Posted on 07/21/2006 8:08:04 AM PDT by PatrickHenry
Ten years ago, an international team of scientists reported evidence, in a controversial cover story in the journal Nature, that life on Earth began more than 3.8 billion years ago—400 million years earlier than previously thought. A UCLA professor who was not part of that team and two of the original authors will report in late July that the evidence is stronger than ever.
Craig E. Manning, lead author of the new study and a professor of geology and geochemistry in the UCLA Department of Earth and Space Sciences, painstakingly mapped an area on Akilia
Island in West Greenland where ancient rocks were discovered that may preserve carbon-isotope evidence for life at the time of their formation. Manning and his co-authors—T. Mark Harrison, a UCLA professor of geochemistry, director of UCLA's Institute of Geophysics and Planetary Physics, and University Professor at the Australian National University; and Stephen J. Mojzsis, assistant professor of geological sciences at the University of Colorado, Boulder—conducted new geologic and geochemical analysis on these rocks. Their findings will be reported in the new issue of the American Journal of Science. Harrison and Mojzsis were co-authors on the Nov. 7, 1996, study in Nature.
"This paper shows, with far greater confidence than we ever had before, that these rocks are older than 3.8 billion years," said Manning, who has conducted extensive research in Greenland. "We have shown that the rocks are appropriate for hosting life.
"Everything from the basic geology to the analysis in the original report (in Nature) has been challenged," said Manning, who has expertise in areas that have become central to the debate, including the chemistry of water and the interaction of water and rock. "The chemical evidence for life has been challenged, as have been the minerals to determine whether life was present, whether the rocks have the origin that was originally attributed to them, and whether the rocks were as old as originally envisioned. We didn't go to Greenland in response to the criticism. We went to learn the age of the rocks and to make a better geologic map of the area than any that existed."
At the time of the 1996 Nature paper, there was no reliable map showing the geology of the area, Manning said. So he created one.
"I wandered around that outcrop for two-and-a-half weeks—it's not a big area—with a clipboard, maps, a compass and grid paper. We mapped it like an archeologist would map it," Manning said. "It became clear that these rocks that hosted life line up into two beautiful, coherent layers. They are not randomly distributed, as you might expect if the alternative interpretation is right. I'm very confident about that. I went to Greenland with some skepticism, but I became more and more confident as time went on that the original interpretation was right."
"It could have gone any way," Harrison said. "We could have placed the claim on much firmer footing, or we could have proved ourselves wrong. We found a much more compelling cross-cutting relationship in the rocks than we originally thought."
The new research is a comprehensive response to the critics, Harrison said.
"We've been holding our fire rather than fire away at each criticism in a piecemeal way," he said. "We've gone back to Greenland and done the study from the ground up, with much more data than existed at the time of the original paper. I'm much more confident today than I was in 1996 about the likelihood that this is evidence of early life. This is not 'smoking gun' evidence—we are not seeing fossils—but in every case, the model has come through with flying colors."
Manning agrees, saying he is confident the rocks contain evidence of ancient life, but "it's not a slam dunk."
Why is there doubt? After more than 3.8 billion years, the rocks are severely damaged.
"They have been folded, distorted, heated and compressed so much that their minerals are very different from what they were originally," Harrison said.
Why Akilia Island in Greenland?
"Akilia Island was not the best place to search for evidence of early life; it's simply the place where it turned up," Harrison said.
"There's nothing special about Akilia Island," Manning said. "If life was there, it should have been abundant on Earth 3.83 billion years ago. The only place where that's been tested so far, also in Greenland, has come up positive."
One of the key methods for dating the rocks is by carefully analyzing cross-cutting intrusions made by igneous rocks, Manning said, adding, "Whatever is cross-cut must be older than that which is doing the cross-cutting. We went there to find these cross-cutting relationships, which we did."
The research on the Akilia rocks is federally funded by the National Science Foundation (http://www.nsf.gov/) and the NASA Astrobiology Institute (http://nai.arc.nasa.gov/), a partnership between NASA, 12 major U.S. teams and six international consortia.
Scientists look for evidence of life in ancient rocks like those from Akilia Island by searching for chemical suggestions and isotopic evidence. The very strong isotopic evidence for ancient life found in the 1996 study included a high ratio of one form of carbon—an isotope—to another, which provides a "signature of life," Mojzsis said.
The carbon aggregates in the rocks have a ratio of about 100-to-one of 12C (the most common isotope form of carbon, containing six protons and six neutrons) to 13C (a rarer isotopic form of carbon, containing six protons and seven neutrons). The light carbon, 12C, is more than 3 percent more abundant than scientists would expect to find if life were not present, and 3 percent is very significant, Harrison said.
