Scientists analysed the oldest known fossil micro organisms that indicate life on Earth originated around 3.5 million years ago, and based on this, they say that alien life in the universe may be much more common than thought.
Scientists from the University of California, Los Angeles, and the University of Wisconsin-Madison in US found that the two species which they studied performed a primitive form of photosynthesis, one produced methane gas, and the other two consumed methane and used it to build their cell walls.
The micro-organisms are 3.465 billion years old and are taken from Western Australia. This evidence of such life at an extremely early time on the Earth suggests the case of life existing elsewhere in the universe.
Professor J William Schopf, professor at Universtiy of California, Los Angeles and the lead author of the study, said, “By 3.465 billion years ago, life was already diverse on Earth; that’s clear - primitive photosynthesizers, methane producers, methane users. These are the first data that show the very diverse organisms at that time in Earth’s history, and our previous research has shown that there were sulphur users 3.4 billion years ago as well.”
“This tells us life had to have begun substantially earlier and it confirms that it was not difficult for primitive life to form and to evolve into more advanced microorganisms,” he added.
The study, published in the journal PNAS, is the most detailed conducted on micro-organisms preserved in such ancient fossils.
For the study, the scientists used cutting-edge technology called secondary ion-mass spectroscopy (SIMS), which reveals the ratio of carbon-12 to carbon-13 isotopes.
Schopf said the fossils were formed at a time when there was very little oxygen in the atmosphere.
The average lifetime of a fossil exposed on the surface of the Earth is about 200 million years.
While the study suggests the presence of primitive life forms throughout the universe, Schopf said the presence of more advanced life is less certain but certainly possible.