Life hits 4.1 billion years
3 Dec 2015 by qwwqdccwwm.d qwwqdccwwm.d
New evidence suggests that life on Earth began 300 million years earlier than previously thought.
New evidence suggests that life on Earth began 300 million years earlier than previously thought.
A research team at the University of California Los Angeles (UCLA) analysed more than 10,000 zircons – minerals that can capture and preserve their immediate environment – from Western Australia and found a 4.1 billion year old carbon mineral within the sample and suggested life may have begun shortly after the formation of Earth.
“Twenty years ago, this would have been heretical; finding evidence of life 3.8 billion years ago was shocking. Life on Earth may have started almost instantaneously. With the right ingredients, life seems to form very quickly,” said Professor Mark Harrison from UCLA.
The geochemists identified 656 zircons containing dark specks and analysed 79 of them with Raman spectroscopy. This allowed them to observe their molecular and chemical structure and study ancient organic compounds in 3D. In one zircon sample, they found the carbon mineral graphite; thought to be the chemical basis of all known life.
Professor Harrison said: “This is the first time that the graphite ever got exposed in the last 4.1 billion years. 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 results, published in the journal Proceedings of the National Academy of Sciences, showed that the carbon contained in the crystal has a characteristic signature – a specific ratio of 13C/12C – that indicates the presence of photosynthetic life. The scientists suggest that this offers evidence 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 research assistant Patrick Boehnke.
Paper: http://www.pnas.org/content/early/2015/10/14/1517557112.full.pdf
