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  • [Life will not be contained. Life breaks free. | - Dr. Ian Malcolm in Jurassic Park. Dir. Steven Spielberg]

    [生命是不受限制的。生命會突破重圍。| -伊恩·馬康姆博士,《侏儸紀公園》,由史蒂芬·史匹柏格導演]

  • Billions of years ago, on the young planet Earth, simple organic compounds assembled into more complex coalitions that could grow and reproduce.

    數十億年前,在年輕的地球上,簡單的有機化合物組合成了能夠成長及繁殖,更複雜的結合體。

  • They were the very first life on Earth, and they gave rise to every one of the billions of species that have inhabited our planet since.

    它們是地球上最早的生命,自此之後,地球上出現的數十億種物種通通都起源於它們。

  • At the time, Earth was almost completely devoid of what we’d recognize as a suitable environment for living things.

    在當時,地球上可說是非常缺乏我們現今認為適合生物的環境。

  • The young planet had widespread volcanic activity and an atmosphere that created hostile conditions.

    在這顆年輕的星球上到處都是火山活動,當時的大氣條件對生物也並不友善。

  • So where on Earth could life begin?

    所以,生命究竟起源於地球上的何處?

  • To begin the search for the cradle of life, it’s important to first understand the basic necessities for any life form.

    若要開始尋找生命起源的搖籃,最重要的是先要了解各種生命形式有什麼基本需求。

  • Elements and compounds essential to life include hydrogen, methane, nitrogen, carbon dioxide, phosphates, and ammonia.

    對生命來說必備的元素和化合物包括:氫、甲烷、氮、二氧化碳、磷酸鹽和氨。

  • In order for these ingredients to comingle and react with each other, they need a liquid solvent: water.

    而這些要素彼此之間若要能混合並產生化學變化,就需要有液體的溶媒:水。

  • And in order to grow and reproduce, all life needs a source of energy.

    而所有的生命若要成長和繁殖,便會需要能量來源。

  • Life forms are divided into two camps: autotrophs, like plants, that generate their own energy, and heterotrophs, like animals, that consume other organisms for energy.

    生命形式可以分成兩大類:自營生物,如植物,會產生自己要用的能量,以及異營生物,如動物,要食用其他有機體來取得能量。

  • The first life form wouldn’t have had other organisms to consume, of course, so it must have been an autotroph, generating energy either from the sun or from chemical gradients.

    當然,最早的生命形式不會有其他有機體可供其食用,所以它們一定得是自營生物,從太陽或化學梯度中獲取能量。

  • So what locations meet these criteria?

    那麼有什麼地點能夠符合這些條件呢?

  • Places on land or close to the surface of the ocean have the advantage of access to sunlight.

    地面上或海洋中接近表面的地方比較有取得陽光的優勢。

  • But at the time when life began, the UV radiation on Earth’s surface was likely too harsh for life to survive there.

    但在生命剛出現時,地球表面上的紫外線很可能太過嚴酷,讓生命無法存活下來。

  • One setting offers protection from this radiation and an alternative energy source: the hydrothermal vents that wind across the ocean floor, covered by kilometers of seawater and bathed in complete darkness.

    而有一種環境能在提供保護阻擋紫外線的同時,也具有替代的能量來源:那就是在海底蜿延的海底熱泉區。它們被數公里的海水覆蓋,完全處於黑暗之中。

  • A hydrothermal vent is a fissure in the Earth’s crust where seawater seeps into magma chambers and is ejected back out at high temperatures, along with a rich slurry of minerals and simple chemical compounds.

    深海熱泉區是地球地殼上的裂縫,而海水會從該處滲入岩漿庫中,接著以高溫被重新噴射出來,附帶著富含礦物質及簡單化合物的泥漿。

  • Energy is particularly concentrated at the steep chemical gradients of hydrothermal vents.

    深海熱泉區的陡峭化學梯度有著格外集中的能量。

  • There’s another line of evidence that points to hydrothermal vents: the Last Universal Common Ancestor of life, or LUCA for short.

