They say you shouldn’t believe everything you read - especially on the internet.
We all love a fun fact or two like Neil Armstrong's hair which was sold for $3,000 in 2004 or that the longest English word is 189,819 letters long.
But, every now and then, a little white lie gets tossed in to make things sound more interesting.
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And there's one major science 'fact' that we have all fallen for.
YouTube channel Kurzgesagt - In a Nutshell illustrates the oldest lie floating across the science field that had us all fooled.
Did you know that your blood vessels taken together add up to 100,000 kilometres? This is enough to wrap them around planet Earth twice.
Sound familiar?
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It's crazy to imagine but not crazy enough to find it completely unbelievable.
Kurzgesagt explained that this factoid has been widely spread in books, articles, and all over Google results, though finding its actual origin proved tricky.
"All of your blood vessels, twice around the world. Small thing, big number," they explained in the video.
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This statement was everywhere but no scientist or author could reference the actual source it came from, for them only to reply that 'the number has been circulating for decades.' After hours of research and contacting textbook authors, they finally traced it back to a 1929 book called The Anatomy and Physiology of Capillaries by August Krogh.
Krogh's estimate was based on solid scientific experiments.
In a nutshell, he cut muscle samples from different animals and made some 'rule of thumb assumptions' from there.
"Today, we know that his assumptions about the density of capillaries in humans was quite off," Kurzgesagt added.
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"On top of that, he used a kind of idealised bodybuilder [...] and this finally gave him the very pleasing number of 100,000 km."
But was it true?
Well, no. Because Krogh was a world-renowned expert in his field, this number was taken and used over and over again thousands of times.
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"His incorrect number was used in scientific papers, spread and became dogma, eventually entirely detached from the original source," Kurzgesagt pointed out.
So, there you have it - don't believe everything you read.
Turns out, scientists published a recent paper to confirm the real truth that the "length of all capillaries in a human is somewhere between 9,000 and 19,000 km."
Viewers can't believe this debunking of such a commonly thrown-around lie with one claiming it as 'terrifying.'
"This is impressive and terrifying. Thinking that, some of the facts we are used to, maybe are just sentences we accept for true but they are not," someone commented.
"I recall recently hearing someone saying “The faster information is shared the more accurate it is” and this video is a perfect rebuttal to that," one viewer said.
"Now, THIS is scientifically beautiful! It really leaves one wondering how much else we repeat in academia that is incorrect or inaccurate, and how better knowledge and data could change things," added another.