シャドーイング練習: How Boring Was The Boring Billion Really? - 動画で英語スピーキングを学ぶ
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135 文
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No matter how boring or still a time may seem, the Earth is always in a state of constant change.
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The weather shifts by the minute, the tectonic plates are always moving, the odd volcano here or there will go boom, and ultimately even life itself has a pretty profound impact on what's happening.
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And as a result of all this motion, the Earth doesn't tend to stay the same for very long, and it's because of this
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that you'll find traveling back by just a few thousand years usually results in a place looking very different than the present.
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I mean, for example, even the massive Mississippi River is only a few thousand years old.
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And this led me to ask, what would happen if suddenly everything stopped?
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If there was a metaphorical pause button, so to speak?
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What would that be like?
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And the answer to that is, well, thankfully Mother Nature already has me covered for this hypothetical, as once upon a time, this actually happened.
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Everything essentially slowed to a halt.
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And did so for a very long time, by the way.
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A painstakingly long time.
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About one billion years, to be exact.
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And this strange era in history is often referred to as the barren or boring billion.
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Now, to be a bit more specific, because things can't truly come to a standstill, this was an extended eon in which the tectonic plates of Earth were relatively stable,
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the climate under a kind of stasis, and biological evolution grinded to a near halt.
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So it does sound pretty boring, right?
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And yet, this age of slowness wasn't really all that dull, and may have even been a huge win for the future of Earth.
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But when exactly did this all go down?
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I mean, 1 billion years is not exactly a blink-and-miss type of moment.
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Well, just like its duration, the boring billion occurred a long time ago as well, before the Mesozoic, Permian, or even the Cambrian,
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as it began about 1.8 billion years ago during the middle of the Proterozoic Eon.
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This within itself was not a geological period like the Cretaceous or Jurassic, but rather a massive eon, starting nearly 2.5 billion years back,
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and it largely involved an Earth that would be entirely foreign to any of us, and also extremely inhospitable, with the atmosphere back then being made up of just 1-2% oxygen,
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which in other words is about 10-20 times less than today.
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And thus, you'd only get to enjoy this time for about as long as you could hold your breath.
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And to go along with the deadly air, this period tended to be exceedingly hot as well, though at certain points it was also extremely cold,
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especially during the abnormal event known as the Huronian Glaciation, which was a massive ice age that makes the one that we are currently in looked like a giant choke,
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as it was so severe that it's possible that the entire surface of the planet was covered in ice, including the oceans, and leading to something known as the Snowball Earth Hypothesis.
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Now let's just say, the temperatures at that time would have made Antarctica seem like a tropical getaway,
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as even the equatorial regions of Earth may have been below minus 45 degrees Celsius or minus 49 degrees Fahrenheit, so in other words colder than the summit of Mount Everest.
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This ice age played out between 2.5 and 2.2 billion years ago, and largely coincides with another event within this eon,
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the Great Oxygenation Event, wherein it's believed that microbial photosynthesis for the first time led to an increased atmospheric oxygen amount, while then also decreasing the level of methane,
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which if you didn't know, is a very potent greenhouse gas, and thus potentially leading to this ice age.
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Miraculously though, even during a global period in which Antarctica looked warm, life managed to hold out during the Huronian Glaciation.
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And although it wasn't what I would consider the most interesting in paleo life, it was still vital to Earth's history, and largely consisted of single-celled prokaryotes,
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which we know about through actual paleobacteria and cyanobacteria fossils.
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So yes, bacteria fossils are a very real thing.
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But then, after the great oxygenation, more things started to show up finally, such as the first eukaryotes.
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In other words, organisms that have cells with membrane-bound nucleuses, which in essence encompasses all animals, fungi, seaweeds, plants, and more.
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And of course, this is cool and all, but what this really serves to show is that prior to the slowdown, some major things have been going down on the planet.
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But then about 1.8 billion years ago, as I said, it all just stopped, and thus the boring billion had begun.
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As far as researchers can tell, it explicitly transpired between the boundary between the Orocyrian and the Stathirian geological periods of the Proterozoic.
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And as I mentioned, it was characterized by a massive slowdown in tectonic activity, the stabilization of Earth's climate, and a near halt in evolution, relatively speaking.
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And in general, just about everything became stagnant, almost painfully, leading to this period often being dubbed as the dullest period of all time.
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So clearly, paleontologists were not in my calculus class, with not much happening or changing for a duration over 3,000 times longer than we humans have been around.
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But what exactly does that mean or look like?
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Well, in my very humble opinion, this time wasn't really as boring as it's made out to be.
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For starters, while tectonic activity did slow down, it did not completely stop, and at the start of the period, there might have even been the presence of a paleo-supercontinent.
