological Mount Sapo. Fat and wood ash from animal sacrifices there washed into the Tiber River, creating a rudimentary cleaning agent that aided women doing their washing.
  9. Sorry, Mom: Up to a quarter of all women giving birth in European and American hospitals in the 17th through 19th centuries died of puerperal fever, an infection spread by unhygienic nurses and doctors.
  10. Don’t forget to floss: The first true toothbrush, consisting of Siberian pig hair bristles wired into carved cattle-bone handles, was invented in China in 1498. But tooth brushing didn’t become routine in the United States until it was enforced on soldiers during World War II.
All About…Sex and Gender
Click on these links, and you’ll get a whole new take on gender, sexuality, and the complexity of human relationships.
  1. What were they waiting for?: Life emerged on earth about 3.8 billion years ago, but sex did not evolve until more than 2 billion years later.
  2. Why does it take two?: Scientists are not sure, since asexual reproduction is a better evolutionary strategy in some important ways.
  3. Better for your liver than tylenol: Sex cures headaches. Endorphins released into our bloodstream when we have sex not only give us pleasure but also act as painkillers.
  4. Coo-coo for cocoa: 70% of women would rather eat choclate than have sex.
  5. Staying alive: Sex wards off heart attacks. Frequent sexual intercourse (twice or more per week) lowers your chance of a fatal heart attack.
  6. It’s actually a cure-all: It also decreases pain from menstrual cramps and arthritis. It increases levels of endorphins and corticosteroids, raising pain thresholds.
  7. Calm yourself: Sex reduces stress, so try to make time for it at least a few times a week.
  8. What’s love got to do with it?: Sexual arousal and romantic love activate quite distinct areas of the brain—and love is clearly the more powerful. The latter turns on dopamine-rich regions linked with motivation, and falling in love is not unlike the rush of taking cocaine, hence the addictiveness of a new crush, and the withdrawal-like symptoms of love lost.
  9. Curious?: Recent research suggests women may be “intrinsically bisexual,” and the higher their libido, the more they desire both sexes.
  10. Asexuality 101: One percent of adults have zero interest in sex and have never felt sexually attracted to anyone at all.
All About…Mental Health
Mental health and sickness is a big part of being human. Though it’s been looked at and discussed with ridicule in previous generations, today’s world should know these important facts about human psychology and psychiatry.
  1. Mental illness is more common than you think: The National Institute of Mental Health reports that One in four adults-approximately 57.7 million Americans-experience a mental health disorder in a given year.
  2. Adults aren’t the only ones who suffer: The U.S. Surgeon General reports that 10 percent of children and adolescents in the United States suffer from serious emotional and mental disorders that cause significant functional impairment in their day-to-day lives at home, in school and with peers.
  3. Mental illness strikes young: Mental illness usually strike individuals in the prime of their lives, often during adolescence and young adulthood. All ages are susceptible, but the young and the old are especially vulnerable.
  4. It’s expensive: The economic cost of untreated mental illness is more than 100 billion dollars each year in the United States.
  5. It’s treatable: Most people who live with serious mental illnesses can significantly reduce the impact of their illness and find a satisfying measure of achievement and independence.
  6. Act fast: Early identification is of vital importance to treatment.
  7. Don’t be bullied: Stigma erodes confidence that mental disorders are real, treatable health conditions.
  8. Bipolar disorder is blind to gender: Over 10 million people in America have bipolar disorder, and the illness affects men and women equally.
  9. Suicide is serious: Each year in the U.S., approximately 2 million U.S. adolescents attempt suicide, and almost 700,000 receive medical attention for their attempt.
  10. Seasonal Affective Disorder (SAD) might be genetic: Many people with SAD report at least one close relative with a psychiatric condition, most frequently a severe depressive disorder (55 percent) or alcohol abuse (34 percent).
All About…Working Out
You already know how essential physical fitness is, and how important it is to take care of your body. But we’re willing to bet you didn’t know all of these bits of information about how to work out in a way that benefits you best.
  1. Incline builds muscle: Get off the flats and into the hills. Walking uphill makes you stronger.
  2. Treat your feet: Each step puts up to 1.5 times your body weight on your feet, which are shock absorbers that bear 60 tons of pressure every mile you travel.
