VOA科学技术2023 中国地质大学研究解释生命如何捱过雪球地球时期（在线收听）

Life on Earth faced an extreme test of survivability during the Cryogenian Period, which began 720 million years ago. The planet was frozen over most of the 85 million-year period.

在始于7.2亿年前的成冰纪，地球上的生命面临着生存能力的极端考虑。地球在这8500万年里，大部分时间都处于冰冻状态。

Scientists say Earth would have looked like a shiny white snowball in space during the deep freeze.

科学家表示，在这段深度冰冻期间，地球看起来就像是太空中的一个闪亮的白色雪球。

But life somehow survived during this time called "Snowball Earth." A recent study offers a deeper understanding as to why.

但是不知何故，生命在这个被称为“雪球地球”的时代幸存了下来。最近的一项研究对其原因提供了更深入的解释。

Fossils identified as seaweed were found in black shale, a kind of rock, in central China's Hubei Province. The scientists said the fossils are a sign that livable water environments were more widespread at the time than they once believed.

在中国中部省份湖北省的黑色页岩中发现了被鉴定为海藻的化石。科学家们表示，这些化石表明，当时宜居的水环境比他们曾经认为的要更为广泛。

Nature Communications published the research this month.

《自然·通讯》杂志本月发表了这项研究。

The findings support the idea that the planet was more of a "Slushball Earth" with melting snow. This enabled the earliest forms of complex life to survive in areas once thought to have been frozen solid.

这些发现支持了这样一种观点，即地球更像是一颗有融雪的“泥泞地球”。这使得最早形式的复杂生命体能够在曾被认为冰封的区域存活下来。

The fossils date from the second of the two times during the Cryogenian Period when ice sheets stretched from the poles toward the equator. This period, called the Marinoan Ice Age, lasted from about 651 million to 635 million years ago.

这些化石可以追溯到两次成冰纪中的第二次，当时冰盖从两极向赤道延伸。这一时期被称为马里诺冰河时期，持续时间从大约6.51亿年到6.35亿年前。

Huyue Song of the China University of Geosciences was the study's lead investigator and writer. The researcher said the most important finding was that ice-free, open water conditions existed in place during the last part of the Marinoan Ice Age.

中国地质大学的宋虎跃是这项研究的首席研究员和作者。这位研究人员表示，马里诺冰河时期存在着无冰的开放水域环境，这是最重要的发现。

"More extensive areas of habitable oceans better explain where and how complex organisms such as multicellular seaweed survived," Song said.

宋虎跃表示：“更广泛的海洋宜居区域可以更好地解释多细胞海藻等复杂生物在什么地方，以及如何生存。”

The findings demonstrate that the world's oceans were not completely frozen. It means areas of habitable refuge existed where multicellular organisms could survive, the scientist added.

研究结果表明，全球海洋并未完全冻结。科学家补充说，这意味着存在多细胞生物可以生存的宜居避难之所。

Earth formed about 4.5 billion years ago. The first single-celled organisms appeared in the first billion years of the planet's existence. Multicellular organisms arrived later, maybe two billion years ago. But it was only after the Cryogenian period that warmer conditions returned. That helped drive a quick expansion of different life forms about 540 million years ago.

地球大约形成于45亿年前。第一批单细胞生物出现在地球存在的前十亿年。多细胞生物出现的时间较晚，可能在20亿年前。但直到成冰纪之后，温暖的天气才回归。这推动了不同生命形式在大约5.4亿年前快速扩张。

Scientists are trying to better understand the start of "Snowball Earth." They believe a greatly reduced amount of the sun's warmth reached the planet's surface as its radiation bounced off the white ice sheets.

科学家们正试图更好地理解雪球地球的起源。他们认为，当太阳辐射从白色冰盖反射时，到达地球表面的热量大大减少。

Seaweed and fossils of some other multicellular organisms were identified in the black shale. This seaweed was a photosynthetic organism living on the seafloor in a shallow sea environment lit by sunlight.

在黑色页岩中发现了海藻和其它多细胞生物的化石。这种海藻是一种光合生物，生活在阳光照射的浅海环境的海底。

"The fossils were preserved as compressed sheets of organic carbon," said researcher Qin Ye, also of China University of Geosciences.

同样来自中国地质大学的研究员叶琴表示：“这些化石是以压缩的有机碳片的形式保存下来的。”

Multicellular organisms including red algae, green algae and fungi appeared before the Cryogenian and survived "Snowball Earth."

包括红藻、绿藻和真菌在内的多细胞生物出现在成冰纪之前，并在雪球地球时期幸存下来。

The Cryogenian freeze was much worse than the most recent Ice Age that humans survived. It ended about 10,000 years ago.

成冰纪的冰冻比人类幸存下来的最近一次冰河时代要严重得多。冰河时期大约于一万年前结束。