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Earth’s Oldest Fossils Could Provide Clues to Life on Other Planets 地球上最古老的化石可能提供外星生命的线索

August 23, 2011

Origin from VOA 原文来自VOA

原文网址:http://blogs.voanews.com/science-world/2011/08/22/earths-oldest-fossils-could-provide-clues-to-life-on-other-planets/

翻译:George Lam

Researchers from England and Australia recently found some microfossils in a remote part of Western Australia.

澳大利亚和英国的研究人员最近在澳大利亚西部的偏远地区发现一些微化石。

Before you click away and say, “Big deal another fossil find,” hang with me for a bit.

在你想离开并说“有什么大不了啊?发现化石而已。”之前,请等一等。

The microscopic fossils, according to the researchers, are 3.4 billion years old, making them Earth’s oldest fossils.

根据研究人员所说,这些极微小的化石有三十四亿岁了,是地球上最古老的化石。

The fossils resulted from life forms which lived on our planet before Earth even had oxygen.

化石产生自生物,而这些生物是生活在没有氧气时候的地球。

Wow!  Kind of hard to visualize Earth without its life-giving oxygen, isn’t it?

哇!很难想象地球上没有氧气啊,不是吗?

OK, lets step back to the time when Earth first formed.

好的,让我们追溯到地球刚形成的时期。

Most scientists generally agree that our planet is between 4.5 and 4.6 billion years old.

大多数科学家大概认同我们的星球大概形成于45~46亿年前。

Soon after being formed, Earth was a huge molten hunk of rock with no atmosphere and, of course, none of the characteristics that make our planet special.

在刚刚形成的时候,地球是一个没有大气层的巨大的熔融的岩石块。当然没有一个特征让我们的星球与众不同。

At this time, Earth’s core was also still forming. There was no solid inner core or  liquid outer core, like there is today, so the world wasn’t able to retain gasses very well.

这个时候,地球核心还在形成中。还没有固态内核,也没有液态外核,跟今天的不一样,所以那时候地球不能很好地保持住气体。

Scientists describe our first atmosphere as being composed of hydrogen and helium, two elements which were very common when Earth and the rest of the solar system were formed.

Because of the heat and unformed core, these gasses soon escaped from Earth into space.

科学家把我们的第一大气层描述为氢气和氦气的组成,这两种元素在地球和太阳系的其他星球形成时是非常普遍的。因为热和未形成的核心,这些气体很快地从地球跑到太空。

Earth continued its cooling process and, as the core began to stabilize, the earth’s magnetic fields were formed.

因为核心开始稳定下来,地球的磁场也形成了,地球进入了冷却过程。

A more stable core and a cooler planet meant that more of the gasses produced by our evolving world could be retained closer to its surface.

一个更稳定的核心和更冷的星球意味着,更多由我们演进中的世界制造的气体可以被维持在更接近地球表面的地方。

As volcanic activity began and continued to increase throughout the planet, a lot of different gases formed as a result.

因为火山活动开始并且在整个星球上持续增加,形成了大量的不同的气体。

These included carbon dioxide (CO2), carbon monoxide (CO), sulfur dioxide (S2), chlorine (CL2), nitrogen (N2), deuterium, also called heavy hydrogen (H2), ammonia (NH3) and methane (CH4).

这些气体包括二氧化碳、一氧化碳、二氧化硫、氯气、氮气、氘(也叫重氢)、氨和甲烷。

The volcanoes also produced a lot of steam (water/H2O), but no free existing oxygen (O2).

火山同样会制造大量的蒸汽(水/H2O),但没有自由存在的氧气。

Oxygen was later produced and introduced into our atmosphere through two processes; photochemical dissociation, caused by the breakup of water molecules by the sun’s ultraviolet light, and photosynthesis, the process that uses carbon dioxide and water (H2O) to form organic compounds while also releasing oxygen (O2).

氧气是在之后通过两个过程产生并进入到我们的大气层:一个是光化离解,由太阳紫外光将水分子分离而引起;另一个是光合作用,在利用二氧化碳和水形成有机化合物的同时释放出氧气。

Early forms of life that developed and lived during this “pre-oxygen time”, some 3.4 billion years ago, were sulfur-based cells and bacteria which lived off metabolized compounds which had sulfur, rather than oxygen, for energy and growth.

34亿年前,在这个“前氧气时代”发展和生存的早期生命的形式是依赖于有硫而不是氧气的代谢化合物来得到能量和成长的基于硫的细胞和细菌。

The researchers, from the University of Western Australia and England’s  Oxford University,  say their discovery of these microfossils provides convincing evidence that these unique early life forms did exist.

西澳大学和英国牛津大学的研究人员称,他们发现的这些微化石提供了有说服力的证据,证明这些独一无二的早期生命形式是存在的。

Oxford Professor Martin Brasier, one of the team’s leaders, says the life forms of the fossils still exist and are common today.

团队领导之一、牛津大学教授Martin Brasier说,这些化石的生命形式今天依然普遍存在。

The sulfur-based bacteria can be found in smelly ditches, soil, hot springs, hydrothermal vents – anywhere there’s little free oxygen and they can live off organic matter.

基于硫的细菌可以在恶臭难闻的沟渠、土壤、温泉、(海底)热液口等所有缺少自由氧的地方找到,它们依赖有机物质生存。

Professor Brasier says their discovery also has implications in the search for life on other planets, giving scientists an indication of what evidence for such life might look like.

教授Brasier说,他们的发现对于在其他星球上寻找生命是有帮助的,给了科学家一个明示,这样的生命可能是这个样子的(可以往这个方向寻找生命迹象)。

A report on this finding can be found in the journal Nature Geoscience.

在Nature Geoscience杂志上有一篇关于这个发现的报道。

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