    還有其他證據證明深海熱泉區是生命起源:生命的最後共同祖先(LUCA)。

  • LUCA wasn’t the first life form, but it’s as far back as we can trace.

    LUCA 並非是最早的生命形式,但它是我們所能追溯到的最古老生物。

  • Even so, we don’t actually know what LUCA looked likethere’s no LUCA fossil, no modern-day LUCA still around.

    即便如此,我們其實不知道 LUCA 長成什麼樣子——我們尚未尋獲 LUCA 化石, 也沒有 LCUA 存活到現在。

  • Instead, scientists identified genes that are commonly found in species across all three domains of life that exist today.

    不過科學家們發現,在現今仍然存在的三大生命領域物種中有著部份共同的基因。

  • Since these genes are shared across species and domains, they must have been inherited from a common ancestor.

    由於這些基因存在於不同的物種和領域,因此它們一定是來自共同的祖先。

  • These shared genes tell us that LUCA lived in a hot, oxygen-free place and harvested energy from a chemical gradientlike the ones at hydrothermal vents.

    這些共同基因告訴我們 LUCA 住在一個很熱、沒有氧氣的地方,並從化學梯度取得能量,而深海熱泉區正好符合。

  • There are two kinds of hydrothermal vent: black smokers and white smokers.

    深海熱泉區分為兩種:黑煙囪和白煙囪。

  • Black smokers release acidic, carbon-dioxide-rich water, heated to hundreds of degrees Celsius and packed with sulfur, iron, copper, and other metals essential to life.

    黑煙囪會釋放富含二氧化碳的酸性水,溫度高達攝氏數百度,且滿是硫磺、鐵、銅,以及其他對生命至關重大的金屬。

  • But scientists now believe that black smokers were too hot for LUCAso now the top candidates for the cradle of life are white smokers.

    但現在科學家相信,對 LUCA 而言黑煙囪太熱了,因此白煙囪才最有可能是生命起源的搖籃。

  • Among the white smokers, a field of hydrothermal vents on the Mid-Atlantic Ridge called Lost City has become the most favored candidate for the cradle of life.

    而在散佈各處的白煙囪當中,大西洋中洋脊中一塊被稱為「失落之呈」的深海熱泉區被認為最有可能是生命起源的搖籃。

  • The seawater expelled here is highly alkaline and lacks carbon dioxide, but is rich in methane and offers more hospitable temperatures.

    這裡噴出的海水為強鹼性且缺乏二氧化碳,但其中富含甲烷,溫度也比較適宜。

  • Adjacent black smokers may have contributed the carbon dioxide necessary for life to evolve at Lost City,

    周遭的黑煙囪則可能為在「失落之城」中進化的生命體提供了二氧化碳,

  • giving it all the components to support the first organisms that radiated into the incredible diversity of life on Earth today.

    給予了進化至現今在地球上有著令人歎為觀止的各式物種的第一種生物所需的全部元素。

  • Did you know that a single-celled organism caused the first mass extinction? Check out this animation about how it almost wiped out life on earth, and paved the way for complex life.

    你知道曾經有一種單細胞生物體造成了首次的大滅絕嗎?現在就來看看這個動畫,了解它是如何幾乎滅絕了地球上所有的生命,並且為更複雜生命體的演化鋪路吧。

[Life will not be contained. Life breaks free. | - Dr. Ian Malcolm in Jurassic Park. Dir. Steven Spielberg]

[生命是不受限制的。生命會突破重圍。| -伊恩·馬康姆博士,《侏儸紀公園》,由史蒂芬·史匹柏格導演]

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B2 中高級 中文 美國腔 TED-Ed 生命 深海 地球 能量 二氧化碳

大自然的奧妙!地球上生命的起源是什麼?!(The mysterious origins of life on Earth - Luka Seamus Wright)

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    林宜悉 發佈於 2021 年 10 月 20 日
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