http://www.space.com/scienceastronomy/lava_life_040422.html
Using a method never applied to rock from ancient Earth, researchers have found possible signs of biological activity dating back nearly 3.5 billion years, earlier than any other agreed-upon discovery of life on this planet. The primordial life appears to have eaten rocks to survive. Meanwhile, separate work is turning up intriguing similar structures in Mars rocks found on Earth, though no claims of life have yet been made with regard to this ongoing Martian investigation. If the terrestrial finding is confirmed, it means life was thriving not long after this world had been presumably sterilized several times over by asteroid and comet impacts that were common in the earliest era of the solar system, which is about 4.6 billion years old. The researchers found microscopic tubes in ancient, glassy lava that they say were created by microbes eating into the lava after it cooled on the ocean floor. Similar signatures of life, including genetic material, have been found in lava that formed more recently in Earth's history. Scientists generally agree that the tubes in the more modern lava were indeed creating by boring organisms. The 3.5-billion-year-old tubes contain carbon and traces of carbonates that could represent organic material left behind by the primitive organisms. The research was led by Harald Furnes atNorway's University of Bergen and is reported in the April 23 issue of the journal Science. Of life, evolution and sex Separately, scientists are engaged in an ongoing debate over purported microfossils in rock found in Australia, also said to be about 3.5 billion years old, and even older "graphite inclusions" in rocks from Greenland. Meanwhile, the oldest solid evidence for life dates back 3.2 billion years. Nobody knows how life began. Scientists aren't even sure if it started on Earth first or was transported here by Mars rocks or in the bellies of comets. They do know that Earth was initially inhospitable and probably dry as a bone when it formed about 4.5 billion years ago. Pockmarks on the Moon testify to an early history of asteroid and comet impacts that might have killed any living things on Earth or thwarted the development of life for the first few hundred million years. (Earth would have a similar frequency of scars but they were folded inward and eroded away.) Or, others argue, catastrophe may have been the mother of evolution, wiping out all but the hardiest life and forcing certain favorable mutations. For example, one study suggests a later, milder bout of cosmic poundings led primitive creatures down the path of mutation toward their first sexual encounters. The latest findings The newest discovery was made in lava that was once buried at the bottom of the sea but is now exposed in the so-called Barberton Greenstone belt in South Africa. "Our data come from entirely different rocks than those in which the search for early life has done previously," study leader Furnes told SPACE.com. "The biosignals we have applied are different from those previously used," Furnes said. "I think comparing our results with those on which the controversies presently are going on, would be like comparing apples and oranges." Little is known about the microbes and what they ate, Furnes explained. They apparently created some sort of microenvironment that dissolved the glassy lava rock, in order to drill into it. "We know very little about this, and from the biosignals we see in the Barberton lavas it is impossible to tell," Furnes said. "Attempts to culture microbes that settle and dissolve young glassy lavas are few. >From the few data that exist, however, it appears that the microbes gain energy from oxidizing iron." In an analysis of the work in Science, other researchers not involved in the study offered varying perspectives. Controversy continues �To me, it�s unequivocal that the textures they see were created by microorganisms," petrologist Martin Fisk of Oregon State University told the journal. "I think they�ve got the best evidence I�ve seen for life at that time.� Microbial geochemist Jennifer Roberts of the University of Kansas called the evidence compelling but said it's not a smoking gun. She said nonbiological processes can create similar tube-like structures. In a telephone interview, Fisk said he is "still open" to the interpretation that the tubes were created by something other than living things, but he added that no one has demonstrated what nonbiological process would actually be at work. Fisk has been aware of Furnes' work for some time, and separately he's been trying to find similar microscopic signatures of life in Mars rocks that have been found on Earth. So far, he said, he's not found anything that conclusively suggests life on Mars. But in a few grains of the mineral olivine, from Mars meteorites, he's noted shapes similar to those found in terrestrial rocks by Furnes and others. Fisk and his colleagues presented their preliminary findings last month at the Lunar and Planetary Science Conference, held in Houston. xponent Axis Of Origins Maru rob
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