The find is also significant for the search for life on Mars and other planets.
Our "surface centric" view of life on Earth, Parkes said, may mean we're looking in the wrong places for life elsewhere.
"There are [nonbiological] sources that can produce methane [and related chemicals]," he said. "Therefore there might be a biosphere on other planets that may not require" the ability to harness sunlight on a planet's surface for energy.
Other scientists agree.
"The more places we look for life, the more places we find it," said Dennis Geist, a University of Idaho geologist who was not involved in the study. "This [new study] furthers the notion that the days of limiting our search for new life to surface conditions are long gone," he continued by email.
"The findings of this work push the limits in terms of both pressure and temperature."
In fact, Geist notes, the drilling for the core samples used in the study began on a seafloor 2.8 miles (4.5 kilometers) beneath the waves, where the water temperature is barely above freezing. The drilling ended at a point beneath the ocean bed where the temperature is nearly equal to that of a boiling pot of water.
"The range of physical conditions is enormous."
(Related: "Alien Life Can Survive Trip to Earth, Space Test Shows" [November 12, 2007].)
The new study was published today in the journal Science.
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