  3. Lub-dub: The more fit you are, the harder it is to reach your target heart rate.
  4. Work it, girl: A 145-pound woman walking briskly (4 mph) burns 82 calories every 15 minutes.
  5. Getting back in: If you’ve taken off more than one month from exercising, give yourself at least four weeks to regain endurance and strength. Start slow, and increase your time, distance and intensity gradually, even if you were previously well-trained.
  6. Caffeine won’t kill: Despite popular thinking, caffeine doesn’t cause dehydration during exercise. In fact, the caffeine in a cup of tea or coffee improves speed and endurance.
  7. Change it up: Running on a circular track puts stress on the outside of your foot. Alternate the direction you run every other day or every five laps.
  8. Tums, anyone?: Strenuous exercise can cause acid reflux in healthy, conditioned athletes.
  9. Go shopping: Keep the spring in your step. Replace your running shoes every 300 to 400 miles.
  10. You’re not a camel: If you’re dehydrated even 5%, your metabolism can fall 20% to 30%. You’ll fire more easily and be irritable.
All about…Preventing Cancer
Cancer is the number two killer of people in the United States, but it doesn’t have to put you in the ground, too. Follow these healthy tips to treat your body to a longer, healthier life.
  1. Serve sauerkraut at your next picnic: The fermentation process involved in making sauerkraut produces several other cancer-fighting compounds, including ITCs, indoles, and sulforaphane. To reduce the sodium content, rinse canned or jarred sauerkraut before eating.
  2. Eat your fill of broccoli, but steam it rather than microwaving it: Broccoli is a cancer-preventing superfood, one you should eat frequently. But microwaving broccoli destroys 97 percent of the vegetable’s cancer-protective flavonoids.
  3. Toast some Brazil nuts and sprinkle over your salad: They’re a rich form of selenium, a trace mineral that convinces cancer cells to commit suicide and helps cells repair their DNA.
  4. Add garlic to everything you eat: Garlic contains sulfur compounds that may stimulate the immune system’s natural defenses against cancer, and may have the potential to reduce tumor growth. Studies suggest that garlic can reduce the incidence of stomach cancer by as much as a factor of 12!
  5. Eat cantaloupe: Cantaloupe is a great source of carotenoids, plant chemicals shown to significantly reduce the risk of lung cancer.
  6. Drink water: The amount of water women drink correlates to their risk of colon cancer, with heavy water drinkers reducing their risk up to 45 percent.
  7. Get about 15 minutes of sunlight each day: Getting too little vitamin D may increase your risk of multiple cancers, including breast, colon, prostate, ovarian, and stomach, as well as osteoporosis, diabetes, multiple sclerosis, and high blood pressure.
  8. Sprinkle scallions over your salad: A diet high in onions may reduce the risk of prostate cancer 50 percent. But the effects are strongest when they’re eaten raw or lightly cooked.
  9. Make a batch of fresh lemonade or limeade: A daily dose of citrus fruits may cut the risk of mouth, throat, and stomach cancers by half, Australian researchers found.
  10. Take advantage of your friends and family (they won’t mind): Men with high levels of stress and those with less satisfying contacts with friends and family members had higher levels of prostate-specific antigen (PSA) in their blood, a marker for the development of prostate cancer.
Weird Parts We Don’t Need
Evolution has gotten us pretty far, from our apelike ancestors to the upright walking, talking, complex thinking creatures we are today. But along the way, it left behind some traces of our previous forms, like extrinsic ear muscles and tail bones.
  1. Vomeronasal organ: A tiny pit on each side of the septum is lined with nonfunctioning chemoreceptors. They may be all that remains of a once extensive pheromone-detecting ability.
  2. Wisdom teeth: Early humans had to chew a lot of plants to get enough calories to survive, making another row of molars helpful. Only about 5 percent of the population has a healthy set of these third molars.
  3. Third eyelid: A common ancestor of birds and mammals may have had a membrane for protecting the eye and sweeping out debris. Humans retain only a tiny fold in the inner corner of the eye.
