Life arose on Earth melted
Findings of carbon of organic origin reveal that living organisms on the planet originated considerably earlier than was believed until now.
Researchers from Japan found traces of graphite of biogenic origin in sediments on the Labrador Peninsula (Canada). Such traces of no less than a 3.95 billion years. At this point, as it is believed, the planet had a permanent hard surface, because the surface was mostly molten permanent impacts of large asteroids. The existence of life at this point indicates its high resistance to adverse conditions.
The authors analyzed samples of ancient rock 3.95 billion years old and found in them traces of biogenic graphite. The content of isotopes of carbon-13 in it was reduced compared to purely abiotic scenario for the formation of graphite. Organisms-autotrophs prefer to pick up from the environment, mainly carbon-12 instead of the heavier carbon-13, whose involvement in the synthesis requires a large amount of energy. Based on this the researchers conclude that the isotopic composition typical of these rocks indicates the existence of autotrophic life for four billion years ago.
Separately noted that in the studied samples is markedly high content of lanthanum, europium and yttrium. These elements in sedimentary rocks occur more often than usual where they were deposited in the formations arising from the interaction of seawater and fluids from hydrothermal vents. It is near such sources are believed, and was supposed to be the earliest life on earth.
According to modern concepts, of 3.95 billion years ago the Earth was the Late heavy bombardment. During this period, the constant falling asteroids leave the main part of the surface of the planet molten. Only in areas covered with water, the situation was a little easier, although the temperature there was still extremely high by modern standards. Previously it was thought that to cool the planet 3.8 billion years ago life on it was not.
The earliest Dating of the origin of living organisms was indicated by 3.7 billion years ago. The new date moves significantly in the past appearance of the first body. In addition, it indicates that this event can happen even on a planet with extremely negative (at first glance) conditions.
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