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And no, I'm not talking about Pangaea, but rather the proposed continent of Colombia, which also goes by the name of Nuna,
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or Hudsonland, and was about 8,000 miles or 12,900 kilometers long from north to south, while then also largely being positioned in the northern hemisphere.
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And I don't know about you guys, but to me, there's just something about supercontinents that are fascinating.
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And if you waited long enough, you'd see Columbia gradually transform into the next supercontinent known as Rodinia, before then fragmenting.
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And mind you, this all took place within the boring billion.
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So again, things were happening and moving, but just slowly, with some estimates suggesting
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that the tectonic plates were moving along at a pace between 5 to 15 times slower than the present.
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And walking along this or these supercontinents would have been quite the trippy experience, as given the very severe stasis of things,
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most of Earth's landscapes during the Boring Billion were relatively flat, featureless, and barren.
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Kind of like that part of a video game's map that's pretty empty
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and is really just there to make the world seem bigger.
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However, with that said, while the overall gist of the time seemed to have been a whole lot of nothing, the lands didn't actually have a something, as you would find it ruled by life.
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Just not something we usually think as being rulers.
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And that would be slime.
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Yeah, during the Boring Billion, slime was all the rage, making Nickelodeon's slime fest look like somewhat of a pity party.
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And due to the stability at the time and lack of overall biological evolution, microbes and algae were going ape on land.
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With them being aided by vast dust storms, they provided both nutrients and a mode of transportation, resulting in the formation of vast layers of slime,
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that in essence might have covered large portions of the entire planet's surface, especially around coastal areas, rivers, and water sources.
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Which then arguably makes, paradoxically, this time to have been the least boring time to have viewed the planet from space.
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As going off of modern analogs, you would have been able to see biofilms of varying colors, including yellow, brown, green, blue, black, and more.
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Another area of variety you'd also find is depth, as many of these slimes likely formed laminated mats, meaning that over time, as living organisms in them died,
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the slime would slowly form new layers, with dead slime being on the bottom and living slime on top, and thus resulting in larger structures being created.
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And this does also mean
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that this was one of the very few times in Earth's history where life was present
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that you wouldn't have to worry about something eating you, rather you'd basically just have prehistoric Plato all around you.
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Yet naturally, slime can only be so interesting for so long, but if you did manage to pack a microscope to this time-traveling Plato adventure,
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you would soon realize it was a whole different story underneath the surface.
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Metaphorically, that is.
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As while onto the naked eye, the slime would look like it's doing a whole lot of nothing, on a microscopic level, a battlefield of untold proportions was raging on,
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and the stakes might have been a tad bit raised by the possible presence of one of Earth's first terrestrial eukaryotes, lichen, which fed directly on these slime mats.
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And along with the endless slime, you'd likely also spot the odd volcano or two erupting around the planet on occasion, which in itself would have been quite the sight.
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And no, not just because they're erupting in nigh-empty plains of slime, but rather because the rising ash would be a bit different than normal, primarily due to the sky, which was not like ours.
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Now granted, hypothesizing what the sky looked like over a billion years ago is quite hard, Yet, given the lower oxygen levels of the time,
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and the suspected higher levels of sulfur in the atmosphere, some researchers believe that the sky would have appeared dimmer and more hazy than the present,
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perhaps taking on a look at reminiscent dystopian futuristic cities, being choked by smog and leading to very vivid red,
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orange, and purple sunsets, like what you can see in today's polluted cities.
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But what truly would have come as a shock wasn't the sky or the barrenness of the lands, but rather the oceans and seas, as they too were anything but normal.
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And get this, possibly didn't even resemble water.
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And this is because oceans during the boring billion are believed to have been largely void of dissolved oxygen and nutrients, where it was rich in sulfides,
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meaning not a lot of stuff could live here.
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Yet, one thing that did manage, and actually thrived, was large amounts of purple bacteria.
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Yeah, purple bacteria.
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And these little guys were like Caesar from Planet of Apes, meaning strong together, and were able to complete photosynthesis in a way different than how plants achieve it,
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using hydrogen sulfide instead of water.
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And this worked nicely for them in these ancient oceans, but a byproduct of this alternative photosynthesis was sulfur instead of the usual good stuff,
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i.e. oxygen, and thus leading to what is dubbed as a Canfield Ocean, wherein the waters were eucinic, meaning both sulfitic and anoxic,
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while then it also seized the mineral deposition of iron-rich formations.
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And yes, I know this may just sound like a bunch of fancy words, but essentially what it resulted in was that rather than having the blue or sometimes green waters we were used to seeing,
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the water during the boring billion may have appeared black or milky turquoise.
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Ironically though, while this may have made the oceans look more deadly in a sense, swimming here would have been quite pleasant and safe.