  4. Male Nipples: Lactiferous ducts form well before testosterone causes sex differentiation in a fetus. Men have mammary tissue that can be stimulated to produce milk.
  5. Body hair: Brows help keep sweat from the eyes, and male facial hair may play a role in sexual selection, but apparently most of the hair left on the human body serves no function.
  6. Female vas deferens: What might become sperm ducts in males become the epoophoron in females, a cluster of useless dead-end tubules near the ovaries.
  7. Fifth toe: Lesser apes use all their toes for grasping or clinging to branches. Humans need mainly the big toe for balance while walking upright.
  8. Coccyx: These fused vertebrae are all that’s left of the tail that most mammals still use for balance and communication. Our hominid ancestors lost the need for a tail before they began walking upright.
  9. Thirteenth Rib: Our closest cousins, chimpanzees and gorillas, have an extra set of ribs. Most of us have 12, but 8 percent of adults have the extras.
  10. Extrinsic ear muscles: This trio of muscles most likely made it possible for prehominids to move their ears independently of their heads, as rabbits and dogs do. We still have them, which is why most people can learn to wiggle their ears.
You think you’re learning everything you can in your biology and anthropology classes, but textbook editors simply don’t have all the space they need to give you the full story of your body. Some of the facts below are trivial, some are ancient history, and some of them may very well save your life one day. So read up, and enjoy this wild and whacky anatomical analysis.
Unusual Facts
You’ll probably wonder why you never heard these cool facts in biology class before. From hangover cures to exploding head syndrome, these tidbits are must-knows.
  1. Every person has a unique tongue print:…just like our fingers!
  2. Eating fruits and vegetables may help the human body make its own aspirin: People who intake benzoic acid, a natural substance in fruits and vegetables, make their own salicylic acid, the key component that gives aspirin its anti-inflammatory and pain-relieving properties.
  3. Baking soda can whiten teeth, garlic can help treat athlete’s foot, and honey can soothe a hangover.
  4. Facebook may be good for your health: Studies show that staying in touch with family and friends can ward off memory loss and help you live longer.
  5. Exploding head syndrome is real (but rare): The American Sleep Association explains that a person with exploding head syndrome experiences a loud, indecipherable noise that seems to originate from inside the head.
  6. Regular exercise can lower a woman’s cancer risk, but only if she’s getting enough sleep: Check out the link to see what the National Cancer Institute has to say about this important fact.
  7. Body position affects memory: Memories are highly embodied in our senses. A scent or sound may evoke a distant episode from one’s childhood. The connections can be obvious (a bicycle bell makes you remember your old paper route) or inscrutable.
  8. Your bones can self-destruct: In addition to supporting the bag of organs and muscles that is our body, bones help regulate our calcium levels. If the element is in short supply, certain hormones will cause bones to break down, upping calcium levels in the body until the appropriate extracellular concentration is reached.
  9. Your brain has a huge appetite: Though it makes up only 2 percent of our total body weight, the brain demands 20 percent of the body’s oxygen and calories.
  10. Puberty reshapes the brain: Why is adolescence so emotionally unpleasant? Hormones like testosterone actually influence the development of neurons in the brain, and the changes made to brain structure have many behavioral consequences. Expect emotional awkwardness, apathy and poor decision-making skills as regions in the frontal cortex mature.
All About…Weight
Here are some great facts you should definitely know about how your body metabolizes and stores fat.
  1. Weight really is genetic: But, a genetic predisposition isn’t necessarily a life sentence, experts say. Exercising regularly can offset the risk of obesity.
  2. Some people just have more fat cells: While you can’t reduce your total number of fat cells, there are things you can do to keep them small. (See next point.)
  3. You can change your metabolism: Gaining as little as 11 pounds can slow metabolism and send you spiraling into a vicious cycle: As you gain more fat, it becomes harder to lose it. But, scientists say physical activity can raise your metabolism back up to fat-blasting levels.
  4. Stress fattens you up: The most direct route is the food-in-mouth syndrome: Stressful circumstances (your bank account, your boss) spark cravings for carbohydrate-rich snack foods, which in turn calm stress hormones.
