Straughn
09-06-2006, 10:06
This certainly garners a bit of worthwhile attention:
http://www.chicagotribune.com/news/nationworld/chi-0606080140jun08,1,933559.story?coll=chi-newsnationworld-hed
Rocks may hold key to oldest life
A team of scientists argues that a 6-mile stretch in Australia contains not geologic features but the earliest fossil evidence of life on Earth
By Peter Gorner
Tribune science reporter
Published June 8, 2006
As microbes go, they're renegades, perfectly at home in the world's hottest, coldest, saltiest or most sulfuric waters. They hang out near hydrothermal vents on the ocean floor or in the hot springs at Yellowstone, and happily colonize our digestive tracts and those of cows, termites and marine organisms.
This microscopic branch of life--called archaea--likely has been thriving for more than 3.4 billion years, according to new research from a team of Australian scientists. Writing in the journal Nature, they argue that miles of oddly shaped mounds of layered sedimentary rock found in Western Australia are not geologic features but the very earliest fossil evidence of life on Earth.
The rocks, they say, are remnants of thriving microbial communities that dominated the world in the days when the young planet roiled with boiling oceans and the atmosphere was rich in ammonia and methane and probably sizzling hot. Those conditions, while toxic to plants and animals, can nurture archaeans.
If the scientists are right, life arose on Earth within a billion years of its formation--very quickly in geologic time. The findings are relevant to the search for signs of extraterrestrial life on Mars and other planets or moons where conditions could support similar organisms.
"I think that these rocks are telling us that life probably arose ... rather quickly, which means that life only needs a short period of `habitable' conditions on a planet in order to gain a foothold," said the study's lead author, Abigail Allwood of the Australian Centre for Astrobiology at Macquarie University in Sydney.
"The study gives me much more optimism that life could have gained a foothold early in the history of Mars, even if it were only briefly habitable."
The research involves rock formations called stromatolites in Australia's Pilbara region. Approximately 3,430 million years old, the rocks have been a source of controversy since they were first described almost three decades ago.
Some scientists think they were formed not by the activity of primitive microbes but by hydrothermal vents--a chemical rather than biological process.
"The origins have been highly contentious," Allwood said. "There's a whole spectrum of opinion about whether or not there's evidence of life in rocks of this age. A leading expert says there's no consensus among scientists for life's existence prior to 1.9 billion years ago. That's an extreme view that highlights the ongoing debate about the issue."
A similar argument arose in 1996 when a team of NASA and Stanford University researchers asserted that a meteorite recovered from Antarctica contained evidence of possible past microbial life on Mars. Many researchers remain unconvinced that the meteorite has any potential to show that life once existed there.
Examining thousands of mounds in a 6-mile stretch of stromatolite-rich rock, Allwood and her colleagues identified seven differently shaped types. Some look like upside-down ice cream cones, others like egg cartons, fossilized sand dunes or choppy waves.
Their variety, the team concluded, makes them too complex to be chemical in nature. They believe each type represents its own environmental niche. Viewed as a whole, the stromatolites resemble a reef formation, suggesting the presence of Earth's first complex ecosystem.
"Previously, the structures were treated generically as one type, but we found and documented seven clearly different types," Allwood said.
"It's not the complexity of the forms alone; it's the association of the attributes--such as the increasing complexity as they go into shallow water. Plus, you find different, unusual and complex shapes occurring right next to one another. ... It's easily explained by biology, but you'd be hard pressed to explain it by anything else."
The microbes are free-swimming, but they can form a community at the ocean surface or on top of sediments on the sea floor, Allwood said. There they can leave a mark by influencing the way sediment is deposited.
"Stromatolites occur when microbes cause structures to accrete a variety of different shapes," she said. "Microbes can trap and bind different sediment grains that fall. Or they can cause mineral cements to precipitate around them. The microbes are alive when it happens."
Scientists unconnected to the work were quick to announce their enthusiasm for the Australian research.
"This is a real big issue they're addressing, and I think they're doing it the right way," said Peter Wagner, an associate curator of fossil invertebrates at the Field Museum in Chicago.
"If we go to places like Mars, we should be able to apply the same principles to the rocks there. There's lots of sandstones and shales; you can see features you see on Earth caused by standing bodies of water and running water.
"The thing to keep in mind is that Mars has only been loosely explored. The land area is actually greater than Earth. We've sent a handful of probes and the rovers, but it's such a drop in the bucket.
"Who knows what we'll find if we really start looking?"
