Prática de Shadowing: When Siberia thaws, what emerges? - Aprenda a falar inglês com vídeo
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You may have heard there's something lurking in the Arctic.
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In a remote part of Siberia.
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Hidden deep within the permafrost.
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A giant virus was unearthed.
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Dideljegernches.
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So-called zombie viruses.
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Zombie.
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Time-traveling.
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Zombie viruses.
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That have survived for thousands of years.
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And scientists are worried.
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They can unleash catastrophic consequences.
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That doesn't sound great, and I noticed that a bunch of our comments also mention this threat.
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So I decided to look into it.
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How much should we be worried about a new pandemic emerging from the permafrost?
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My research took me from mammoth meat to diamond mines to lost cities beneath the sea.
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And what I eventually found entombed in the permafrost was more fascinating than frightening.
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I'd like to share with you Adam's five steps for successful ancient zombie pandemic.
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Successful for humans or successful for the zombie virus? the microbe.
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So this is from the perspective of the microbe.
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Oh, fun.
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If you're an ancient bacteria or a virus and you want to make it big, your first step is to actually get preserved in the permafrost.
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Next, you have to survive being thawed and then come into contact with a human host.
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You need to successfully infect that human, but that's not enough.
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To cause a pandemic, you have to be able to spread human to human through the population.
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So I just want to go through each of these steps
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and talk about how likely they each are so we can see how much danger there actually is.
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Here is one of the earliest depictions of a woolly mammoth.
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Do you notice anything missing?
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The trunk!
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The trunk!
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It's missing a trunk!
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It's missing a trunk.
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This was not drawn by a scientist.
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This was drawn by a merchant who just happened to see a mammoth carcass.
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And it's actually not his fault that there is no trunk
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because it turns out that whenever Whenever a mammoth is exposed like this, most of the time its fleshy bits are immediately gobbled up by arctic foxes and other carnivores.
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In 1907 in Siberia, on the bank of this winding river, a mammoth was finally discovered with its trunk intact,
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and they actually set guards to protect this carcass.
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And I bring this up because I think it shows just how well preserved some of these finds are.
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After tens of thousands of years, the meat is still sort of edible.
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You can see their adorable fluffy little feet.
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There's milk in the stomachs of some of these calves.
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There's traces of blood.
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Is this how they're going to de-extinct it?
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Because they've got all of these good cells to work with.
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Yeah, I mean the DNA is still there.
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So much is so well preserved.
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And that's all thanks to this incredible storage device that we call the permafrost.
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Isn't permafrost just mud that's been frozen forever?
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Yeah, it can be soil that's been frozen for a few years, up to 700,000 years.
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It can be shallow or deep, and it covers this huge swath of the northern hemisphere.
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Below it is actually unfrozen ground, so as you go deep enough, the heat of the earth is actually keeping things thawed out.
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Oh, it's like a sandwich.
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It's an ice cream sandwich.
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And the top layer, which is freezing and thawing with the seasons, is called the active layer.
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It can have forests and wetlands, and it was once home to mammoths and rhinos and prehistoric humans.
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For thousands of years, a lot of those creatures somehow ended up getting stuck in the permafrost.
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And they stayed there until...
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Oooh.
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It looks like something flesh-eating.
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But this, I assume, is the top layer sort of caving in as the bottom layer also melts?
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Yeah, this is caused by thawing permafrost.
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I found this old, declassified spy run over Siberia from the 60s, and this chasm didn't even exist then.
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But then it thawed and eroded over a few decades.
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Wow, it's like a pretty clean cut.
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It kind of just went straight down.
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This leading edge, this little cliff, is still permafrost.
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As this thing collapses, they found all kinds of animals.
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They found mammoths, they found an ancient baby horse.
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And so, if you're approaching this question, are microbes preserved in the permafrost?
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Your hypothesis going in has got to be, of course, because it's preserving all these other things.
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And sure enough, back in 1908, when a Russian scientist took that famous trunk, extracted a little bit of mammoth snot, and looked at it under the microscope,
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he found the bodies of bacteria.
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There was also bacteria in samples from the soil around that mammoth.
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Now there's a chance this was contamination because sterilization protocols weren't standardized back then.
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But since then, there's been a ton of studies that have found the remains of bacteria and viruses in the permafrost. Were they alive?
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Well, that's the next question.
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That's step two of Adam's five steps for a successful pandemic.
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I want to put that question aside for a second and talk about a more personal one.
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How do you find a fulfilling career?
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Today's sponsor is unlike anything we've ever had.
