Astronomers and evolutionary biologists have been looking for signs of alien life for decades. The scientific community believes that aliens do exist on other planets. A study of oldest known fossils on Earth provides strong evidence that alien life might be more ‘widespread’ in the universe than thought. Findings of the study were described in the journal Proceedings of the National Academy of Sciences (PNAS).
Life existed on Earth 3.5 billion years ago
In a 3.5 billion years old piece of rock from western Australia, scientists at the University of California Los Angeles have found fossils of the oldest known life forms. That’s quite surprising considering the surface of our planet 3.5 billion years ago was extremely harsh. There was little oxygen, too many volcanic eruptions, and the Earth was constantly bombarded by asteroids and other pieces of space rocks.
Despite the inhospitable conditions on early Earth, these tiny organisms had a miniature ecosystem. Some of them were photosynthesizers, a few others produced methane, while some organisms consumed methane. Their existence has led scientists to believe that the same thing must have happened on other planets as well. Primitive photosynthesizers lived where there is plenty of light but little oxygen, similar to the surface of Mars. Saturn’s moon Titan is believed to have liquid methane.
The fossils have been known for more than two decades, but they were subject of a controversy in the past. Many in the scientific community argued that the fossils were just unusual shapes in the rock rather than an evidence of ancient life. Researchers led by William Schopf at the UCLA analyzed the carbon composition of the ancient rock to find out the ratios of different carbon isotopes.
“The differences in carbon isotope ratios correlate with their shapes,” said researchers. It means they were indeed fossils of ancient microbes rather than just unusual shapes in the rock. Scientists found evidence of 11 different types of fossils in the said piece of rock. Professor William Schopf said in a statement, “It was not difficult for primitive life to form and to evolve into more advanced microorganisms.”
There could be primitive alien life forms throughout the universe
The fact that a variety of microbes had evolved extremely early in our planet’s history strengthens the case that life exists elsewhere in the universe. The UCLA said it would be “extremely unlikely” that life forms evolved in such harsh conditions so early on Earth but did not emerge anywhere else in the universe. There are billions of stars in the universe, and most of them have habitable planets orbiting them.
Though the new study “strongly suggests” that there could be primitive alien life forms throughout the universe, William Schopf said the presence of an advanced alien life was “very possible but less certain.” He added that life in the universe should be widespread if the conditions are right. The ancient microbes found in the Australian rock might not survive today’s oxygen-rich atmosphere. But the discovery shows that life finds a way to emerge even in environments that we think are inhospitable.