CARDIFF, Wales, Feb. 23 (UPI) -- Welsh scientists said they have found living bacteria inside sediments about 16 million years old and located about a half-mile below the ocean's surface.
BBC News Online reported Wednesday that the scientists, at Cardiff University, suspect that life on Earth could have evolved for some time in the deep sediments.
"It might be that life was developing in the subsurface long before (it took hold on the surface because) it was protected from meteorite impacts," said co-researcher John Parkes. As soon as Earth's surface became more hospitable, he said, "bacteria were able to move up and colonize it."
Scientists now estimate that 60 percent to 70 percent of all bacteria live beneath the world's surface, although conventional wisdom once was the depths of the Earth were entirely inhospitable to life.
"There was a classic publication in the 1950s that said life stopped a few (feet) below the sediment surface," Parkes said. "And now we find organisms in excess of (2,500 feet) deep."
The subsurface bacteria appear to feed on hydrogen produced by chemical processes, and they even might have played a role in the formation of oil, gas and coal deposits.
"These bacteria are growing very slowly in the subsurface," Parkes told the BBC Web site. "They could effectively be immortal."