シャドーイング練習: Why do Humans Have Different Skin Colors? - 動画で英語スピーキングを学ぶ
レッスンを作成中...
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It's roughly 200,000 years ago.
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You're a human.
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Not a king.
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Not a farmer.
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Not a philosopher.
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Just a regular homo sapiens, standing somewhere in East Africa, wondering where your next meal is coming from,
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and hoping nothing with larger teeth than you finds you first.
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And if you could somehow take a photograph of yourself and compare it to the 7 billion people alive today, one thing would immediately jump out.
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you probably wouldn't be white.
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You probably wouldn't be Asian.
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You definitely wouldn't be a redhead arguing with the sun every summer.
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In fact, the first modern humans almost certainly had dark skin.
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Which raises a surprisingly interesting question.
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If humanity started out with dark skin, where did all the other colors come from?
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Because today, humans range from extremely dark to extremely light, with every imaginable shade in between.
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Some populations developed lighter skin, some stayed darker, some evolved entirely different genetic solutions to the exact same environmental problem,
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and the story of how that happened is one of the strangest examples of evolution happening in plain sight.
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Let's start at the beginning, the original human color.
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Here's something many people don't realize.
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For most of human history, there was no such thing as a white person.
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Or a black person.
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Or an Asian person.
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Those categories are incredibly recent.
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For almost 90% of Homo sapiens history, everyone lived in Africa.
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And Africa has a lot of sunlight.
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An almost ridiculous amount of sunlight.
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The kind of sunlight that looks pleasant on vacation,
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but can quietly destroy your DNA if you're exposed to it constantly over thousands of generations.
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Which is exactly why melanin exists.
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Melanin is the pigment that gives skin its darker color.
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More importantly, it's basically nature's sunscreen.
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It absorbs harmful ultraviolet radiation before that radiation can damage cells,
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destroy folate levels, and create all sorts of biological problems that evolution generally considers bad for survival.
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And in equatorial Africa, where UV radiation is among the strongest on Earth, having lots of melanin wasn't just useful,
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it was a massive evolutionary advantage.
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Generation after generation, individuals with darker skin were better protected from the environment around them.
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Over enough time, dark skin became the norm.
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Not because evolution had a preference.
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Evolution doesn't care about appearances.
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Evolution cares about one thing.
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Did you survive long enough to have children?
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That's it.
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That's the entire performance review.
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And for hundreds of thousands of years, dark skin was one of humanity's greatest biological assets.
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Then humans started moving.
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And that's where everything gets weird.
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The Great Migration Problem.
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Around 60,000 to 80,000 years ago, groups of humans began leaving Africa.
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Some traveled through the Middle East, others moved into Europe, others pushed eastward into Asia.
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Eventually humans would reach Australia, Siberia, and somehow decide crossing into the Americas was a reasonable idea.
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Which sounds impressive until you remember none of them had maps. Or compasses.
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Or Google Maps desperately recalculating every 10 seconds.
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They just kept walking.
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And as humans moved farther from the equator, something changed.
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The sunlight changed.
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Specifically, ultraviolet radiation became weaker.
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At first, this sounds fantastic.
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Less UV damage.
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Less risk.
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Problem solved.
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Except not quite.
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Because the same sunlight that can damage your skin also helps your body produce vitamin D.
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And vitamin D is incredibly important.
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Without enough of it, bones weaken.
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Immune systems suffer.
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Development becomes more difficult.
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You can survive with too little vitamin D.
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But evolution doesn't reward surviving, it rewards thriving.
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Suddenly, the very trait that had been incredibly useful in Africa was becoming less useful farther north.
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Dark skin blocked UV radiation extremely effectively.
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But in places with much less UV radiation to begin with, that protection came with a cost.
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needed to absorb more sunlight.
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And over thousands upon thousands of years, natural selection began favoring individuals with lighter skin.
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Not overnight, not in a few generations.
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We're talking about an evolutionary process that unfolded over enormous stretches of time — the whitening of Europe.
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Here's the really surprising part.
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The first humans who entered Europe were probably still fairly dark-skinned.
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Modern Europeans didn't immediately appear the moment humans crossed into the continent.
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For a long time, Europe was populated by people who would likely look very different from modern Europeans.
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Ancient DNA has completely transformed our understanding of this.
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Some hunter-gatherers living in Europe thousands of years ago appear to have had dark dark skin paired with blue eyes.
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Which sounds like evolution accidentally randomized a character creator screen.
