A new analysis of the oldest known fossil microorganisms provides strong evidence to support an increasingly widespread understanding that life in the universe is common.
The microorganisms, from Western Australia, are 3.465 billion years old. Scientists from UCLA and the University of Wisconsin–Madison report today in the journal Proceedings of the National Academy of Sciences that two of the species they studied appear to have performed a primitive form of photosynthesis, another apparently produced methane gas, and two others appear to have consumed methane and used it to build their cell walls.
The evidence that a diverse group of organisms had already evolved extremely early in the Earth’s history — combined with scientists’ knowledge of the vast number of stars in the universe and the growing understanding that planets orbit so many of them — strengthens the case for life existing elsewhere in the universe because it would be extremely unlikely that life formed quickly on Earth but did not arise anywhere else.
“By 3.465 billion years ago, life was already diverse on Earth; that’s clear — primitive photosynthesizers, methane producers, methane users,” said J. William Schopf, a professor of paleobiology in the UCLA college, and the study’s lead author. “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 sulfur users 3.4 billion years ago as well.
Taken from the following: Universal Micro-organic Life