Recently, a new discovery of microfossils present in a piece of rock indicated that life existed almost 3.5 billion years ago. Scientists were surprised by the unexpected age of the ancient fossil. From the discovery, they found out that life existed on earth in the form of bacteria and microbes as far as 3.5 billion years. But at that time, there was no oxygen in Earth’s atmosphere, and the surface of the earth was extremely harsh. Repeated volcanic eruptions and constant bombardment by asteroids and other deadly space rocks, made earth almost inhabitable at that time. So, finding an ancient fossil that hints about one of the oldest earliest forms of life on Earth has pushed scientists to think about the possibility of alien life in many of the other planets in the Universe.
As the scientists got to know that tiny microbes and bacteria which are not visible to naked eye, existed 3.5 billion years ago in an oxygen-less environment, they are now hypothesizing that alien life could have been possible on other planets having the same type of conditions. As per the scientists, among those tiny microbes and bacteria that lived in the inhospitable conditions of Earth, some were photosynthesizer. Also, some produced methane and a few of them consumed methane. These primitive photosynthesizers are believed to be dwelling in those areas where there is plenty of light and negligible oxygen.
There are many planets outside world that have such type of conditions on their surface. You can take the example of Mars as well as its moon Titan, which has liquid methane on its surface. Hence, all these things indicated that just like our Earth had primitive photosynthesizers, other planets might also have photosynthesizers like microbes or bacteria which we call as alien life. And, scientists have now started believing that alien life may be more widespread in the Universe than previously thought.
Lead researcher William Schopf, a professor of palaebiology at UCLA, said that it was not difficult for primitive life to form and to evolve into more advanced microorganisms. He and his colleague John W. Valley, professor of geoscience at the University of Wisconsin-Madison used a new technique called secondary ion mass spectrometer (SIMS) to estimate the age of the microfossil more precisely. This SIMS technology uses carbon isotope ratios of microfossil to estimate its age. Although the latest discovery of 3.5 billion-year-old fossil indicates about earliest forms of life in the harsh in inhospitable condition, we cannot completely sideline the fact that at that time many other worlds might have also been home to alien life.