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They're not trying to get you to buy anything.
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They're a nonprofit that wants to help you have a positive impact on the world.
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They're called 80,000 Hours, which is about the amount of time in the average career.
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And their mission, their entire reason for existing, is to help you find a satisfying job that will tackle some of the biggest problems facing humanity.
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I've been poking around on their website and it's a pretty incredible resource.
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They've got a curated job board that's constantly updated.
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They've got email templates for reaching out to people you actually want to work for.
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They've got a whole career guide that goes so far beyond the trite advice like follow your passion.
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And what I really like is that advice is based on over a decade of research.
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So I really encourage you to go to 80,000hours.org slash Howtown, you can click the link in our description,
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to get their free career guide and start making a plan for your high-impact life.
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Okay, now back to our pressing question.
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Can the microbes that are preserved in the permafrost be brought back to life?
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That is the same question this Russian scientist had.
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He immediately took his snot sample, put it in a Petri dish, and bacteria grew.
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Assuming there wasn't contamination, he showed that that bacteria came back to life and started growing.
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Yeah, which is a pretty big assumption, but luckily there are more recent examples.
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In 2015, scientists found a puppy buried in the permafrost.
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It was about 14,000 years old and had a little bit of woolly rhino in its stomach.
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When you said puppy, I thought it was going to be cute.
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It's not cute.
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No, it's pretty much a dirt clod, though it got slightly cuter once it got cleaned up.
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Was there something growing inside of this creature?
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Yes, they were able to extract and grow an ancient strain of a bacteria called Clostridium perfringens.
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The next year, 2,000 reindeer in northwest Siberia came down with anthrax.
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Anthrax is caused by bacteria, and they think that this came from a reindeer carcass that had sort of emerged from the permafrost.
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One thing about both of these bacteria is that they're both able to form spores.
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If the environmental conditions aren't ideal, they can create these little dehydrated, almost seeds with a tougher shell, and that helps them survive.
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And that's like the the Mike and Ike shape?
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Yes, exactly.
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So we've got a couple of these spore formers that have come back to life, but there have been other types too, mostly sycrophiles.
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Those are mostly non-threatening species that have adapted to cold soils.
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So there have been a bunch of zombie bacteria.
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But what about zombie viruses?
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To answer that question, we have to take a little detour to Bradford, England in 1992, where scientists discovered something they couldn't explain.
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They were looking for pathogens in a water sample when they came across these mysterious blobs.
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And at first they said, these are so big, they've got to be bacteria.
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Maybe this is a good time to do a little 101 on viruses and bacteria.
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Yeah, meet the microbes.
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Bacteria are these little, mostly single-celled organisms, but they're fairly complex.
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A typical species has thousands of genes.
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For comparison, here's a human cell, which has tens of thousands of genes.
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Viruses are usually tiny, almost like simple machines.
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Some have a couple hundred genes, but many have less than a dozen.
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And viruses are, like, alive, not alive?
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Is there a debate, or they're definitely not alive?
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Well, they're in this gray area in that they can't replicate alone.
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They have to sneak into cells of other species and trick their machinery into making more viruses.
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One of the ways that you find viruses is you can put them through a really fine filter.
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And basically, they're so small, they're the only things that make it through.
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But those blobs from Bradford didn't make it through the filter.
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And so the investigator thought, this is probably some weird little bacteria.
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But he was very smart because he didn't throw away the sample.
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He keep it in his fridge for more than 10 years.
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And then he sent it to Jean-Michel.
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My name is Jean-Michel John Michael Claverie from France.
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That's why I have that strange accent.
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I'm sorry about it.
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We discovered that in fact this bacteria was a virus.
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They called it the microbe mimicking virus or mimi virus.
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The genome of that thing was also very big.
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It had about a thousand genes.
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So very weird.
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Never been seen before.
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I reorganized my laboratory totally at the time, looking everywhere to find out if we could find other viruses like that.
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The next one they found, they called the mama virus because it was slightly bigger.
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Cute.
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They found a megavirus, Pandora virus, and then Pac-Man virus, Lost City.
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That's its scientific name.
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Oh, I see it.
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But why Lost City?
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Well, it came from a hydrothermal vent that's called the Lost City.
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Okay.
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So all of these giant viruses that they found attack amoeba.
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So these scientists basically, they take the samples, they culture the sample with this amoeba, and they see what viruses grow.
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One day I saw a paper by a Russian team.
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This group in Russia found some seeds in an ancient Arctic ground squirrel burrow frozen in the permafrost.
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and they were able to take that tissue and coax out these plants.