  5. Your mom’s pregnancy sealed your fate: Science says sugary and fatty foods, consumed even before you’re born, can wreak havoc on your future relationship  with fat.
  6. Sleep more, lose more: University of Chicago researchers reported that sleep deprivation upsets our hormone balance, triggering both a decrease in leptin (which helps you feel full) and an increase of ghrelin (which triggers hunger).
  7. Your spouse’s weight matters: Research shows that weight gain and loss can be, well, contagious. A study in the New England Journal of Medicine suggests that if one spouse is obese, the other is 37 percent more likely to become obese too. The researchers concluded that obesity seems to spread through social networks.
  8. A virus can cause obesity: Adenoviruses are responsible for a host of ills, from upper respiratory tract problems to gastrointestinal troubles. It also seems to increase the number of fat cells in the body as well as the fat content of these cells.
  9. Cookies really are addictive: When subjects at Monell Chemical Senses Center in Philadelphia were shown the names of foods they liked, the parts of the brain that got excited were the same parts activated in drug addicts.
  10. Pick a diet, any diet: What really matters is your ability to moderate your intake of food. Feel free to use your favorite full-fat salad dressing, but your lettuce shouldn’t be swimming in it. You can cut carbs, fats, or just calories in general.
All About…Your Heart
It’s a sad fact that heart disease is the number one killer in the United States; what most people don’t realize is how preventable it is. Learn these facts, then do your part to protect your heart.
  1. Laughter is therapeutic: Watching a funny movie for even 15 minutes can increase your blood flow. Remember to laugh every day—it can keep your heart happy and healthy.
  2. Chest pain isn’t the only sign of a heart attack: Symptoms for most heart attacks include mild chest pain, some shoulder discomfort, or shortness of breath. Other signs can be nausea, lightheadedness, or breaking out in a cold sweat
  3. If you’re over 20, you should know your cholesterol level: If it’s high, there are treatments (including medication and exercises) that can help. You should also get your blood pressure and your blood sugar levels checked regularly.
  4. Obesity often leads to type 2 diabetes: Research has shown that eating more fruits, vegetables, and fiber can actually change the blood’s sensitivity to insulin within as little as two weeks.
  5. Walking can save your life: A recent study found that a sedentary 40-year-old woman who begins walking briskly half an hour a day, four days a week, can enjoy almost the same low risk of heart attack as a woman who has exercised regularly her entire life.
  6. Children can suffer from hypertension, too: About five out of every 100 children have higher than normal blood pressure.
You Have Super Powers!
Believe it or not, we’ve all got a little Clark Kent in us somewhere!
  1. Super strength: Your fight-or-flight capacities point toward fighting, you can do the things you’ve heard of in the news, like lift cars off of your loved ones or push 600-pound boulders out of your way.
  2. Supersonic hearing: Echolocation–it’s the way people with visual impairment continue to do amazing things. A prime example of this hidden sensory super power is Daniel Kish, a mountain biker who has been completely blind his whole life. He bikes better and faster than most people with vision, all by using sound to mentally paint a picture of the world around him. He does it so fast he can avoid trees, boulders and bears while speeding down the side of a mountain.
  3. Super memory: Your brain technically has the ability to store every single thing you’ve ever seen or heard or experienced.
  4. Super pain threshold: In moments of shock and trauma, your brain flips off pain like a switch. Ask somebody like Amy Racina, who fell off a cliff, landing six stories below, shattering her knee and breaking her hip. Not feeling more than minor pain, even with broken bone jutting out from her skin, she dragged herself until she found help. It was only at the point when she was being loaded safely into a helicopter that the pain returned.
  5. Time manipulation: How fast time moves for you is literally all in your head. Experts say it’s because your brain has two modes of experiencing the world, rational and experiential. Read more about these modes and how they could save your life.
All About…Skin
These fantastic (but not-so-appetizing) facts will have you thinking twice every time you look in the mirror.
  1. Weight game: An average adult’s skin spans 21 square feet, weighs nine pounds, and contains more than 11 miles of blood vessels.
