Scientists find life may have existed 3.8 BILLION years ago
科學家發現一種有 38 億年歷史的古老生物


The microscopic filaments and tubes, composed of an iron oxide called hematite, appeared within a rock type called jasper.

在顯微鏡下呈現的細絲和管狀物由一種稱為赤鐵礦( hematite )的氧化鐵組成,與一種稱為碧玉 ( jasper ) 的石頭一起出現。

A group of researchers says life on Earth begun much sooner after discovering 3.8 billion-year-old microbes.
Scientists have revealed the EARLIEST life on our planet: the 3.8 billion-year-old microbes have changed a lot about life on Earth, and offer hopes of finding life on other planets like Mars.

一組研究人員團隊表示,這些有 38 億年歷史的微生物被發現之後,我們所知的地球生命起源時間被提早很多。科學家已經揭露地球上最早的生命: 38 億年前的古老微生物讓我們對地球生命的看法改變很多,同時也讓我們覺得有希望能在其他星球上發現生命,例如火星。

According to researchers, life on Earth may have begun much sooner than previously thought. Experts have found evidence of the EARLIEST life ever in 3.8 Billion-year-old fossil microbes in Canada’s ancient sea floor. The discovery of microbes suggests that life could rise from marine hydrothermal sources shortly after the formation of the planet.

根據研究人員的說法,地球上的生命起始時間可能比我們先前所想的要早得多,專家們已經找到證據。有 38 億年歷史的化石微生物是地球上最早出現的生命,它被發現於加拿大的古老海床中。這些微生物的發現顯示,生命可能是從海底熱液系統中興起的,而且在地球形成後不久便興起。

Not long ago, a study published in the prestigious journal Nature.
不久前,一份研究被刊登在權威期刊《自然》 ( Nature )上。

Although it is not known when or where life on Earth began, some of the earliest habitable environments may have been submarine-hydrothermal vents. Here we describe putative fossilized microorganisms that are at least 3,770 million and possibly 4,280 million years old in ferruginous sedimentary rocks, interpreted as seafloor-hydrothermal vent-related precipitates, from the Nuvvuagittuq belt in Quebec, Canada.

雖然我們並不知道地球上的生命是從哪裡、從什麼時候開始出現的,但最早的適居環境應是海底熱泉( hydrothermal vent )。 這被公認的化石微生物至少有三十七億七千萬年的歷史 ,鐵質沉積岩則可能有四十二億八千萬年的歷史,它被認為是與海底熱泉的流瀉相關的沈澱物,來自加拿大魁北克的努夫亞吉圖克地表帶( Nuvvuagittuq belt )。

These structures occur as micrometre-scale haematite tubes and filaments with morphologies and mineral assemblages similar to those of filamentous microorganisms from modern hydrothermal vent precipitates and analogous microfossils in younger rocks. The Nuvvuagittuq rocks contain isotopically light carbon in carbonate and carbonaceous material, which occurs as graphitic inclusions in diagenetic carbonate rosettes, apatite blades intergrown among carbonate rosettes and magnetite–haematite granules, and is associated with carbonate in direct contact with the putative microfossils. Collectively, these observations are consistent with an oxidized biomass and provide evidence for biological activity in submarine-hydrothermal environments more than 3,770 million years ago.

這些組織以微米尺度的赤鐵礦管和細絲的形態存在,它們的形態和礦物組合與那些年輕石頭裡、來自現代海底熱泉沈澱物以及相似微化石的絲狀微生物很類似。努夫亞吉圖克石( Nuvvuagittuq rocks )含有碳酸鹽及含碳物質中的同位素碳光,它在成岩碳酸鹽玫瑰花狀重晶石結合體中,以石墨夾渣( graphitic inclusions )的型態存在 ; 磷灰石葉狀片在碳酸鹽玫瑰花狀重晶石結合體、磁鐵礦( 赤鐵礦顆粒 )中共生,它與碳酸鹽連結,而碳酸鹽則直接與被公認的微化石連結。

總的來說,這些發現與一種氧化生物質一致,並且為三十七億七千萬年前、海底熱液系統環境中的生物活動提供證據。

The microorganism were discovered by an international team of scientists in the so-called Nuvvuagittuq belt, along the eastern shore of Hudson Bay in northern Quebec. Scientists studied tubes and filaments.