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As for starters, the water on average throughout these boring billion years were slightly warmer than current surface temperatures,
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being about 4 degrees Celsius or roughly 7.2 degrees Fahrenheit hotter, meaning the average place would feel like the Maldives.
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You also have to remember
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that swimming in the oceans during the boring billion would make
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you the largest predator on the entire planet by a metric ton of magnitudes.
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And as such, you wouldn't have to worry about anything taking a bite out of you.
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So in essence, the world turned into a safe, heated pool that stretched out for thousands and thousands of miles in any direction.
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There is also some evidence that the salinity levels at the time were possibly double than what they are currently, meaning you'd float much easier, and sinking might have actually been a challenge to accomplish.
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However, with all this said, while a person would definitely be the largest organism on the planet, the waters weren't really empty, as along with our famous purple bacteria,
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you also had marine slime.
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Yeah, no matter where you went in the boring billion, slime was gonna follow you.
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And in the waters, this slime wasn't just limited to the seafloor, but it was also on the surface.
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Now thankfully, we aren't talking about every inch of the oceans being covered in slime, but along shallow shelves, coastlines,
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and calm patches, you could probably find extensive of sliming that mimic what we see in cyanobacteria blooms of today, just on a much larger scale.
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Another site that would have been common as well in this slime-ran world would have been stromatolites.
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These are interesting structures, which you can actually still see in various parts of the world, which form when sticky mats of microbes trap sediment over time,
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and continuously form new layers over the sediment, resulting in fossilized microbe mounds after a very long period of time.
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Now, they are pretty rare nowadays, but back then, they would have been absolutely abundant and are also among the oldest signs of life on Earth,
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with some being dated all the way back to 3.5 billion years ago.
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And the formation of these Dramatolites during the Boring Billion is some of that era's most important lasting relics, giving us insight that would otherwise be impossible.
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So yeah, even though not a lot was happening during the Boring Billion compared to later times, it was still arguably not that boring.
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I mean, a world ruled by slime is a win in my book, and as I teased out in the beginning, it was probably a win for the world in general as well.
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Because while not many breakthroughs in evolution occurred, some pretty major milestones did, including some of the earliest evidence for sexual reproduction and the emergence of something known as red algae,
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a very important group that still dictates the world's ecosystems even now.
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Additionally, we see that eukaryotes still diversified in this time, and that some of the earliest complex organisms appeared as well.
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So again, calling this time dull might have been a bit too harsh.
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I mean, you don't want to upset the slime overlords, do you?
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As you never know, they could make a comeback one day.
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However, they did fumble the bag, so maybe they won't.
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As despite having nearly full control of the Earth's surface, back then, King Slime would eventually yield the throne, as about 800 million years ago, the boring billion came to an end,
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shifting the landscape once more.
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And just like how it began, the ending of its story isn't exactly that climatic, as there was no major extinction event like a giant asteroid or a massive volcanic eruption that gave the Earth a facelift.
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No, instead one of the main hypotheses on what happened was rather just the slow breakup of the supercontinent Rodinia, which led to new shallow seas forming, and thus increasing the amount of coastline,
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and thus weathering, which essentially pulled down carbon dioxide and dumped new nutrients into the waters, leading to a rise in photosynthesis once more.
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On top of that, the splitting of the new landmasses led to habit fragmentation on land and in marine areas, which created new environments and also isolation, leading to a higher rate of speciation.
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And with that, the Earth was back to its more perky self, and the rest was history, natural history.