  2. Sweating like a…human: The skin releases as much as three gallons of sweat a day in hot weather. The areas that don’t sweat are the nail bed, the margins of the lips, the tip of the penis, and the eardrums.
  3. Take a bath: Body odor comes from a second kind of sweat— a fatty secretion produced by the apocrine sweat glands. The odor is caused by bacteria on the skin eating and digesting those fatty compounds.
  4. The perfect crime: Some people never develop fingerprints at all. Two rare genetic defects, known as Naegeli syndrome and dermatopathia pigmentosa reticularis, can leave carriers without any identifying ridges on their skin.
  5. Hold your breath: Globally, dead skin accounts for about a billion tons of dust in the atmosphere. Your skin sheds 50,000 cells every minute.
  6. It can see: In blind people, the brain’s visual cortex is rewired to respond to stimuli received through touch and hearing, so they literally "see" the world by touch and sound.
  7. Master race, my melanin!: White skin appeared just 20,000 to 50,000 years ago, as dark-skinned humans migrated to colder climes and lost much of their melanin pigment.
  8. You see very, very white people: Albinos are often cast as movie villains, as seen in The Da Vinci Code, Die Another Day, The Matrix Reloaded, and—inexplicably—the 2001 flick Josie and the Pussycats. Robert Lima of Penn State suggests that people associate pale-skinned albinos with vampires and other mythical creatures of the night.
  9. Who needs keys?: More than 2,000 people have radio frequency identification chips, or RFID tags, inserted under their skin. The tags can provide access to medical information, log on to computers, or unlock car doors.
  10. You’re reading what?!: The Cleveland Public Library, Harvard Law School, and Brown University all have books clad in skin stripped from executed criminals or from the poor.
All About…Hygiene
Throughout history, humans have evolved to become cleaner, healthier, and fresher-smelling beings, but we’re certainly not sterile. These somewhat-disturbing (but very interesting) hygenic truths might have you showering more often than ever before.
  1. We’re really dirty: The human body is home to some 1,000 species of bacteria. There are more germs on your body than people in the United States.
  2. Be careful what you wash with: Antibacterial soap is no more effective at preventing infection than regular soap, and triclosan (the active ingredient) can mess with your sex hormones.
  3. Pee like an Egyptian: Ancient Egyptians and Aztecs rubbed urine on their skin to treat cuts and burns. Urea, a key chemical in urine, is known to kill fungi and bacteria.
  4. You might want to skip the fountain drink: There are more bacteria in ice machines at fast-food restaurants than in toilet bowl water.
  5. Floor food isn’t good: There’s no “five-second rule” when it comes to dropping food on the ground. Bacteria need no time at all to contaminate food.
  6. TV can kill: TV remotes spread antibiotic-resistant Staphylococcus, which contributes to the 90,000 annual deaths from infection acquired in hospitals.
  7. Make sure your doctor washes his hands: It is now believed President James Garfield died not from the bullet fired by Charles Guiteau but because the medical team treated the president with manure-stained hands, causing a severe infection that killed him three months later.
  8. Mount Soapo: Soap gets its name from the mythological Mount Sapo. Fat and wood ash from animal sacrifices there washed into the Tiber River, creating a rudimentary cleaning agent that aided women doing their washing.
  9. Sorry, Mom: Up to a quarter of all women giving birth in European and American hospitals in the 17th through 19th centuries died of puerperal fever, an infection spread by unhygienic nurses and doctors.
  10. Don’t forget to floss: The first true toothbrush, consisting of Siberian pig hair bristles wired into carved cattle-bone handles, was invented in China in 1498. But tooth brushing didn’t become routine in the United States until it was enforced on soldiers during World War II.
All About…Sex and Gender
Click on these links, and you’ll get a whole new take on gender, sexuality, and the complexity of human relationships.
  1. What were they waiting for?: Life emerged on earth about 3.8 billion years ago, but sex did not evolve until more than 2 billion years later.
  2. Why does it take two?: Scientists are not sure, since asexual reproduction is a better evolutionary strategy in some important ways.
  3. Better for your liver than tylenol: Sex cures headaches. Endorphins released into our bloodstream when we have sex not only give us pleasure but also act as painkillers.