--
also:
http://www.guardian.co.uk/australia/story/0,,1792645,00.html
Of course, i know a few of y'all will probably argue about this.
http://www.chicagotribune.com/news/nationworld/chi-0606080140jun08,1,933559.story?coll=chi-newsnationworld-hed
Rocks may hold key to oldest life
A team of scientists argues that a 6-mile stretch in Australia contains not geologic features but the earliest fossil evidence of life on Earth
By Peter Gorner
Tribune science reporter
Published June 8, 2006
As microbes go, they're renegades, perfectly at home in the world's hottest, coldest, saltiest or most sulfuric waters. They hang out near hydrothermal vents on the ocean floor or in the hot springs at Yellowstone, and happily colonize our digestive tracts and those of cows, termites and marine organisms.
This microscopic branch of life--called archaea--likely has been thriving for more than 3.4 billion years, according to new research from a team of Australian scientists. Writing in the journal Nature, they argue that miles of oddly shaped mounds of layered sedimentary rock found in Western Australia are not geologic features but the very earliest fossil evidence of life on Earth.
The rocks, they say, are remnants of thriving microbial communities that dominated the world in the days when the young planet roiled with boiling oceans and the atmosphere was rich in ammonia and methane and probably sizzling hot. Those conditions, while toxic to plants and animals, can nurture archaeans.
If the scientists are right, life arose on Earth within a billion years of its formation--very quickly in geologic time. The findings are relevant to the search for signs of extraterrestrial life on Mars and other planets or moons where conditions could support similar organisms.
"I think that these rocks are telling us that life probably arose ... rather quickly, which means that life only needs a short period of `habitable' conditions on a planet in order to gain a foothold," said the study's lead author, Abigail Allwood of the Australian Centre for Astrobiology at Macquarie University in Sydney.
"The study gives me much more optimism that life could have gained a foothold early in the history of Mars, even if it were only briefly habitable."
The research involves rock formations called stromatolites in Australia's Pilbara region. Approximately 3,430 million years old, the rocks have been a source of controversy since they were first described almost three decades ago.
Some scientists think they were formed not by the activity of primitive microbes but by hydrothermal vents--a chemical rather than biological process.
"The origins have been highly contentious," Allwood said. "There's a whole spectrum of opinion about whether or not there's evidence of life in rocks of this age. A leading expert says there's no consensus among scientists for life's existence prior to 1.9 billion years ago. That's an extreme view that highlights the ongoing debate about the issue."
A similar argument arose in 1996 when a team of NASA and Stanford University researchers asserted that a meteorite recovered from Antarctica contained evidence of possible past microbial life on Mars. Many researchers remain unconvinced that the meteorite has any potential to show that life once existed there.
Examining thousands of mounds in a 6-mile stretch of stromatolite-rich rock, Allwood and her colleagues identified seven differently shaped types. Some look like upside-down ice cream cones, others like egg cartons, fossilized sand dunes or choppy waves.
Their variety, the team concluded, makes them too complex to be chemical in nature. They believe each type represents its own environmental niche. Viewed as a whole, the stromatolites resemble a reef formation, suggesting the presence of Earth's first complex ecosystem.
"Previously, the structures were treated generically as one type, but we found and documented seven clearly different types," Allwood said.
"It's not the complexity of the forms alone; it's the association of the attributes--such as the increasing complexity as they go into shallow water. Plus, you find different, unusual and complex shapes occurring right next to one another. ... It's easily explained by biology, but you'd be hard pressed to explain it by anything else."
The microbes are free-swimming, but they can form a community at the ocean surface or on top of sediments on the sea floor, Allwood said. There they can leave a mark by influencing the way sediment is deposited.
"Stromatolites occur when microbes cause structures to accrete a variety of different shapes," she said. "Microbes can trap and bind different sediment grains that fall. Or they can cause mineral cements to precipitate around them. The microbes are alive when it happens."
Scientists unconnected to the work were quick to announce their enthusiasm for the Australian research.
"This is a real big issue they're addressing, and I think they're doing it the right way," said Peter Wagner, an associate curator of fossil invertebrates at the Field Museum in Chicago.
"If we go to places like Mars, we should be able to apply the same principles to the rocks there. There's lots of sandstones and shales; you can see features you see on Earth caused by standing bodies of water and running water.
"The thing to keep in mind is that Mars has only been loosely explored. The land area is actually greater than Earth. We've sent a handful of probes and the rovers, but it's such a drop in the bucket.
"Who knows what we'll find if we really start looking?"
--
also:
http://www.guardian.co.uk/australia/story/0,,1792645,00.html
Of course, i know a few of y'all will probably argue about this.