Useless trivia and facts

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You inhale 50 potentially harmful bacteria every time you breathe. Thankfully, your immune system is working hard all the time, so virtually all of these are promptly destroyed without you feeling a thing. Phew.

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You can see stars as they were 4,000 years ago with the naked eye. Without a telescope, all the stars we can see lie within about 4,000 light-years of us. That means at most you’re seeing stars as they were 4,000 years ago, around when the pyramids were being built in Egypt.

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Plants came before seeds. According to the fossil record, early plants resembled moss and reproduced with single-celled spores. Multicellular seeds didn’t evolve for another 150 million years.

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Our dead cells are eaten by other cells in our body. Don’t worry; it’s meant to happen. When cells inside your body die, they’re scavenged by phagocytes – white blood cells whose job it is to digest other cells.

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Smells can pass through liquid. Please don’t try smelling underwater (your nose will not appreciate it), but smell does protrude through liquid.

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Bats aren’t blind. Despite the famous idiom, bats can indeed see, but they still use their even more famous echolocation to find prey.

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Hibernating animals don’t dream. Sleep is a more physiologically ‘active’ state than hibernation, which requires animals to substantially reduce all activities to conserve energy. There’s simply not enough brain activity while an animal is hibernating to enable dreaming. The only exception to this rule is the fat-tailed lemur.

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Pine trees can tell if it's about to rain. Next time you see a pine cone, take a close look. If it’s closed, that’s because the air is humid, which can indicate rain is on its way.

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You can’t fold a piece of A4 paper more than eight times. As the number of layers doubles each time, the paper rapidly gets too thick and too small to fold. The current world paper-folding record belongs to California high school student Britney Gallivan, who in 2002 managed to fold a 1.2km-long piece of tissue paper 12 times.

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The sharpest teeth in history didn’t belong to sharks or even dinosaurs. They came from conodonts – tiny eel-like creatures that lived 500 to 200 million years ago. Their tooth tips were just two micrometres wide, about 1/20th the width of a human hair, making them the sharpest ever measured.