  4. Coo-coo for cocoa: 70% of women would rather eat choclate than have sex.
  5. Staying alive: Sex wards off heart attacks. Frequent sexual intercourse (twice or more per week) lowers your chance of a fatal heart attack.
  6. It’s actually a cure-all: It also decreases pain from menstrual cramps and arthritis. It increases levels of endorphins and corticosteroids, raising pain thresholds.
  7. Calm yourself: Sex reduces stress, so try to make time for it at least a few times a week.
  8. What’s love got to do with it?: Sexual arousal and romantic love activate quite distinct areas of the brain—and love is clearly the more powerful. The latter turns on dopamine-rich regions linked with motivation, and falling in love is not unlike the rush of taking cocaine, hence the addictiveness of a new crush, and the withdrawal-like symptoms of love lost.
  9. Curious?: Recent research suggests women may be “intrinsically bisexual,” and the higher their libido, the more they desire both sexes.
  10. Asexuality 101: One percent of adults have zero interest in sex and have never felt sexually attracted to anyone at all.
All About…Mental Health
Mental health and sickness is a big part of being human. Though it’s been looked at and discussed with ridicule in previous generations, today’s world should know these important facts about human psychology and psychiatry.
  1. Mental illness is more common than you think: The National Institute of Mental Health reports that One in four adults-approximately 57.7 million Americans-experience a mental health disorder in a given year.
  2. Adults aren’t the only ones who suffer: The U.S. Surgeon General reports that 10 percent of children and adolescents in the United States suffer from serious emotional and mental disorders that cause significant functional impairment in their day-to-day lives at home, in school and with peers.
  3. Mental illness strikes young: Mental illness usually strike individuals in the prime of their lives, often during adolescence and young adulthood. All ages are susceptible, but the young and the old are especially vulnerable.
  4. It’s expensive: The economic cost of untreated mental illness is more than 100 billion dollars each year in the United States.
  5. It’s treatable: Most people who live with serious mental illnesses can significantly reduce the impact of their illness and find a satisfying measure of achievement and independence.
  6. Act fast: Early identification is of vital importance to treatment.
  7. Don’t be bullied: Stigma erodes confidence that mental disorders are real, treatable health conditions.
  8. Bipolar disorder is blind to gender: Over 10 million people in America have bipolar disorder, and the illness affects men and women equally.
  9. Suicide is serious: Each year in the U.S., approximately 2 million U.S. adolescents attempt suicide, and almost 700,000 receive medical attention for their attempt.
  10. Seasonal Affective Disorder (SAD) might be genetic: Many people with SAD report at least one close relative with a psychiatric condition, most frequently a severe depressive disorder (55 percent) or alcohol abuse (34 percent).
All About…Working Out
You already know how essential physical fitness is, and how important it is to take care of your body. But we’re willing to bet you didn’t know all of these bits of information about how to work out in a way that benefits you best.
  1. Incline builds muscle: Get off the flats and into the hills. Walking uphill makes you stronger.
  2. Treat your feet: Each step puts up to 1.5 times your body weight on your feet, which are shock absorbers that bear 60 tons of pressure every mile you travel.
  3. Lub-dub: The more fit you are, the harder it is to reach your target heart rate.
  4. Work it, girl: A 145-pound woman walking briskly (4 mph) burns 82 calories every 15 minutes.
  5. Getting back in: If you’ve taken off more than one month from exercising, give yourself at least four weeks to regain endurance and strength. Start slow, and increase your time, distance and intensity gradually, even if you were previously well-trained.
  6. Caffeine won’t kill: Despite popular thinking, caffeine doesn’t cause dehydration during exercise. In fact, the caffeine in a cup of tea or coffee improves speed and endurance.
  7. Change it up: Running on a circular track puts stress on the outside of your foot. Alternate the direction you run every other day or every five laps.
  8. Tums, anyone?: Strenuous exercise can cause acid reflux in healthy, conditioned athletes.
  9. Go shopping: Keep the spring in your step. Replace your running shoes every 300 to 400 miles.
  10. You’re not a camel: If you’re dehydrated even 5%, your metabolism can fall 20% to 30%. You’ll fire more easily and be irritable.