Carbon inclusions in the rocks were analyzed with UCLA's high-resolution ion microprobe—an instrument that enables scientists to learn the exact composition of samples. The microprobe shoots a beam of ions, or charged atoms, at a sample, releasing from the sample its own ions, which are then analyzed in a mass spectrometer. Scientists can aim the beam of ions at specific microscopic areas of a sample and analyze them.
While critics noted there are ways to make light carbon in the absence of life, Harrison considers those possibilities to be "extremely unlikely," especially in light of another discovery of rocks in Western Greenland, not far away, of the same age, and a similar ratio of 12C to 13C.
The scientists see light carbon inclusions in a phosphate mineral called apatite, which is also the material of which bones and teeth are made.
The form of life the researchers believe they have discovered was probably a simple microorganism, although its actual shape or nature cannot be ascertained, Mojzsis said, because heat and pressure over time have destroyed any original physical structure of the organisms.
Harrison said of UCLA's ion microprobe and the research: "The individual samples are very small, and no other instrument would have been sensitive enough to reveal precisely the isotopic composition and location of the carbon inclusions in the rock."
It is unknown when life first appeared on Earth, which is approximately 4.5 billion years old.
The residue of ancient life that the scientists believe they have found existed prior to the end of the "late heavy bombardment" of the Moon by large objects, a period which ended approximately 3.8 billion years ago, Harrison noted.
"Life is tenacious, and it completely permeates the surface layer of the planet," Mojzsis said. "We find life beneath the deepest ocean, on the highest mountain, in the driest desert and the coldest glacier, and deep down in the crustal rocks and sediments."
An unanswered question is how life originally could have arisen from lifeless molecules and evolved into the already sophisticated isotope fractioning life forms recorded in the Akilia rocks.
The American Journal of Science is the oldest scientific journal in the United States that has been published continuously, dating back to the 19th century. While the journal is being published in late July, it will carry a date of May 2006.
California's largest university, UCLA enrolls approximately 38,000 students per year and offers degrees from the UCLA College of Letters and Science and 11 professional schools in dozens of varied disciplines. UCLA consistently ranks among the top five universities and colleges nationally in total research-and-development spending, receiving more than $820 million a year in competitively awarded federal and state grants and contracts. For every $1 state taxpayers invest in UCLA, the university generates almost $9 in economic activity, resulting in an annual $6 billion economic impact on the Greater Los Angeles region. The university's health care network treats 450,000 patients per year. UCLA employs more than 27,000 faculty and staff, has more than 350,000 living alumni and has been home to five Nobel Prize recipients.
for starters ... human life didn't start off with Adam and Eve. .... No way in hell noah's ark could carry two of every species on earth ... i'd love to see 50 billion species times 2 fit on a boat.... for the sake of arguement ... check out Penn and Tellers show: "B*llsh*t" .. the one about religion specifically.. then come back and challenge me.
No I didn't I said they have found edvience in digs of human life that far back. It surprised me as well - they have also found batteries in digs in egypt dating back over a thousand years.
I was listening to the radio and they were interviewing an author of a book and he has put together "stuff" found in digs around the world that don't fit into any time line or one off items that don't fit the accepted norms of science.
What constitutes 'evidence of human life' in those digs?
Without some verification of that claim I will have to conclude it is hogwash. Do you have the name of the author? Or the name of his book?
You are correct. I usually add the *in the USA* part; I was lazy today. :)
What stupidity. But all billion year old theory is. Carbon dating rocks is just another desperate step in the failed evolution theory. It's like finding an arrow head, claiming it's a million years old, but made from a stone that's less than a thousand. Or, finding an arrowhead I carved 20 years ago, and threw away, which was then re- found, taken to a geoligist, who then claims it's 5,000 years old, carved by an ancient indian tribe who used to live in the area. An interesting aside to this story, is that it claims greenland was much greener than it is now, which we do know is true because of the fox, rabbits wolfs elephants, rino's that are found in the artic circle on several continents, suddenly buried and preserved in ice of recent age, proving sudden global catastrophic event. Fountains of the Great Deep Lot's of info about rocks here.
"If you believe in evolution, you think you have come to know the accidental meaninglessness of your existence."
I accept evolution and in no way do I find my life to be meaningless.
In this case they're talking about very primitive single cell bacteria.
"But all billion year old theory is. Carbon dating rocks is just another desperate step in the failed evolution theory."
Rocks aren't carbon dated.
"What stupidity."
True.
A Christian evolutionist? HAHAHAHA!
That's like dry water.
I would agree. An even stronger case could be made if life or its remains were found on other bodies in the Solar System.
"A Christian evolutionist? HAHAHAHA!"
Most people who accept evolution in the USA are Christians.
Now, a *creation scientist*: THAT'S like dry water.
I don't follow your logic. Please elaborate.
BTW, your claim that rocks are carbon dated is still wrong.
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