Study Explains How Life Survived the 'Snowball Earth' Period
2023-04-17
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1Life on Earth faced an extreme test of survivability during the Cryogenian Period, which began 720 million years ago.
2The planet was frozen over most of the 85 million-year period.
3Scientists say Earth would have looked like a shiny white snowball in space during the deep freeze.
4But life somehow survived during this time called "Snowball Earth."
5A recent study offers a deeper understanding as to why.
6Fossils identified as seaweed were found in black shale, a kind of rock, in central China's Hubei Province.
7The scientists said the fossils are a sign that livable water environments were more widespread at the time than they once believed.
8Nature Communications published the research this month.
9The findings support the idea that the planet was more of a "Slushball Earth" with melting snow.
10This enabled the earliest forms of complex life to survive in areas once thought to have been frozen solid.
11The fossils date from the second of the two times during the Cryogenian Period when ice sheets stretched from the poles toward the equator.
12This period, called the Marinoan Ice Age, lasted from about 651 million to 635 million years ago.
13Huyue Song of the China University of Geosciences was the study's lead investigator and writer.
14The 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.
15"More extensive areas of habitable oceans better explain where and how complex organisms such as multicellular seaweed survived," Song said.
16The findings demonstrate that the world's oceans were not completely frozen.
17It means areas of habitable refuge existed where multicellular organisms could survive, the scientist added.
18Earth formed about 4.5 billion years ago.
19The first single-celled organisms appeared in the first billion years of the planet's existence.
20Multicellular organisms arrived later, maybe two billion years ago.
21But it was only after the Cryogenian period that warmer conditions returned.
22That helped drive a quick expansion of different life forms about 540 million years ago.
23Scientists are trying to better understand the start of "Snowball Earth."
24They believe a greatly reduced amount of the sun's warmth reached the planet's surface as its radiation bounced off the white ice sheets.
25Seaweed and fossils of some other multicellular organisms were identified in the black shale.
26This seaweed was a photosynthetic organism living on the seafloor in a shallow sea environment lit by sunlight.
27"The fossils were preserved as compressed sheets of organic carbon," said researcher Qin Ye, also of China University of Geosciences.
28Multicellular organisms including red algae, green algae and fungi appeared before the Cryogenian and survived "Snowball Earth."
29The Cryogenian freeze was much worse than the most recent Ice Age that humans survived.
30It ended about 10,000 years ago.
31I'm Caty Weaver.
1Life 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. 2Scientists say Earth would have looked like a shiny white snowball in space during the deep freeze. 3But life somehow survived during this time called "Snowball Earth." A recent study offers a deeper understanding as to why. 4Fossils 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. 5Nature Communications published the research this month. 6The 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. 7The 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. 8Huyue 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. 9"More extensive areas of habitable oceans better explain where and how complex organisms such as multicellular seaweed survived," Song said. 10The 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. 11Earth 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. 12Scientists 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. 13Seaweed 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. 14"The fossils were preserved as compressed sheets of organic carbon," said researcher Qin Ye, also of China University of Geosciences. 15Multicellular organisms including red algae, green algae and fungi appeared before the Cryogenian and survived "Snowball Earth." 16The Cryogenian freeze was much worse than the most recent Ice Age that humans survived. It ended about 10,000 years ago. 17I'm Caty Weaver. 18Reuters reported this story. Caty Weaver adapted it for VOA Learning English. 19___________________________________________________________________ 20Words in This Story 21fossil -n. a sign or print or the remains of a plant or animal of a past age preserved in earth or rock 22ice sheet -n. huge areas of ice 23habitable -adj. an area or place that can support life 24compress -adj. pressed together: reduced in size or volume (as by pressure) 25photosynthetic -adj. of or related to the process by which plants and some bacteria and protists that contain chlorophyll make carbohydrates from water and from carbon dioxide in the air in the presence of light 26___________________________________________________________________ 27We want to hear from you. 28Here is how our comment system works: 29Each time you return to comment on the Learning English site, you can use your account and see your comments and replies to them. Our comment policy is here.