Excerpted from Deceived Wisdom: Why What You Thought Was Right Is Wrong by David Bradley ($19.95, Elliott and Thompson)
There is much deceived wisdom in the world - from fitness fallacies to dietary deceptions and countless miscellaneous misconceptions.
Given that human beings are inquisitive by nature, it might seem odd that there is so much misinformation swirling around and confusing us, but perhaps it’s not that surprising. We have come to expect definitive answers to our questions in an instant rather than having to puzzle over a problem and work it out for ourselves, and it’s tempting to reach for an instant answer without worrying about whether it’s right or not.
Here are seven pieces of deceived wisdom that aren’t actually true:
Lightning never strikes the same spot twice
The maintenance team at the Empire State Building in New York City will testify that their building is struck by lightning at least twenty-five times each year. Other high points on the landscape suffer an equally discouraging succession of bolts from the skies, and there are several reports of people who have survived multiple strikes. Worldwide, there are about thirty lightning strikes that reach the ground every second. It is perhaps therefore not surprising that lightning strikes the same place more than twice quite often.
Chemical-free products are better for you
There is no such thing as ‘chemical-free’: everything you can touch (and everything you can’t, is made of chemicals. Water is a chemical, as is the oxygen in the air we breathe, the cellulose in grass, the sand on the beach, your fingernails, your eyelashes, your brain. Moreover, ‘natural’ does not equate to ‘safe’: think snake venom, deadly nightshade, jellyfish stings and asbestos.
Household dust is mostly skin
The precise composition of house dust depends on where you live, but it can be a mixture of dust from building materials, sand, soil, clothing fibers, plant fibers, fragments of hair (animal and human), pollen and insect feces. Only a tiny fraction is formed from flakes of human skin.
Shaving makes hair grow back thicker
Hair is dead tissue, so shaving can have no effect on the shape or size of the follicles from which the hair grows. If this deceived wisdom were true, bald men would shave their heads regularly in order to remedy their lack of cranial hirsuteness.
Hair and fingernails continue to grow after death
Hair and fingernails require there to be living cells in the hair follicles and in the bed of the fingernails if they are to grow. As with all the other cells in a corpse, these cells die when the person dies. For several days after death, the skin and tissues of a body dry out and shrink, so largely dead tissues such as hair and nails may appear to protrude more from the follicles and fingers, but this is not actual growth.
It’s too cold to snow
Nowhere on earth can be too cold for snow. Meteorologists know very well that it can snow at almost any temperature below a certain freezing threshold. Theoretically, if it were 273˚C below freezing, at absolute zero – the coldest anything could ever be – then it would not snow, but even in the deepest, darkest depths of the Antarctic winter it has not dropped below minus 90˚ C since records began. The Antarctic is certainly not at absolute zero; even deep space isn’t that cold.
If food dropped on the floor is there for five seconds or less, it’s still safe to eat it
Countless teenagers throwing caution to the wind and, naturally, ignoring parental advice, love to eat food like pizza, burgers and fries. And among teenagers there is the well-known opinion that food dropped on the ground and retrieved within five seconds is perfectly safe to eat, whether the pizza lands pan-side down or the cheese and tomato mix hits the pavement. Said in jest it may be, but there’s no denying that people follow it. Unfortunately, bacteria, viruses and the parasites present in animal feces, which are so often smeared on pavements in town centers, can survive for long periods on dirty surfaces. Germs are much faster-moving than even the sportiest of teenager stoked up on fries and will clamber aboard any dropped food within much less than five seconds. When invoking the five-second rule, first think salmonella, toxicaria and E.coli before taking another bite.