Are we alone in the Universe? Or any other life forms exist out there? A new study, published on the Proceedings of the National Academy of Sciences of the United States of America (PNAS)Notes 1 suggests that the life emerged so early on Earth – it should be widespread. In other words, the Universe should be filled with life.
The story goes back to 1982. 35 years ago, UCLA Scholar and Pioneer in Study of the Evolution of Life, J. William Schopf collected 3.465-billion-year-old fossils from the Apex Chert in western Australia, and interpreted them as early life. When he described the fossils in the journal Science in 1993, critics had argued that they were not early lifeforms – they were just odd minerals that only looked like biological specimens.
However, the new study, led by J. William Schopf and published on December 18, 2017, shows that they were indeed earliest life forms ever known. The researchers used an instrument called secondary ion mass spectrometer (SIMS, also known as the ion microprobe) to analyze the findings. The spectrometer is one of only a few in the world. It measures the ratio of carbon-12 to carbon-13 isotopes, thus helped the scientists determine the microbes’ anatomies. According to the study, within 11 microbial fossils, two of the species appear to have performed a primitive and earliest form of photosynthesis. Another specimen
To analyze the microorganisms, the researchers used an instrument called a secondary ion mass spectrometer (SIMS) — one of only a few in the world. By measuring the ratio of carbon-12 to carbon-13 isotopes, SIMS helped the scientists determine the microbes’ anatomies, and revealed how they lived.
The new study shows that two of the species appear to have performed a primitive form of photosynthesis, another apparently produced methane, a natural substance that can be produced over time through biological routes, and two others appear to have consumed methane and used it to build their cell walls.
Schopf says: “By 3.465 billion years ago, life was already diverse on Earth; that’s clear. 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.”
So, it seems the life started very early here on Earth. And, today we know that the universe contains at least 2 trillion galaxies (some researchers, for example, David Kornreich, an assistant professor at Ithaca College in New York State, thinks the number is much higher. He estimates that the number should be at least 10 trillion). There are around 100 billion stars in each galaxy, around 5%-20% of all stars are Sun-like, at least 22% of Sun-like stars harbor Earth-size planets orbiting in their habitable zones according to a recent study. So, there should be at least sextillions of Earth-like planets in the universe. Combining that with the results of the study, Schopf says:
“If the conditions are right, it looks like life in the universe should be widespread”.
- Proceedings of the National Academy of Sciences of the United States of America (PNAS) is the official scientific journal of the National Academy of Sciences, published since 1915.
- Study: “SIMS analyses of the oldest known assemblage of microfossils document their taxon-correlated carbon isotope compositions” on Pnas.org
- Proceedings of the National Academy of Sciences of the United States of America on wikipedia
- “Fossils suggest a universe filled with life” on EarthSky.org
- “Oldest fossils ever found suggest life in the universe is common” on Astronomy.com