為何加發現37.7億年前化石 或預示火星曾有生命？

今天看到一則新聞《加發現37.7億年前化石 或預示火星曾有生命》，裡面也沒有具體說明。為何地球發現化石，會預示火星有生命呢？

疑似的微生物化石被發現在魁北克一套石英岩（quartz layers？）中，附近見到了地球上最古老的沉積岩曾經，發現者認為這可能是由海底熱泉產生的生物，

懷疑者認為，這可能是由於地層後期溫壓改變，後期的生物作用或非生物作用形成。該研究第一作者也發現，微化石具有新生物（後期生物）的特徵，但還沒獲得遺傳信息，不過他還是堅信這是非氧化細菌。

如果屬實，那就是在42.5億年就出現了生物。

反正不少人覺得那根本就不是生物，還有人覺得是外星球生物

報道末宕開一筆：這些生物存在的條件十分簡單，如水、火山活動和常見元素如碳存在即可，這點條件火星很可能就滿足

話說那把鎚子真不錯，好想有一把，看到鎚子就很親切。

找到國外的兩篇報道：

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報道1：CNN 報道：

Worldamp;amp;amp;#x27;s oldest microfossils found, study says

原文：

(CNN)Scientists claim to have discovered the remains of microorganisms in Canada that are at least 3.77 billion years old. If they are proven to have a biological origin, they would be the oldest microfossils ever found.

The discovery comprises tiny filaments and tubes formed by bacteria that lived on iron, according to a statement released Wednesday by University College London.

They were found in quartz layers in the Nuvvuagittuq Supracrustal Belt in Quebec, Canada, which contains some of the Earth"s oldest known sedimentary rocks, it said.

Ancient fossils have been found on the Nuvvuagittuq Supracrustal Belt in Quebec, Canada.

"Our discovery supports the idea that life emerged from hot, seafloor vents shortly after planet Earth formed," said Matthew Dodd, a researcher at UCL Earth Sciences and the London Center for Nanotechnology and one of the report"s authors.

Oldest life forms?

The oldest microfossils previously reported were found in Western Australia in 2013 and dated to around 3.4 billion years ago.

But questions have been raised over the credibility of those finds. Some suggested that what appeared to be fossils could have been formed by biological or non-biological processes, such as temperature or pressure changes in the rocks over millions of years.

The team of international scientists working in Canada said its discovery had clear signs of being biological in origin, including minerals "found in biological matter including bones and teeth," according to a statement from UCL.

"The microfossils we discovered have a range of traits that are similar to younger biological fossils," the study"s lead author, Dominic Papineau, told CNN. "They have a twisted structure, a little bit like a corkscrew, and branching filaments. We don"t have the genetic information yet, but we believe they are non-oxidizing bacteria."

Orange-colored iron carbonite may once have been part of a hydrothermal vent miles underwater

According to Papineau, these microorganisms, which could breathe and eat, could be up to 4.28 billion years old. "If they are this old, this means that life developed very rapidly on Earth," Papineau said. "Just 250 million years after the Earth formed, life was already quite complex."

Not all scientists are convinced by the team"s findings, however.

William Martin, head of the Molecular Evolution Institute at Dusseldorf"s Heinrich Heine University, told CNN he is "unconvinced that this is biological material. There is no clear cut evidence that these were made by biology. It"s not good enough that these things look like cells."

Papineau hopes that the team"s findings will eventually be accepted by the whole scientific community. "We have been very specific with our nine independent lines of evidence," he told CNN. With this research, he added, "we have certainly documented evidence of early life better than anyone else."

Extraterrestrial life

As well as potentially shedding light on Earth"s earliest life forms, the discovery could have implications for the search for life beyond our planet.

"If it happened very quickly here," Papineau told CNN, "it could have happened elsewhere in the solar system."

According to Papineau, the development of these life forms requires only water, volcanic activity and the presence of common chemicals such as carbon. These organisms could have developed at a similar time on Mars or the moons of Jupiter and Saturn, Papineau said.

If any signs of such life forms are detected, however, don"t expect them to appear familiar.

One of our earliest ancestors ever discovered, Saccorhytus, from a category of creatures called deuterostomes dating from around half a billion years ago -- far, far more recent than the Canadian find -- looks more like something from "Alien" than anything seen on Earth today.

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報道2：Do the Quebec fossils prove that life begin much earlier than we thought?

What』s all the excitement about?

A team of scientists say they have discovered the oldest fossils on Earth in rocks from Quebec. Dating techniques suggest the rocks are at least 3.8bn years old, and might even be 4.3bn years old.測年技術確定至少是在38億年前，最早可到43億年

What do these fossils look like?

