Primitive microbes found in rocks covered by the sea 1.4 billion years ago are providing support for the theory that life may have originated in a type of "underwater chimney", Chinese scientists said recently.
The "geological evidence" found on rocks near the Great Wall in northeast China challenges the prevailing theory that evolution depended exclusively on sunlight, said Li Jianghai, professor with the earth and space institute attached to the elite Peking University .
The fossilized microbes, only microns in size, appeared bulbiform or filiform under an electronic microscope. They had been "capable of surviving in extreme conditions devoid of sunlight and oxygen, but with extreme temperatures and pressure."
The microbes obtained energy and nutrients through the conversion of toxic gas usually sulfured hydrogen, emitted from “black smoke-emitting chimneys” and were fatal to common life, according to Li.
The international scientific circle has long studied the mystery of the origin of life: how primitive organisms survived the earliest harsh climates, a time when there was little oxygen in the earth's atmosphere and no ozone shield sheltering terrestrial life and shallow water organisms from the sun's lethal ultraviolet radiation.
The finding at the foot of the Great Wall has supported the theory that deep-sea floors are the source of the earliest life on earth.
Experts said the finding was significant to the understanding of life's origin and to the exploration of exotic life forms on other planets. "It revealed good prospects for the search for lower life forms in places other than on earth," Li said.
"We have a lot of work to do in the coming months, including a profound field survey and the examination of characteristics and types of the fossilized microbes," Li noted, adding that comparative research was also being considered to study the relationship between relevant records and microorganisms currently living in hydrothermal vent locations in the ocean.
Since microbe-type organisms were able to survive without sunlight and oxygen on ancient earth, it is also possible to find similar lower life forms or fossils thereof on other planets.
The research of Li's international counterparts have confirmed the possibility of finding similar organisms on Mars and Jupiter, both of which have an environment similar to that of the primitive earth, according to Li.
The researchers discovered a large number of live microorganisms and their fossils near hydrogen-spewing "chimneys" on the ocean floor, and laboratory testing proved they possessed the most primitive genome on earth.
(Xinhua News Agency April 1, 2003)
