We have honest reason to believe life first appeared on Earth soon after the planet chill enough to support it . However , whether we can find traces of these early organisms has been highly controversial . Two papers from one team of scientist support the hypothesis that banding of graphite in ancient rock-and-roll amount from some of the earlier life-time phase . The work may expand our content to find life history on other planets .
Greenland hosts some of the universe ’s oldest hold up rocks . Among these , subatomic particle of graphitic atomic number 6 can be obtain , not unlike to the contents of a pencil ( google it , kids ) . The discovery of this atomic number 6 created plenteousness of enthusiasm , as it might be life ’s earliest clay . However , two other , much less exciting , theory have also been proposed – either the carbon had a non - biologic source , or it was from more recent dwell things that worked their way into the rocks long after they formed .
InEarth and Planetary Science Letters , a team including University College London’sDr Dominic Papineaumake the cause that the hop - for account is right . “ We now have multiple strand of grounds that these mineral associations are biologic in ring smoothing iron formations , ” Papineau said in astatement .
The black lead is trapped in banded iron rocks , some of which are more than 3.8 billion eld old . In 10 cases it has been found relate with apatite , a component of teeth and pearl that can also have non - biologic origins . They ’ve been transform under heat and force many geologists expected would ruin any distinctively biological chemicals trapped within them .
However , the paper reports the graphite is depleted in carbon-13 isotope , like material lay down by more recent life forms . The dispersion through the rocks is also uniform with the remains of organisms being posit by spicy fluid , such as from volcanically heated water .
In a 2d paper , published in theJournal of the Geological Society , Papineau demonstrates life ’s traces can make it like metamorphosis . He used band smoothing iron formation from Michigan , less than half the age of their Greenland opposite number .
The shapes of animals within the Michigan rocks reveal they once held life , but they have experienced temperature of at least 550ºC ( 1,022ºF ) . Yet graphitic carbon in these rocks has formed expatiate fretwork containing chemical and isotopic signatures of sprightliness . If these could survive such temperatures and pressures , there is no reason to think they would n’t make it through another 2 billion days .
If Mars once hosted life , the traces it left behind would probably resemble these , leading Papineau toclaim : " This has Brobdingnagian conditional relation for how we determine the origin of carbon in sample of special - terrestrial rocks returned from elsewhere in the Solar System . “[H / thyroxin : Geological Society of London Blog ]
