Scientists discover world's oldest fossil

Scientists announced Wednesday that they have discovered a fossil of microscopic organisms dating 3.7 billion years ago, making it the oldest evidence of life on Earth ever found. The fossil found in Greenland is 220 million years older than anything found previously. Scientists theorize the only known planet to harbor life formed 4.6 billion years ago.

If the discovery is confirmed, the recently uncovered fossil suggests life formed less than 1 billion years later, an extremely short period of time, cosmically speaking. Soon after its birth, Earth was barely more hospitable than other planets in the solar system. The finding, then, makes it easy to accept that life could have begun elsewhere, such as Mars, Earth's planetary neighbor. The fossil is called a stromatolite, a rocky structure created by bacteria. The specific type of bacteria to make the stromatolite is known as cyanobacteria, microbes that use photosynthesis to process energy from the sun and that are some of oldest species on the planet. The international team published the discovery Wednesday in the journal Nature, noting that the fossil was found in the "Isua supracrustal belt" (ISB) in southwest Greenland, which is home to some of the oldest rocks ever found.

"The ISB stromatolites grew in a shallow marine environment, as indicated by seawater-like rare-Earth element," researchers wrote in the study. In a commentary published alongside the discovery, Abigail Allwood, an astrobiologist working for NASA, explained why the discovery has extraterrestrial implications. "Earth's surface 3.7 billion years ago was a tumultuous place, bombarded by asteroids and still in its formative stages," Allwood wrote. "If life could find a foothold here, and leave such an imprint that vestiges exist even though only a minuscule sliver of metamorphic rock is all that remains from that time, then life is not a fussy, reluctant and unlikely thing. Give life half an opportunity and it'll run with it," she added.