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このレッスンの語彙とスピーキングのポイント
このB2レベルのスピーキングレッスンは、動画「How Boring Was The Boring Billion Really?」を教材にしています。 繰り返し出てくる語は次のとおりです：billion, slime, boring。 この動画には、シャドーイング用の文が135文、単語が2666語あります。 音声の長さは13:18です。 話す速さは速く、1分あたり約201語です。音のつながりや弱く発音される音が多くなります。 英語の頻出3,000語に含まれる単語は79%だけなので、語彙は難しめです。
この動画の重要語彙
動画の中で特に難しい単語15語を、発音と意味つきで紹介します。
| 単語 | 発音 | 意味 |
|---|---|---|
| slime 名詞 | /slaɪm/ | ヘドロ |
| bore 動詞 | /boɹ/ | いらいらさせる |
| supercontinent 名詞 | 超大陸 | |
| bacterium 名詞 | /bækˈtɪəɹ.ɪəm/ | 細菌, バクテリア |
| photosynthesis 名詞 | /ˌfoʊ.toʊˈsɪn.θə.sɪs/ | 光合成 |
| organism 名詞 | /ˈɔɹ.ɡəˌnɪz.əm/ | 生物, 有機体 |
| eukaryote 名詞 | /juˈkæɹi.oʊt/ | 真核生物 |
| nutrient 名詞 | /ˈnuː.tɹi.ənt/ | 栄養, 栄養素 |
| mat 名詞 | /mæt/ | マット |
| essence 名詞 | /ˈɛsəns/ | 本質 |
| alga 名詞 | /ˈæl.ɡə/ | 藻類 |
| barren 形容詞 | /ˈbæɹən/ | 不妊の |
| erupt 動詞 | /ɪˈɹʌpt/ | 噴出する |
| microbe 名詞 | /ˈmaɪkɹoʊb/ | 微生物 |
| paleoconservative 名詞 | 旧保守 |
動画に出てくる句動詞
| 単語 | 意味 |
|---|---|
| go down 動詞 | 降りる, 降下する |
| hold out 動詞 | 待つ |
| pull down 動詞 | 引き下げる |
| show up 動詞 | 現れる |
| slow down 動詞 | 遅らせる |
この動画の文法
話し手がよく使っている文型を、動画の実際の表現とともに紹介します。
| 文型 | 動画での表現 |
|---|---|
| 受動態 be + 過去分詞 — 誰がするかより、何が起きるかに焦点を当てる | is often referred · being made · was covered |
| 関係詞節 who / which + 節 — 人や物について情報を加える | Glaciation, which was · sky, which was |
注意したい発音
話し手はyou'd, wasn't, didn'tなど、短縮形や弱形を28回使っています。聞こえたとおりの短い形で発音しましょう。
- 「th」の音: photosynthesis /ˌfoʊ.toʊˈsɪn.θə.sɪs/, methane /ˈmiːθeɪn/, hypothetical /ˌhaɪpəˈθɛtɪkəl/, underneath /ˌʌndɚˈniθ/, throne /θɹəʊ̯n/
- 「sh」と「zh」の音: shallow /ˈʃæloʊ/, duration /dʒʊˈɹeɪ.ʃən/, deposition /ˌdɛp.əˈzɪʃ.ən/, eruption /ɪˈɹʌpʃən/, extinction /ɪkˈstɪŋkʃən/
- 長い単語（アクセントの位置に注意）: photosynthesis /ˌfoʊ.toʊˈsɪn.θə.sɪs/, organism /ˈɔɹ.ɡəˌnɪz.əm/, eukaryote /juˈkæɹi.oʊt/, geological /ˌd͡ʒi.əˈlɑdʒ.ɪk.əl/, characterize /ˈkɛɹəktəɹaɪz/
日本語話者が苦手な音：
- /r/ と /l/ の区別 — /l/ は舌先を歯茎につけ、/r/ はどこにもつけない: arguably /ˈɑɹɡjuəbli/, abnormal /ˌæbˈnɔɹ.ml̩/, resemble /ɹɪˈzɛmbəl/, ironically /aɪˈɹɑnɪkli/, ruler /ˈɹulɚ/
- /v/ — /b/ にならないように、上の歯を下唇に当てる: volcano /vɑlˈkeɪ.noʊ/, dissolve /dɪˈzɑlv/, volcanic /vɔlˈkænɪk/, vivid /ˈvɪvɪd/, void /vɔɪd/
- /f/ — 「フ」ではなく、上の歯と下唇で出す: photosynthesis /ˌfoʊ.toʊˈsɪn.θə.sɪs/, sulfur /ˈsʌl.fə/, fossil /ˈfɑsl̩/, fascinate /ˈfæsɪneɪt/, hemisphere /ˈhɛmɪsfɪə/
この動画での練習方法
- まず声を出さずに動画を最後まで聞き、知らない単語をメモします。
- まず0.75倍速で一文ずつシャドーイングし、慣れてきたら通常の速度に戻します。
- 自分の声を録音して元の音声と比べます。slime, bore, supercontinentなどの単語に特に注意しましょう。
シャドーイングとは？英語上達に効果的な理由
シャドーイング（Shadowing）は、もともとプロの通訳者養成プログラムで開発された言語学習法で、多言語習得者として知られるDr. Alexander Arguelles によって広く普及されました。方法はシンプルですが非常に効果的：ネイティブスピーカーの英語を聞きながら、1〜2秒の遅延で声に出してすぐに繰り返す——まるで「影（shadow）」のように話者を追いかけます。文法ドリルや受動的なリスニングと異なり、シャドーイングは脳と口の筋肉が同時にリアルタイムで英語を処理・再現することを強制します。研究により、発音精度、抑揚、リズム、連音、リスニング力、そして会話の流暢さが大幅に向上することが確認されています。IELTSスピーキング対策や自然な英語コミュニケーションを目指す方に特におすすめです。