這種微生物是由一組國際科學家團隊發現的,發現地在努夫亞吉圖克地表帶,此地表帶位於魁北克省北部的哈得遜灣東部海岸。科學家研究這些管狀物和細絲。

A microscopic image of one of the earliest lifeform ever found CREDIT: DOMINIC PAPINEAU
此圖為顯微鏡下的最早生物形態,這種生物形態是目前所知最古老的。
圖片來源:多米尼克·帕皮諾 DOMINIC PAPINEAU

The new finding not only suggests that life could have arisen and colonized the sea soon after the formation of our planet, but perhaps other worlds—similar to ours—may have had the same characteristics were life may have come into existence.

這個新發現表示生命可能在地球剛形成後不久就已經在海洋中興起並開始移殖,同時也表示那些與我們的世界相似的其他世界可能也有一樣的情形,也就是有相同的生命起始模式。

Scientists say that this discovery also points to the possibility that life—as we know it—may lurk on Mars.
Because the fossils are nearly as old as our planet—Earth formed around 4.5billion years ago—the discovery supports previous studies that life on Earth may have formed in very extreme environments said Matthew Dodd of University College London (UCL), who led the study.
“Modern hydrothermal vent deposits host communities of microorganisms, some of which are iron-oxidising bacteria that form distinctive tubes and filaments,” wrote experts in the study.
“Epifluorescence imaging [microscopes that use fluorescence to generate an image] of modern vent samples has shown that cylindrical casts composed of iron oxyhydroxide are formed by bacterial cells and are undeniably biogenic. Hence, morphologically similar tubes and filaments in ancient jaspers may be taken as biosignatures that can survive elevated temperatures and pressures.”

科學家說,這個發現也指出一個可能性:我們所知的生命形態可能潛藏在火星上。

這些化石幾乎和地球一樣古老( 地球大約在 45 億年前形成 ),所以它們可以支持來自倫敦大學學院 ( UCL ) 的馬修多德( Matthew Dodd )的理論。馬修多德是這個研究的領導人,他先前的研究指出:地球上的生命應是在非常極端的環境中形成的。

進行此研究的專家們寫道:「 現代海底熱泉的沈積物是微生物的寄宿地,有些是氧化鐵菌,這種菌會形成獨特的管狀物和細絲。螢光顯微鏡( Epifluorescence,是一種使用螢光或磷光物質的光學顯微鏡 )拍攝現代熱泉中的樣本,影像中顯示成份為氫氧化鐵的圓柱形管狀物是由細菌細胞組成,並且絕對是生物成因的( biogenic )。因此,那些在古代碧玉中發現的、在形態上相似的管狀物和細絲可以被視為生物標識( biosignatures ),表示可在高溫高壓下存活。」

A section of the rock showing the tiny fossils inside CREDIT: DOMINIC PAPINEAU
石頭的一部份顯示有微小的化石在裡面。
圖片來源: 多米尼克·帕皮諾 DOMINIC PAPINEAU

But perhaps the most important thing is that scientists believe that this discovery gives hopes of finding life on other planets and moons.
Professor Dodd added: “These discoveries demonstrate life developed on Earth at a time when Mars and Earth had liquid water at their surfaces, posing exciting questions for extra-terrestrial life. Therefore, we expect to find evidence for past life on Mars 4,000 million years ago, or if not, Earth may have been a special exception.”
However, there are scientists who remain unconvinced. One such scientist is Roger Buick, a professor in Earth and Space Sciences at the University of Seattle.
“This study seems to have been held to a lower burden of proof than other microfossil reports and fails to meet the standards that would be required for a younger microfossil claim to be accepted. Possible, but not probable, and certainly not persuasive or compelling.”

但,最重要的一件事或許是:科學家們相信,這個發現讓我們覺得在其他星球和月球上有希望發現生命。

多米尼克·帕皮諾教授補充:「 這些發現證明,在火星和地球的表面充滿液態水的時候,生命在地球上開始發展,這使那些令人興奮的外星生命議題顯現出來。因此,我們期待在火星上發現四十億年前的生命證據,如果沒有發現,那就表示地球可能是一個特例。」

然而,依然有科學家沒有被說服。其中一個科學家是 Roger Buick,他是西雅圖大學的地球與太空科學教授。他說:「 這個研究的證據量和其他微化石報告比起來似乎比較少,不符標準,這標準對一個較新的微化石主張來說是必須的,否則難以被接受。這個主張為正確的可能性為百分之五十( Possible ),並不是百分之九十( probable ),並且絕對不具說服力且不令人信服。」

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來源: ancientcode