Regular readers of my scientific writing (thanks, Mom) or close followers of the Online Rocket may be aware that I wrote a piece this summer on the frustrating myth perpetuated in the media and in elementary school classrooms nationwide that humans only use 10 percent of their brain.
As I explained in my commentary, that statement is widely dismissed by neurologists and a complete myth.
“Evidence would show over a day you use 100 percent of the brain,” John Henley, a neurologist at the Mayo Clinic in Rochester, Minnesota was quoted in an article by Scientific American. A survey by the Michael J. Fox Foundation found that almost 65 percent of Americans believe that people only use 10 percent of their brains on a daily basis.
This is just one myth regarding science that plagues the minds of the general public, so I decided to pick out some of my least favorite myths to debunk in this week’s “It’s Rocket Science.”
Cracking your knuckles causes arthritis.
I was actually born with the unique characteristic of knuckles that crack anytime I want them to. I actually am incapable of clenching my hand into a fist without cracking my knuckles. As such, I’ve done my research on knuckle cracking. There have been no studies supporting the notion that cracking your knuckles causes arthritis, however it has been found that habitual knuckle cracking may result in swelling of the hand or lower grip strength.
So what happens when you crack your knuckles? According to the Journal of Chemical Education, cracking your knuckles releases gasses dissolved in the synovial fluid of joints which results in the popping noise associated with the crack.
Gum takes seven years to digest.
Actually, you never really “digest” gum at all. It just passes through your system, undigested. Nothing bad happens under normal circumstances from the swallowing of gum, and it certainly doesn’t “stick” around for seven years (bad pun, I know). “Most people empty their stomachs 30 to 120 minutes after eating, and that includes gum,” said Duke gastroenterologist Nancy McGreal in a debunking of the myth on the school’s website.
How Stuff Works explains, “It’s the gum base that sticks around. Gum base is made mostly of synthetic chemicals, and these chemicals give gum its chewy property. It’s designed to resist the digestive properties of the saliva in your mouth. But once it’s swallowed, even the gum base is subjected to the same treatment as regular food, and after it’s recognized as useless by your digestive system, it goes the same route as any waste product.”
Long story short, feel free to swallow your gum if you want.
Lightning never strikes the same place twice.
“Lightning does hit the same spot more than once, contrary to folk wisdom,” according to the National Severe Storms Laboratory. They attribute this to a number of possibilities including the terrain shape, local environmental factors or a statistical “fluke.”
NASA released a document in 2003 declaring that lightning does strike the same place more than once. Accuweather also published a commentary on the myth, stating that the Empire State Building is struck by lightning hundreds of times in a year.
The odds of being struck in your lifetime (estimated to be 80 years) are 1 in 3000; however, my high school librarian was struck by lightning on at least two occasions, according to eyewitness accounts (though rumors spread of upwards of five occasions). So, lightning can also strike the same person more than once.
Hippos lay eggs.
The common hippopotamus, Hippopotamus amphibius, actually has a gestation period of 243.5 days, or just a little less than eight months, before giving birth to their live young. The calf is 50 to 110 pounds at birth. Have I mentioned that I’m glad I’m not a female hippo?
Other fun facts about hippos include that they cannot actually swim, despite moving through water, the word “hippopotamus” comes from the Greek word for “water horse” or “river horse,” and they secrete an orange-red liquid that serves as an antibiotic, sunblock and moistener. That’s right, hippos have red sweat – it’s not blood.
A lot of these and other science myths don’t make sense if a person takes a moment to think about them. If there’s one thing that being in the field of science has taught me, it’s to question everything. So remember to ask questions, do research and find answers. As my favorite science communicator, Joe Hanson, says, “stay curious.”