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That's amazing.
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And when I saw that paper, I said, well, if they can revive a plant, we should be able to revive viruses that are at least as old.
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So they asked for a sample from this burrow, cultured it with an amoeba, and they got Pythovirus cybericum,
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this giant virus bigger than anything they've ever seen.
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And was this the first virus that was found in permafrost?
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This is the first one that was resurrected.
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Now they've found 15 of these giant viruses brought back from ancient times.
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The oldest virus we were able to revive is 50,000 years old.
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And what is the significance of them being giant?
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Are they more hardy?
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Well, this is one of the things.
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Some of the extra genes these giant viruses have code for proteins that make really thick outer layers.
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And maybe that's part of what's helping them survive.
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Well, so far, you haven't convinced me not to worry about this.
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Okay, yeah, well, we're only on step two, right?
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It seems pretty easy for them to find some viruses and bring them back to life.
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One big caveat to this, life outside the permafrost is pretty hard for a bacteria or a virus.
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As soon as they get exposed to heat, to light, and to oxygen, they will start to degrade.
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Some viruses are extremely fragile and will not survive more than a few minutes, up to a couple of hours.
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And you need to be able to find a suitable host in that time.
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The population of humans that lives on the permafrost is about 5 million.
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So it's sort of like the size of your hometown, Phoenix, but spread over an area the size of North America.
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So that lowers the odds that a microbe will encounter a human host.
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But the worry is that that could change a little bit.
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The Arctic has been warming about four times faster than the rest of the globe.
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The real danger is that because of the global warming, It is now possible to have a lot of industrial development in the Arctic.
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This is a giant open pit mine for diamonds.
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They actually used jet engines to melt the permafrost to get through
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that layer and down into the layer they wanted to mine.
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These are multi-story buildings on this rim.
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Wow.
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You put 100,000 people in places where there was nobody there before.
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All those little dots are just houses.
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you're radically increasing the likelihood that you'll encounter some sort of virus or bacteria.
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Yeah, they don't have to do much.
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The people will come to them.
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But it's not enough to just meet a human.
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You have to be able to infect them.
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And most bacteria in the permafrost can't infect us.
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They just don't have the equipment to do so because they evolved to thrive in cold dirt.
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And most viruses in the permafrost evolved to attack those bacteria, or in the case of the giant viruses, amoeba.
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And that means they probably can't infect humans either.
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Amoeba are extremely distant from us.
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We diverged about 1 billion years ago from them.
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And we only diverged from cats and dogs around 90 million years ago.
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When your cat or if your dog got sick, you usually don't get the disease of your dog or your cat.
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The chance that any virus capable of infecting an amoeba would be able to infect a human is extremely unlikely.
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And the viruses that do infect people don't have those thick, tough shells.
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Viruses that infect nice, warm-blooded hosts, they don't have any protective mechanisms.
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Smallpox actually is a great test case because the smallpox virus is known for being extremely hardy.
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They used to preserve smallpox scabs and use those to inoculate people with them
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and they They would survive for a long time.
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Right, right.
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This is the original vaccine, right?
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Yeah.
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In 2004, researchers found the bodies of five 18th century smallpox victims buried deep in the permafrost.
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The first question, of course, that people had was if there was any evidence of live virus.
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And instead of trying to grow the virus, because that's dangerous for all sorts of reasons, what they used is DNA.
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If they found big, long pieces of virus DNA, that would be evidence that viable virus, would still be there.
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They were only able to find small, degraded viral bits, a few hundred A's, T's, C's and G's, which is really, really small.
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People also tried to do this with the 1918 influenza virus.
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There was an Alaskan village.
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The pandemic raged through, killed 72 out of the 80 people in the village over the course of five days.
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Wow.
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They had gold miners come and bury the bodies deep into the permafrost.
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Decades later, this scientist who was trying to understand the flu pandemic.
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He got permission from the village elders and retrieved tissue that was really well intact.
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Wasn't able to get any virus from them, though.
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They tried for decades.
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Eventually, with modern techniques, they were able to see that there were some scraps.
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Very small RNA fragments.
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No live virus at all.
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This is kind of the ideal scenario.
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If you're one of these viruses, you want to be frozen immediately after your host dies.
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You're immediately put in this super protective place.
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And then they only had to travel, in one case a few centuries, but in another case just decades into the future.
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And even under those ideal conditions, they didn't survive.
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And does the size of the flu virus and the smallpox, is the small size probably the reason why they didn't come back to life?
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If you don't have very many genes and you don't have very many proteins to work with, you've just got like the basic, you know, the basic shell.