They are tiny. They consist of filaments and tubes up to half a millimetre in length and around half the width of a human hair. They』re made of haematite, a type of iron oxide (better known as rust). Some of the filaments resemble loose coils, some are branched, and others appear to be joined to knobs of haematite. The tubes and filaments are thought to be the remains of bacteria that lived on iron and dwelt around hydrothermal vent systems – mineral-rich hot springs – on the seafloor. Similar systems have been proposed as a likely location for where life first arose.由赤鐵礦組成，0.5mm長，髮絲一般粗細，生活在海底富礦物質熱泉附近

How do we know the bacteria lived underwater?

Telltale chemical signatures, and distinctive structures such as pillow-shaped masses, point to an underwater formation for the rocks. The fossils themselves were discovered in a type of iron-rich quartz known as jasper. This jasper was found between volcanic rocks, and probably formed as material ejected from hydrothermal vents settled.化石發現在富鐵石英（碧玉）中，碧玉多發現在火山中，這也佐證了熱泉模式

How do we know these tubes and filaments are fossils?

That』s the tricky bit. The authors of the study say they are confident for several reasons. They argue that the haematite structures are similar to those produced by iron-oxidising bacteria today, as well as to microfossils found in younger rocks, hundreds of millions – rather than billions – of years old. What』s more, the structures were found to contain graphite as well as the minerals apatite and carbonate – which are associated with biological matter. Finally, the team found iron-oxide granules and, in other sections of the rocks, structures such as carbonate rosettes (also associated with apatite, graphite and carbonate), which, they say, could have formed as biological matter broke down.

有人認為那種赤鐵礦的結構跟現代鐵-氧化細菌作用結果相似，這種細菌是在數百萬年來活動的，而不是數十億年前的；同時這種赤鐵礦結構在生物成因的碳酸鹽岩和磷灰石里也見到過。不過發現者通過一些證據說，上面正是有機物質後期的分解才造成上面這些混淆

Does everyone agree?

No. While the researchers say their investigation ruled out the chance that the structures were formed by geological processes, others are not convinced. The rocks in which the fossils were found are metamorphic, meaning that they have experienced high temperatures and pressures since they formed – some argue that this could have produced the structures instead. The size and arrangement of the haematite structures has also raised concerns, as has the fact that the microbes would have relied on oxygen at a time oxygen is thought to have been scarce. .發現疑似化石的岩石是經過高溫高壓作用的變質岩，這種高溫高壓作用可以完全破壞掉化石的生物結構，一般這種岩石裡面發現化石几乎不可能的（後期微生物存在也可能）；這種疑似生物的赤鐵礦結構，其尺度和排列也值得懷疑，幾十億年前那種缺氧環境真的能存在依賴氧氣存活的生物嗎

How does this fit in with other ancient fossil finds?

The previous 「oldest fossils」 date to about 3.5bn years ago and were found in Western Australia. However, they have been the subject of hot debate, with many experts unconvinced they are the remains of microbes. Another finding was reported last year, with researchers claiming that they had found fossil traces of microbial activity, known as stromatolites, in rocks from Greenland dating to 3.7bn years ago – 220m years older than the previous oldest known stromatolites. Again, experts were split on whether the evidence was strong enough to suggest the structures were made by organisms, rather than through geological processes. Other younger and better-preserved finds are less contentious.

目前最早的化石一個是35億年前在澳大利亞西部發現啊的，另一個是格陵蘭37億年前的。下一步就是要找到充分足夠的證據

What does this tell us about early life on Earth?

If the structures are microfossils, the discovery shows that fairly sophisticated microbes might have been around as early as 4.3bn years ago, pushing back the origins of life on Earth to, potentially, 4.4bn years ago. With planet Earth only 4.5bn years old, that suggests life got going and diversified pretty quickly. That raises the possibility that life can crop up rapidly when the right conditions are present.如果這一發現得到認可，地球生命最早就會出現在43億年，就是說地球形成才過了2億年，就出現生命了

What does this mean for the search for life 「out there」?

We know that, in its early beginnings, Mars, like Earth, had oceans. If these newly discovered structures are fossils, it raises the possibility that microbes were also thriving on Mars – and offers clues as to what scientists should be looking for in rocks on the red planet. The find also supports the idea that other bodies in the solar system, such as Jupiter』s moon Europa, might be good places to look for life, since it has been proposed that Europa might have hydrothermal vents under its icy shell.

科學家模擬的四十億年前火星的地貌，當時火星還擁有磁場，後來因為 隕石撞擊火星，形成巨大的海拉斯盆地造成磁場消磁，太陽風將火星大氣層吹散造成火星現在的模樣，如果這個理論成立，那麼從之前ALH84001火星隕石（正好產生於40億年前，並於 1.5億年 前再次遭受撞擊離開火星 到達地球）上發現的生命化石表面地球和火星的生命是同文同祖的，甚至就是來自火星的，畢竟40億年前火星遭受撞擊後肯定有大量隕石落在地球，因為地球和火星形成時間相近，初階段歷史相似，如果地球的 冥古代 都有生命的話，那麼比地球更古老的火星也有生命也不足為奇了。