According toa studypublished in the journalProceedings of the National Academy of Sciences(PNAS ) , after studying carbon sample found in graphite embedded in zircon crystals in Western Australia , researchers believe that life sentence on our satellite may have started hundreds of millions of long time earlier than previous estimation .
Elizabeth A. Bell and her carbon monoxide gas - authorsexplainthat " grounds of life on Earth is manifestly preserved in the rock disk , " but the record of microfossils ( so small-scale they ask a microscope to see ) only run back so far , to 3.5 billion years ago . Meanwhile , the chemofossil record ( chemicals from the decomposition of a once - hold out organism ) dates back to about 3.8 billion years ago , and the rock-and-roll phonograph recording to some 4 billion old age ago . However , last twelvemonth , zircon crystals werediscovered in the Jack Hillsof Western Australia that pre - see the stone platter by .4 billion years , making them the oldest know minerals on the satellite .
Bell and her team study more than 10,000 Jack Hills zircon crystals and discovered the graphite and carbon samples in a " tornado - free " region of the mineral . " We used the caesium ion shaft to drill through the [ zircon ] aerofoil and into the graphite , such that the graphite was never reveal to contaminant prior to analysis,“she toldScientific American . The research worker think that the plumbago was " incorporated during crystallisation of this igneous zircon . " That intend that if the atomic number 6 were produced by live organisms , then a " sublunar biosphere " may have formed around 4.1 billion years ago — that ’s around 300 million eld in the first place than scientists antecedently thought .
Bellalso toldScientific Americanthat while the isotope proportion of the carbon found ( which is used as an " indicator of life " in rocks ) could be a resultant of processes that do n’t involve living organisms , the conditions in which the graphite was discovered would make those alternative processes " incredibly complicated , perhaps unfeasibly so . "
The next step in confirming that the carbon was produce by living organisms would be to find and canvass more samples in the Jack Hills zircon crystals .
