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  • This week, weve got a special video from our friends

  • at the American Association of Chemistry Teachers,

  • Featuring Sam Kean, the best selling author

  • behind The Disappearing Spoon.

  • Enjoy!

  • While science has done wonders

  • in solving mysteries about the world,

  • sometimes people twist those discoveries

  • into outlandish conclusions.

  • Instead of using evidence to prove a point,

  • people who believe in what’s called

  • pathological science use ambiguity as evidence

  • claiming that scientists don’t know everything,

  • and therefore there’s room for my pet theory, too.

  • That’s exactly what happened

  • with manganese and the megalodon.

  • In 1873 a research vessel called the HMS Challenger

  • set out from England to explore the pacific ocean

  • and pulled in tons of rocks, some shaped

  • like mineralized ice cream cones.

  • They were made of manganese.

  • When the crew cracked open the cones

  • they revealed the biggest, most pituitarily

  • freakish five-inch shark teeth they’d ever seen.

  • These teeth were later discovered by

  • paleontologists to belong to the long extinct,

  • fifty-foot long, fifty-ton megalodon.

  • All fine science so far.

  • The pathology started with the man- ganese.

  • It’s not clear why manganese galvanizes shark

  • teeththat is, why thin layers of this metal

  • deposit themselves on the teeth over time.

  • But scientists do know how quickly

  • the metal accumulates, and they deduced that

  • the teeth date from at least 1.5 million

  • years ago, meaning the megalodons

  • probably died out around then.

  • But some megalodon teeth had a

  • mysteriously thin manganese plaque,

  • about eleven thousand yearsworth.

  • Evolutionarily, that’s an awfully short time.

  • And really, what’s to say scientists won’t

  • soon find one from ten thousand years ago?

  • Or eight thousand years ago? Or later?

  • In the 1960s, a few enthusiasts with Jurassic Park

  • imaginations grew convinced that rogue megalodons

  • still lurk in the oceans.

  • megalodon lives!” They cried.

  • So why do people never see them?

  • Well, this myth suggested that megalodons

  • are supposed to be elusive, which gives people

  • a convenient escape hatch when asked why

  • the giant sharks are so scarce nowadays.

  • Unfortunately for big shark dreamers,

  • the idea crumbles under scrutiny.

  • Among other things, the teeth with thin

  • layers of manganese were almost certainly

  • torn up from old bedrock beneath the ocean

  • floor and exposed to water only recently.

  • Theyre probably much older

  • than eleven thousand years.

  • And although there have been legendary

  • eyewitness accounts of the beasts,

  • theyre all from sailors, notorious

  • storytellers, and the megalodons in their

  • stories vary manically in size and shape.

  • Overall, such stories depend on subjective

  • interpretations, and without objective

  • evidence, it’s not plausible to conclude

  • that megalodons, even a few of them,

  • slipped through evolution’s snares.

  • The Disappearing Spoon by Sam Kean is

  • available at fine book stores everywhere.

  • Want more episodes of The

  • Disappearing Spoon series?

  • Head to teachchemistry.org and join the AACT.

This week, weve got a special video from our friends

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メガシャークはまだ存在するのか?(featuring Sam Kean) - 反応 (Do Mega Sharks Still Exist? (featuring Sam Kean) - Reactions)

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    Eating に公開 2021 年 01 月 14 日
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