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But that's what the evidence suggests.
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The pale skin, commonly associated with Europe today, became widespread much later.
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As farming spread, as diets changed, as populations mixed, as different genetic mutations increased in frequency.
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Eventually, lighter skin became common across large parts of Europe
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because it helped maximize vitamin D production in regions with relatively low sunlight.
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Not because it was better, not because it was superior, simply because it worked better under those environmental conditions.
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That's evolution in a nutshell.
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No master plan, just adaptation.
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Now, here's where things get even stranger.
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Asia solved the same problem, differently.
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The Asian shortcut.
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Imagine two students taking the same math test.
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Both get the correct answer, but they use completely different methods.
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That's basically what happened with Europeans and East Asians.
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Both populations evolved lighter skin compared to their African ancestors.
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But many of the genetic changes responsible are different.
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They arrived at similar outcomes through separate evolutionary pathways.
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Which is fascinating because it means evolution wasn't following a single blueprint.
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Different populations encountered similar environmental pressures and independently developed their own solutions.
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The destination was similar, the road was different, and that's something evolution does all the time.
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Nature is surprisingly creative, sometimes almost suspiciously creative, like it's showing off.
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What about everyone in between?
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Here's where popular discussions often fall apart.
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People tend to imagine human skin color as three neat categories.
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Black, white, Asian.
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Simple, clean, easy to remember.
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Also completely wrong.
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Human pigmentation exists on a spectrum.
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A massive spectrum.
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As humans spread across the planet, local environments created different selective pressures.
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Some regions had intense UV radiation.
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Some had moderate levels.
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Some had seasonal variation.
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Some populations mixed repeatedly over thousands of years.
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The result wasn't three colors.
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The result was hundreds, maybe thousands, a gradual continuum stretching across continents.
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North Africans developed different pigmentation patterns than West Africans.
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Middle Eastern populations developed different patterns than Europeans.
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South Asians developed different patterns than East Asians.
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Indigenous Australians followed their own evolutionary path.
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Native Americans inherited traits from populations that migrated through Asia long before written history existed.
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Humanity didn't divide into a few neat boxes.
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It diversified, continuously, messily, exactly the way evolution tends to do everything.
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The race illusion.
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Here's the truly strange part.
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If you traveled back far enough, every human alive today would eventually trace their ancestry back to the same African populations.
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Every single one.
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The person with the darkest skin.
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The person with the lightest skin.
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The blonde Scandinavian.
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The Nigerian athlete athlete, the Korean engineer, the Peruvian farmer, go back far enough and their family trees begin merging.
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Eventually, the branches become the same trunk, which means something many people find surprisingly difficult to process.
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The visible differences between modern human populations are actually quite recent.
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Humanity spent far more time looking relatively similar than looking different.
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The traits we often focus on today represent a tiny fraction of our species' existence.
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A few thousand generations.
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A blink of an eye in evolutionary terms.
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And underneath all those differences, humans remain remarkably similar genetically.
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Far more similar than most people imagine.
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Which brings us back to that person standing in East Africa 200,000 years ago.
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They had no idea Europe existed.
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No idea Asia existed.
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No idea that one day humans would build cities, launch satellites, invent social media,
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and spend hours arguing with strangers online about things neither of them fully understand.
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They were simply trying to survive.
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Yet inside them existed the ancestors of everyone.
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Every nation.
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Every language.
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Every culture.
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Every skin color every face you'll ever see.
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The incredible thing about human pigmentation isn't that we're different.
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It's that we're different in such predictable ways.
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A little more sunlight here, a little less sunlight there.
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Thousands of years pass, genes shift, adaptations spread, and gradually, almost imperceptibly,
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humanity begins pinning itself in new shades.
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Not because we became separate species, not because we stopped being related, but because the same species encountered different worlds.
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So what color were the first humans?
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Almost certainly dark-skinned, but that's only the beginning of the story.
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Because every skin tone on earth today is part of the exact same journey.
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A journey that started under the African sun, long before history, long before civilization,
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and long before anyone had words for the categories we use now.
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The next time you look in the mirror, you're seeing one small variation of an experiment that's been running for hundreds of thousands of years.
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And no matter what shade of skin is looking back at you, the story starts in exactly the same place.
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One species, one origin, one African beginning.
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Everything else came later.
