Ancient diamonds may show life on earth spans 4.5 billion years

Ancient diamonds in the rocks of Western Australia could be at the center of a 21st century scientific bonanza.
Australian, Swiss and German researchers say that the rocks have evidence that life began 4.2 billion years ago. This is a mere 300,000 years after the formation of Earth 4.5 billion years ago.

Experts generally concur that life existed on earth about 3.5 billion years ago. And a handful of scientists believe that life existed 3.8 to 3.9 billion years in the past.

So this discovery has the potential to radically change our understanding of how long life has been on the planet.
A team led by geochemist Alexander Nemchin, of the Curtin University of Technology in Perth, conducted an analysis of 22 diamonds that were discovered inside zircon crystals that are three billion-4.25 billion years old. The zircons were unearthed in Australia in the Jack Hills, east of Shark Bay.

The diamonds are just 70 microns wide, which is the thickness of a few human hairs. The diamonds likely were formed under the pressure by 100-150km of rock above them.

Writing overnight in the journal Nature, Dr Nemchin`s team said that the diamonds contained two types, or isotopes, of carbon, C12 and C13. There appears to be more C12 than C13. As this is the ratio produced by biological processes, such "light" carbon is recognized as a signature of life that has formed.

The team leading the study stated that geochemical processes may have produced the shown isotopic composition, but that more study is needed.