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And that just isn't cutting it, it seems like, to keep you protected and make you survive.
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When it comes to bacteria, we have seen some that could potentially infect people.
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There was that anthrax outbreak in the reindeer, and some infected reindeer meat ended up sickening some people and even killing one boy.
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And in the case of that ancient puppy bacteria, that species can cause gas gangrene, though there's never been a case that was linked back to the permafrost.
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And we've never seen any evidence that the bacteria that cause big pandemics, the plague, tuberculosis, cholera, those bacteria that thrive in our warm,
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wet bodies, there's no evidence that they could survive in the frozen permafrost.
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In short, it's pretty hard for a human pathogen to even make it as far as step four.
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The only time we think that happened was that one anthrax outbreak.
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But even that wasn't enough to achieve a pandemic.
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A pandemic requires not just that one person gets infected from the environment, but that that turns into transmission throughout an entire population.
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So let's review our cast of microbes and see how many of the five steps each of them completed.
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Some bacteria, like the one that causes plague, likely wouldn't survive past step two.
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Most of the bacteria that do make it out of the permafrost don't infect humans, and the ones that can, like anthrax and clostridium, those aren't bacteria that you see being transmitted from person to person.
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That's just not how those particular bacteria work.
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The giant viruses from the permafrost don't infect humans, and we've seen that the smallpox and flu bugs were ripped to shreds before they could get that far.
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To make it further, any pathogen would also have to contend with the human technologies that can slow or stop transmission.
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Most antibiotics target these very foundational processes within bacteria that are conserved across the entire kingdom.
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Antibiotics probably are going to be able to get rid of those old bacteria.
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The same for viruses that we know about.
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If smallpox come back, yes, there will be a couple of problems, but we have a vaccine for the smallpox.
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So the big fear is of some unknown virus
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that somehow is able to make it through every single one of these steps and then become transmissible.
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Right, because it only takes one.
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Every single virus is different from the next one.
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So any single new virus poses its own problem.
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And that's why I'm more worried about viruses.
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And I'm more worried about viruses that we know nothing about, which are the old ones.
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It would take us a while to develop a vaccine that would be for that specific virus, probably.
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This is a real risk, but it's not any higher than the risk of some mysterious virus emerging from any ecosystem.
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It can't be completely discounted, but it's not something that's high on my concern list.
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There's unknown viruses in the ocean.
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There's unknown viruses in every corner of the world.
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And those corners of the world have a lot more living stuff in them.
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And they're changing all the time.
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And they're changing all the time.
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They're evolving.
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The permafrost is sort of like an archive of past pathogens, but the world is a living zoo of pathogens.
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I think that the risk from thawing permafrost is about the same as from regular soils.
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And if you look back to the history in the Arctic, for thousands and thousands of years, people have been using permafrost as food storage.
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People have been exposed to permafrost microorganisms for millennia.
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That's very comforting in a way.
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The bad news is that if you are worried about diseases and climate change,
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there's plenty to worry about because of warm weather microbes thriving and increasing their range as the temperatures increase, right?
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Yeah, I think that it probably couldn't hurt to like monitor the Arctic to try
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and make sure that we catch anything that comes out of it.
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But I'm much more worried about what you just talked about.
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Even within the existing range of an infectious disease, you know, something like warming temperatures can increase the time of the year when it can affect people.
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And we're talking a lot of times about diseases that we already know how to prevent, but we don't for the poorest people in the world, the people who also happen to be the least responsible for global warming.
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Even though I'm not going to lose any sleep over a permafrost pandemic, there's still plenty to worry about.
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But I think the thing
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that maybe you should think about as you're falling asleep instead is just how cool these giant viruses are
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and how much they like this whole other world of what
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it means to be a sort of living thing in the world that we don't really know much about.
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I mean, these viruses have hundreds, sometimes thousands of genes.
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That's a whole library of proteins that we don't didn't know about before
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that maybe could be useful to us or maybe could tell us something more about how life evolved.
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Well, I feel comforted because I do feel like there's a tendency to feel widespread doom about everything related to environmental change.
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It just takes a little bit of effort, as you've shown, to really parse through what to worry about, what not to worry about, where to focus, the resources.
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Sorry, there's a siren.
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As the sirens start.
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There's plenty to worry about in the world besides this.
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There's plenty to worry about.
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Zombie virus is like such a cool headline though.
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If you'd like to see us make more independent science journalism, there's a few free things you can do to help us out.