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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「Why do Humans Have Different Skin Colors?」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：skin, evolution, thousand, dark, sunlight。 この動画には、シャドーイング用の文が167文、単語が1533語あります。 音声の長さは12:04です。 話す速さは1分あたり約127語で安定しており、シャドーイングしやすいペースです。 英語の頻出3,000語に含まれる単語は78%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 |
|---|---|---|
| sunlight 名詞 | /ˈsʌnˌlaɪt/ | 日光, 太陽光 |
| vitamin 名詞 | /ˈvɪt.ə.mɪn/ | ビタミン |
| melanin 名詞 | /ˈmɛlənɪn/ | メラニン |
| pigmentation 名詞 | 色素沈着 | |
| trait 名詞 | /tɹeɪt/ | 特徴 |
| surprisingly 副詞 | /səˈpɹaɪzɪŋli/ | 驚くほど, 意外に |
| shade 名詞 | /ʃeɪd/ | 影 |
| ancestor 名詞 | /ˈæn.sɛs.tɚ/ | 先祖, 祖先 |
| ultraviolet 形容詞 | /ˌʌltɹəˈvaɪələt/ | 紫外線の |
| homosexual 形容詞 | /ˌhɒməʊˈsɛksjuːəl/ | 同性愛者 |
| absorb 動詞 | /æbˈsɔɹb/ | 吸収する |
| continent 名詞 | /ˈkɑntɪnənt/ | 大陸 |
| variation 名詞 | /ˌvɛəɹiˈeɪʃn̩/ | 変動, 変化 |
| athlete 名詞 | /ˈæθ.liːt/ | 陸上競技の選手, 陸上選手 |
| farmer 名詞 | /ˈfɑɹ.mɚ/ | 農夫, 農家 |
動画に出てくる句動詞
| 単語 | 意味 |
|---|---|
| go back 動詞 | 戻る, 帰る |
| show off 動詞 | 見えをはる, 見せようとする |
繰り返し練習したい文
動画に出てくる短く完結した文です。日常会話でそのまま使えます。
- Let's start at the beginning, the original human color.
- Did you survive long enough to have children?
- Every skin color every face you'll ever see.
- It's that we're different in such predictable ways.
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 | was populated · being related |
| 関係詞節 who / which + 節 — 人や物について情報を加える | people who would · trunk, which means |
注意したい発音
話し手はwasn't, we're, wouldn'tなど、短縮形や弱形を19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: athlete /ˈæθ.liːt/, thrive /θɹajv/, pathway /ˈpæθˌweɪ/, underneath /ˌʌndɚˈniθ/, mathematics /mæθ(.ə)ˈmæt.ɪks/
- 「sh」と「zh」の音: evolutionary /ˌiː.vəˈluː.ʃən.ɛɹ.i/, shade /ʃeɪd/, adaptation /ˌæd.æpˈteɪ.ʃən/, variation /ˌvɛəɹiˈeɪʃn̩/, nutshell /ˈnʌt.ʃɛl/
- 長い単語（アクセントの位置に注意）: evolutionary /ˌiː.vəˈluː.ʃən.ɛɹ.i/, surprisingly /səˈpɹaɪzɪŋli/, ultraviolet /ˌʌltɹəˈvaɪələt/, homosexual /ˌhɒməʊˈsɛksjuːəl/, adaptation /ˌæd.æpˈteɪ.ʃən/
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: evolutionary /ˌiː.vəˈluː.ʃən.ɛɹ.i/, surprisingly /səˈpɹaɪzɪŋli/, ultraviolet /ˌʌltɹəˈvaɪələt/, blueprint /ˈbluːˌpɹɪnt/, equatorial /ˌɛkwəˈtɔːɹiəl/
- /v/ — /b/ にならないように、上の歯を下唇に当てる: evolutionary /ˌiː.vəˈluː.ʃən.ɛɹ.i/, vitamin /ˈvɪt.ə.mɪn/, ultraviolet /ˌʌltɹəˈvaɪələt/, evolve /ɪˈvɑlv/, variation /ˌvɛəɹiˈeɪʃn̩/
- /f/ — 「フ」ではなく、上の歯と下唇で出す: farmer /ˈfɑɹ.mɚ/, diversify /daɪˈvɝ.sə.faɪ/, fascinate /ˈfæsɪneɪt/, unfold /ʌnˈfoʊld/, philosopher /fəˈlɑsəfɚ/
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。
- 通常の速度で一文ずつシャドーイングし、話し手のリズムに合うまで繰り返します。
- 自分の声を録音して元の音声と比べます。sunlight, vitamin, melanin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。