Newly discovered evidence of the oldest fossils of land creatures ever found could tell scientists where to begin the search for life on Mars.
According to NPR, scientists have found biological signatures of land-based life in rocks dating to an earlier time than previously attributed to the existence of land creatures. The rocks predate the previous earliest date for land life by about 600 million years.
The rocks with the evidence for ancient microbial life also show signs that a hot spring existed in the same location. The rock samples contain geyserite deposits, which are only found in hot spring environments. This find lends some credence to the theory that life on Earth may have started in land-bound hot springs instead of near hydrothermal vents on the sea floor.
The evidence for ancient life in the hot springs includes stromatolites — layered structures created by masses of microbes, other “textures” indicating communities of microbes, and bubbles which may have been formed by a sticky material created by microbial activity.
The find is “a geological perspective saying actually, really early on we’re already seeing life on land,” Tara Djokic of the University of New South Wales said. “So it just lends weight potentially to an argument suggesting that the origin of life on land might be something to consider.”
The find also suggests that scientists looking for evidence of life on Mars may want to consider an area that once hosted hot springs. One of the landing sites under consideration by NASA for its 2020 Mars Exploration Mission is a “hot spring-like setting.”
“If you’re going to look for life on Mars, we know it was preserved on hot springs here on the ancient earth,” Djokic said. “So there’s a good chance if it ever developed on Mars, then it would probably be preserved in hot springs there, too.”
The study was published in the journal Nature Communications.