科學家發現地球最古老化石 迄今已有37億年

Scientists have found what they think is the oldest fossil on Earth, a remnant of life from 3.7 billion years ago when Earth's skies were orange and its oceans green.

近日，科學家發現了距今約37億年前的微生物菌席化石，當時地球天空還是橘色的，大海也還是綠色的。他們認爲這是迄今爲止發現的最古老的化石。

In a newly melted part of Greenland, Australian scientists found the leftover structure from a community of microbes that lived on an ancient seafloor, according to a study in Wednesday's journal Nature.

《自然》雜誌週三刊登的文章報道，澳大利亞的科學家在格林蘭島一塊新融化的區域發現孕育於古代海牀的微生物菌席化石。

The discovery shows life may have formed quicker and easier than once thought, about half a billion years after Earth formed. And that may also give hope for life forming elsewhere, such as Mars, said study co-author Martin VanKranendonk of the University of New South Wales and director of the Australian Center for Astrobiology.

該報告的聯合作者、也是新南威爾士大學學者和澳大利亞地球科學研究中心負責人的馬丁·範克朗多克表示，該發現說明地球生命形成的時間要比預想的早而且容易，大概在地球形成5億年就形成了。該發現也可能證實火星等其他星球也許也存在生命。

"It gives us an idea how our planet evolved and how life gained a foothold," VanKranendonk said.

範克朗多克說道："這一發現有助於我們理解地球的演化，以及地球生命是如何孕育的。"

Scientists had thought it would take at least half a billion years for life to form after the molten Earth started to cool a bit, but this shows it could have happened quicker.

地球早期火山噴發不斷，內部溫度很高。科學家們此前一直認爲生命體是在地球溫度稍微變冷的時候出現的，但是現在如果該發現屬實的話則意味生命體開始形成的時間要更早。

That's because the newly found fossil is far too complex to have developed soon after the planet's first life forms.

因爲這些新發現的化石很複雜，不可能在地球上出現生命體不久就形成。

In an outcrop of rocks that used to be covered with ice and snow which melted after an exceptionally warm spring, the Australian team found stromatolites, which are intricately layered microscopic layered structures that are often produced by a community of microbes.

來自澳大利亞的科學小組無意中在凸起的岩石中發現了疊層石，疊層石是由微生物羣構成的沉積結構。這些岩石此前被冰雪覆蓋，由於極度暖和的春天，冰雪融化，它們才得以"重見天日"。

The stromatolites were about 1 to 4 centimeters high.

這些疊層岩介於1-4公分之間。

It "is like the house left behind made by the microbes," VanKranendonk said.

範克朗多克說道："它就像是微生物們留下的空房子"。

The dating seems about right, said Abigail Allwood, a NASA astrobiologist who found the previous oldest fossil, from 3.48 billion years ago, in Australia.

美國航空航天局的地質學家阿比蓋爾·奧爾伍德對此提出了自己的質疑，她此前曾於澳大利亞發現了34.8億年前的化石。

But Allwood said she is not completely convinced that what VanKranendonk's team found once was alive. She said the evidence wasn't conclusive enough that it was life and not a geologic quirk.

但是奧爾伍德還表示，這一時間推論看起來沒什麼問題，該團隊的發現並不能完全說服自己。她認爲本次發現的證據還不足以證明他們發現是生命體而非地理學上的巧合。

"It would be nice to have more evidence, but in these rocks that's a lot to ask," Allwood said in an email.

奧爾伍德在一封郵件中寫到："能發現更多的證據當然很棒，但是目前發現的這些岩石中還存在很多謎團。"