All about…Preventing Cancer
Cancer is the number two killer of people in the United States, but it doesn’t have to put you in the ground, too. Follow these healthy tips to treat your body to a longer, healthier life.
  1. Serve sauerkraut at your next picnic: The fermentation process involved in making sauerkraut produces several other cancer-fighting compounds, including ITCs, indoles, and sulforaphane. To reduce the sodium content, rinse canned or jarred sauerkraut before eating.
  2. Eat your fill of broccoli, but steam it rather than microwaving it: Broccoli is a cancer-preventing superfood, one you should eat frequently. But microwaving broccoli destroys 97 percent of the vegetable’s cancer-protective flavonoids.
  3. Toast some Brazil nuts and sprinkle over your salad: They’re a rich form of selenium, a trace mineral that convinces cancer cells to commit suicide and helps cells repair their DNA.
  4. Add garlic to everything you eat: Garlic contains sulfur compounds that may stimulate the immune system’s natural defenses against cancer, and may have the potential to reduce tumor growth. Studies suggest that garlic can reduce the incidence of stomach cancer by as much as a factor of 12!
  5. Eat cantaloupe: Cantaloupe is a great source of carotenoids, plant chemicals shown to significantly reduce the risk of lung cancer.
  6. Drink water: The amount of water women drink correlates to their risk of colon cancer, with heavy water drinkers reducing their risk up to 45 percent.
  7. Get about 15 minutes of sunlight each day: Getting too little vitamin D may increase your risk of multiple cancers, including breast, colon, prostate, ovarian, and stomach, as well as osteoporosis, diabetes, multiple sclerosis, and high blood pressure.
  8. Sprinkle scallions over your salad: A diet high in onions may reduce the risk of prostate cancer 50 percent. But the effects are strongest when they’re eaten raw or lightly cooked.
  9. Make a batch of fresh lemonade or limeade: A daily dose of citrus fruits may cut the risk of mouth, throat, and stomach cancers by half, Australian researchers found.
  10. Take advantage of your friends and family (they won’t mind): Men with high levels of stress and those with less satisfying contacts with friends and family members had higher levels of prostate-specific antigen (PSA) in their blood, a marker for the development of prostate cancer.
Weird Parts We Don’t Need
Evolution has gotten us pretty far, from our apelike ancestors to the upright walking, talking, complex thinking creatures we are today. But along the way, it left behind some traces of our previous forms, like extrinsic ear muscles and tail bones.
  1. Vomeronasal organ: A tiny pit on each side of the septum is lined with nonfunctioning chemoreceptors. They may be all that remains of a once extensive pheromone-detecting ability.
  2. Wisdom teeth: Early humans had to chew a lot of plants to get enough calories to survive, making another row of molars helpful. Only about 5 percent of the population has a healthy set of these third molars.
  3. Third eyelid: A common ancestor of birds and mammals may have had a membrane for protecting the eye and sweeping out debris. Humans retain only a tiny fold in the inner corner of the eye.
  4. Male Nipples: Lactiferous ducts form well before testosterone causes sex differentiation in a fetus. Men have mammary tissue that can be stimulated to produce milk.
  5. Body hair: Brows help keep sweat from the eyes, and male facial hair may play a role in sexual selection, but apparently most of the hair left on the human body serves no function.
  6. Female vas deferens: What might become sperm ducts in males become the epoophoron in females, a cluster of useless dead-end tubules near the ovaries.
  7. Fifth toe: Lesser apes use all their toes for grasping or clinging to branches. Humans need mainly the big toe for balance while walking upright.
  8. Coccyx: These fused vertebrae are all that’s left of the tail that most mammals still use for balance and communication. Our hominid ancestors lost the need for a tail before they began walking upright.
  9. Thirteenth Rib: Our closest cousins, chimpanzees and gorillas, have an extra set of ribs. Most of us have 12, but 8 percent of adults have the extras.
  10. Extrinsic ear muscles: This trio of muscles most likely made it possible for prehominids to move their ears independently of their heads, as rabbits and dogs do. We still have them, which is why most people can learn to wiggle their ears.