Researchers say the Earth had much more oxygen nearly a billion years ago than scientific experts thought. That claim could change theories about how life developed on our planet.
研究人员表示，近10亿年地球上存在的氧气比科学家们所料想的要高出很多，这种说法可能会改变地球生命起源的理论。
The claim came from researchers at Brock University in Canada. They wanted to measure the levels of oxygen in the Earth's atmosphere nearly a billion years ago. To do this, the researchers developed a way to study small air bubbles trapped in ancient salt crystals.
这种说法出自于加拿大布鲁克大学的研究人员。他们想要测量近10亿年前地球大气层的氧含量。为了实现这点，这些研究人员开发了一种办法来研究夹带在古盐结晶中的小气泡。
"There was a lot of debate as to what the oxygen content was 800 million or more years ago," said Nigel Blamey of Brock University's Department of Earth Sciences. He said the trapped gasses showed that the oxygen level was about half of what it is today.
布鲁克大学地球科学系的奈杰尔·布兰梅（Nigel Blamey）表示，“关于8到10亿年前的氧含量存在很多争议。”他说，这些夹带的气体表明当时的氧含量是现在的一半左右。
In fact, many experts believed that the oxygen level was only about two percent of the atmosphere so long ago. But the new study found that it was almost 11 percent. Currently, oxygen is about 21 percent of the atmosphere.
事实上，很多专家认为那么久远之前的氧含量大约只占到大气的2%。但是这项新的研究发现它将近为11%。目前大气中的氧气含量大约是21%。
The Canadian researchers used a method to study air bubbles trapped in halite, the natural form of table salt.
这些加拿大研究人员利用一种办法来研究岩盐中夹带的气泡。岩盐是食盐的自然形态。
The researchers say their findings have major effects for theories about how and when life developed.
研究人员表示，他们的发现对生命何时以及如何发展的理论具有重大影响。
Professor of Earth Sciences Uwe Brand said that higher oxygen levels in the past may turn back the clock when complex life developed. "Now paleobiologists will have reason to go looking for rocks with" evidence of these first evolutionary steps," he told the Canadian Broadcasting Corporation.
地球科学系教授乌韦·布兰恩德（Uwe Brand）表示，过去的氧含量更高可以让复杂生命起源的时间提前。他对加拿大广播公司表示，“现在古生物学家将有理由去岩石中寻找进化第一步的证据。”
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