A Skeptical Engineer
Myths from Our Childhoods

Myths from Our Childhoods

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There are several myths many of us have believed since grade school. Fortunately, these myths aren’t the type that might typically lead to trouble. Here are three that still resonate with people today:

Myth #1: Bats are blind. There’s no doubt many bats use echolocation to hunt prey, and they do so in the dark. So it seems reasonable that bats might not need vision. But zoologists who study bats say these creatures have extremely good eyesight. Their retinas have plenty of rods, useful for night vision, as well as two types of cones. One type is for daylight vision, and the second lets them see in the UV spectrum. UV vision comes in handy for finding the right plants with edible fruit and nectar, many of which reflect UV light.

Myth #2: Milk is good for growing strong bones. Milk contains calcium. Bones contain calcium. So milk must be good for growing bones, right? Not according to scientists at the Physicians Committee for Responsible Medicine. They did a meta-study examining much of the research done on the topic and concluded that: “Neither increased consumption of dairy products nor total dietary calcium consumption has shown even a modestly consistent benefit for child or young-adult bone growth.” And a scientist at Cornell University found that countries with the highest consumption of cow’s milk have the worst bone health overall.

It is true that calcium strengthens bones, but drinking milk is not the best way to get it. And other factors, including exercise, hormone levels, protein intake, heredity, and intake of vitamins D and K affect bone growth much more than milk consumption.

Myth #3: The Coriolis Effect determines how water drains from a toilet. Water swirls counterclockwise as it leaves toilets in the northern hemisphere and goes clockwise in the southern hemisphere. At least that’s the story. But it’s false. The Coriolis Effect, caused by Earth spinning on its axis, does affect some things. But to be affected by the Coriolis Effect, an event must be large, cover lots of ground, or go on for long periods of times. Cyclones and hurricanes, for example, are large enough to be affected by it. But water in a sink or toilet, not so much. Drains and taps in sinks and toilets are the main factors in determining how water leaves a container.

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