- 19 Jan 2016 01:44
#14643563
Life on earth is older by 300M years than previous research has indicated.
http://www.pnas.org/content/112/47/1451 ... 4da223fe66
http://www.sci-news.com/geology/science ... 03356.html
UCLA scientists have found evidence that life likely existed on Earth at least 4.1 billion years ago -- 300 million years earlier than previous research suggested. The discovery indicates that life may have begun shortly after the planet formed 4.54 billion years ago.
The new research suggests that life existed prior to the massive bombardment of the inner solar system that formed the moon's large craters 3.9 billion years ago. "If all life on Earth died during this bombardment, which some scientists have argued, then life must have restarted quickly," said Patrick Boehnke, a co-author of the research and a graduate student in Harrison's laboratory.
The researchers studied more than 10,000 zircons originally formed from molten rocks, or magmas, from Western Australia. Zircons are heavy, durable minerals related to the synthetic cubic zirconium used for imitation diamonds. They capture and preserve their immediate environment, meaning they can serve as time capsules. The carbon contained in the zircon has a characteristic signature -- a specific ratio of carbon-12 to carbon-13 -- that indicates the presence of photosynthetic life.
How confident are they that their zircon represents 4.1 billion-year-old graphite? "Very confident," Harrison said. "There is no better case of a primary inclusion in a mineral ever documented, and nobody has offered a plausible alternative explanation for graphite of non-biological origin into a zircon."
The graphite is older than the zircon containing it, the researchers said. They know the zircon is 4.1 billion years old, based on its ratio of uranium to lead; they don't know how much older the graphite is.
http://www.pnas.org/content/112/47/1451 ... 4da223fe66
http://www.sci-news.com/geology/science ... 03356.html
UCLA scientists have found evidence that life likely existed on Earth at least 4.1 billion years ago -- 300 million years earlier than previous research suggested. The discovery indicates that life may have begun shortly after the planet formed 4.54 billion years ago.
The new research suggests that life existed prior to the massive bombardment of the inner solar system that formed the moon's large craters 3.9 billion years ago. "If all life on Earth died during this bombardment, which some scientists have argued, then life must have restarted quickly," said Patrick Boehnke, a co-author of the research and a graduate student in Harrison's laboratory.
The researchers studied more than 10,000 zircons originally formed from molten rocks, or magmas, from Western Australia. Zircons are heavy, durable minerals related to the synthetic cubic zirconium used for imitation diamonds. They capture and preserve their immediate environment, meaning they can serve as time capsules. The carbon contained in the zircon has a characteristic signature -- a specific ratio of carbon-12 to carbon-13 -- that indicates the presence of photosynthetic life.
How confident are they that their zircon represents 4.1 billion-year-old graphite? "Very confident," Harrison said. "There is no better case of a primary inclusion in a mineral ever documented, and nobody has offered a plausible alternative explanation for graphite of non-biological origin into a zircon."
The graphite is older than the zircon containing it, the researchers said. They know the zircon is 4.1 billion years old, based on its ratio of uranium to lead; they don't know how much older the graphite is.
The old world is dying, and the new world struggles to be born: now is the time of monsters. -Antonio Gramsci