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One is of course subscribe, another is sign up for a free monthly newsletter on Patreon,
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and the last is to visit 80,000 hours.org slash Howtown to get their free career guide.
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Vocabulário e dicas de fala para esta lição
Este vídeo tem 305 frases e 3767 palavras para praticar shadowing. A fala dura 21:00. O falante fala em ritmo natural, cerca de 179 palavras por minuto, próximo de uma conversa do dia a dia. Apenas 80% das palavras estão entre as 3.000 mais comuns do inglês, por isso o vocabulário é exigente.
Vocabulário principal deste vídeo
15 palavras do vídeo que vale a pena aprender, com pronúncia e significado:
| Palavra | Pronúncia | Significado |
|---|---|---|
| virus substantivo | /ˈvaɪ.ɹəs/ | vírus |
| zombie substantivo | /ˈzɑmbi/ | morto-vivo, zumbi |
| layer substantivo | /ˈleɪ̯ɚ/ | camada |
| gene substantivo | /d͡ʒiːn/ | gene |
| preserve verbo | /pɹəˈzɝv/ | preservar |
| trunk substantivo | /tɹʌŋk/ | tronco |
| freeze verbo | /ˈfɹiːz/ | gelar, congelar |
| soil substantivo | /sɔɪl/ | solo |
| scientist substantivo | /ˈsaɪəntəst/ | cientista |
| evolve verbo | /ɪˈvɑlv/ | desenvolver, elaborar |
| ideal adjetivo | /aɪˈdi(ə)l/ | ideal |
| shell substantivo | /ʃɛl/ | concha |
| puppy substantivo | /ˈpʌpi/ | ratinho |
| vaccine substantivo | /vækˈsin/ | vacina |
| bury verbo | /ˈbɛɹi/ | enterrar, soterrar |
Phrasal verbs que você vai ouvir
| Palavra | Significado |
|---|---|
| end up verbo | terminar, acabar |
| clean up verbo | dar uma limpeza, limpar |
| come back verbo | voltar |
| find out verbo | descobrir |
| run over verbo | atropelar |
| throw away verbo | deitar fora, jogar fora |
| turn out verbo | terminar |
Pronúncia para ficar de olho
O falante usa 78 contrações e formas reduzidas, como they're, don't, they've. Diga-as na forma curta, do jeito que você ouve.
- Os sons de “th”: thrive /θɹajv/, thick /θɪk/, beneath /bɪˈniːθ/, northwest /nɔɹθˈwɛst/, threaten /ˈθɹɛt.n̩/
- Os sons de “sh” e “zh”: shell /ʃɛl/, transmission /tɹænsˈmɪʃən/, tissue /ˈtɪʃ.(j)u/, contamination /kənˌtæm.əˈneɪ.ʃən/, passion /ˈpæʃən/
- Palavras longas — acerte a sílaba tônica: mysterious /mɪˈstɪɹi.əs/, contamination /kənˌtæm.əˈneɪ.ʃən/, antibiotic /ˌæn.taɪ.baɪˈɑ.tɪk/, successfully /səkˈsɛs.fə.li/, potentially /pəˈtɛnʃ(ə)li/
Como praticar com este vídeo
- Ouça o vídeo inteiro uma vez sem falar e anote as palavras que você não conhece.
- Comece na velocidade 0,75×, faça shadowing frase por frase e volte à velocidade normal quando ficar fácil.
- Grave a sua voz e compare com o original, prestando atenção a palavras como virus, zombie, layer.
Gramática neste vídeo
As estruturas que o falante mais usa, com as palavras exatas do vídeo:
| Estrutura | No vídeo |
|---|---|
| Present perfect continuous have/has been + -ing — uma ação que começou antes e continua | I've been poking · has been warming · have been using |
| Present perfect have/has + particípio passado — uma ação passada que ainda importa agora | have survived · have found · have come |
| Voz passiva be + particípio passado — o foco está no que acontece, não em quem faz | was unearthed · being thawed · was not drawn |
| Orações relativas who / which + oração — informação extra sobre uma pessoa ou coisa | layer, which is · Hours, which is · Yeah, which is |
O que é a Técnica de Shadowing?
Shadowing é uma técnica de aprendizado de idiomas com base científica, originalmente desenvolvida para o treinamento de intérpretes profissionais. O método é simples, mas poderoso: você ouve áudio em inglês nativo e repete imediatamente em voz alta — como uma sombra seguindo o falante com 1-2 segundos de atraso. Pesquisas mostram melhora significativa na precisão da pronúncia, entonação, ritmo, sons conectados, compreensão auditiva e fluência na fala.