Living microbes, possibly millions of years old, have been discovered more than five kilometers beneath the Pacific Ocean’s surface, in an area believed to have been devoid of life.
In a study published Tuesday, Japanese and American scientists described what they found in sediment samples taken from a flat, wide area 3.7 kilometers to 5.7 kilometers below the ocean’s surface, known as an abyssal plain. Because of their depth and the limited organic material in the sediment found there, these areas were long believed unable to support life.
But the researchers, whose work was published in the science journal Nature Communications, did find communities of microbes in ancient sediment, the oldest dating back more than 101 million years. They described the microbes as starving, with little food or energy, found in the sediment where they were trapped. When the researchers fed them back in the lab, the microbes grew, reproduced and flourished.
How the microbe communities survived for so long in such harsh conditions is still a mystery. Scientist speculated that the microbes found ways to exist and reproduce with little or no energy, or perhaps they survived via some yet undiscovered energy source. Or, they said, it is possible the microbes just live a very, very long time.
A co-author of the study, University of Rhode Island professor Steven D’Hondt, told the online science publication Inverse that they may eventually discover all three possibilities are true.
The existence of the microbes raises the possibility that life exists elsewhere where it was not thought possible, perhaps even on planets in our solar system. D’Hondt said, “There’s probably not a limit to life anywhere.”