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jpak Donating Member (1000+ posts) Send PM | Profile | Ignore Wed Jun-07-06 03:13 PM
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Fossils Point to Oldest Life on Earth
www.lasvegassun.com/sunbin/stories/tech/2006/jun/07/060705469.html

The best evidence yet for the oldest life on Earth is found in odd-shaped, rock-like mounds in Australia that are actually fossils created by microbes 3.4 billion years ago, researchers report.

"It's an ancestor of life. If you think that all life arose on this one planet, perhaps this is where it started," said Abigail Allwood, a researcher at the Australian Centre for Astrobiology and lead author of the new study. It appears Thursday in the journal Nature.

The strange geologic structures - which range from smaller than a fingernail to taller than a man - are exactly the type of early life astrobiologists are looking for on Mars and elsewhere.

They are known as stromatolites. They're produced layer by layer when dirt sediments mix with carbon dioxide expelled from bacteria, water, and minerals - all trapped in the microbes' sticky mucilage.

<more>
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villager Donating Member (1000+ posts) Send PM | Profile | Ignore Wed Jun-07-06 03:17 PM
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1. um, don't you mean "6,000 years old?"
:evilgrin:
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Wickerman Donating Member (1000+ posts) Send PM | Profile | Ignore Wed Jun-07-06 03:20 PM
Response to Reply #1
2. Adam was an amoeba?
:shrug:

:rofl:
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villager Donating Member (1000+ posts) Send PM | Profile | Ignore Wed Jun-07-06 03:32 PM
Response to Reply #2
3. well, not by the 6th day!
;-)
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texastoast Donating Member (1000+ posts) Send PM | Profile | Ignore Wed Jun-07-06 03:49 PM
Response to Original message
4. Are you an instrument of Satan?
EVERYONE knows the earth is only 6,000 years old.

:rofl:
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Posteritatis Donating Member (1000+ posts) Send PM | Profile | Ignore Sat Jun-10-06 07:18 PM
Response to Reply #4
12. Wow, never heard *that* one before... (n/t)
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eppur_se_muova Donating Member (1000+ posts) Send PM | Profile | Ignore Wed Jun-07-06 03:59 PM
Response to Original message
5. Book plug! "Cradle of Life" by J. William Schopf
from Amazon.com:

What if U.S. history began in 1963, and everything that happened before that year was shrouded in mystery? There would be plenty of events to study, but we wouldn't have a complete picture of the country's past. This is the analogy that paleomicrobiologist J. William Schopf uses to describe the long-missing 85 percent of earth's early fossil record (the puzzle of the missing fossils was known as Darwin's Dilemma). Not until the 1960s did paleobiologists using pickaxes and microscopes find evidence that life began much earlier than previously theorized and that microorganisms were the planet's only inhabitants for most of its existence. And Schopf himself discovered the oldest Precambrian fossils known to science in 1993. Why did it take so long to find these critters?

Though the puzzle of the "missing" early fossil record lived on for more than a hundred years, its solution is now so obvious as to be mundane. The Precambrian world did indeed swarm with living creatures, but until near the close of this vast eon these were microbes and microalgal cells so tiny and fragile that they would never have been unearthed by conventional fossil hunting.


Cradle of Life is a great primer for those interested in the fossil record and its relation to evolutionary theory. Profusely illustrated, this chronicle of amazing discoveries and bizarre questions covers wide ground, including the basics of cell biology and microevolution as well as the careers of the big-name scientists who have set the fossil record straight. And the search continues for the origins of life on earth, as well as the hints of it elsewhere. In a terrifically enlightening epilogue, Schopf shows how even the best scientists have been fooled by geological artifacts that resemble true fossils (as happened with the infamous Martian meteorite "bacteria") and by their own desires to confirm their theories and beliefs about the origins of life. --Therese Littleton --This text refers to the Hardcover edition.


I've only read about half this book, but it's been worth it so far. It explains quite clearly just why these microfossils are not found in most sedimentary rocks, even when they are of the right age, but only form under certain conditions--conditions which can be inferred from the location and type of rock, thus allowing paleontologists to identify those deposits most likely to contain archaic microfossils. The book includes numberous photomicrographs of fossil remains billions of years old. The author describes the history of this field with attention to the people involved--sometimes geniuses, sometimes misguided--and his own involvement, starting with his own undergraduate studies at Oberlin College (not far from here). If you've ever wondered how anyone could find and identify anything as obscure as a 2 billion year old microbe embedded in hard, silaceous rocks like chert, this book is for you.
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Odin2005 Donating Member (1000+ posts) Send PM | Profile | Ignore Wed Jun-07-06 09:50 PM
Response to Reply #5
9. Thats a great book.
Another good book on Precambrian life is Life on a Young Planet by Andrew Knoll.
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htuttle Donating Member (1000+ posts) Send PM | Profile | Ignore Wed Jun-07-06 04:07 PM
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6. As long as we're talking about our long, long dead relatives...
Do you (plural) think that all the existing life on Earth evolved from a single, primitive microbe (or proto-lifeform), or do you think that life on Earth evolved from numerous generations of those primitive microbes (or proto-lifeforms)?

In other words, was the first thing on Earth that could be considered 'alive' a single, lucky creature who then divided, divided, etc... and lead to what we see today, or was the process of becoming 'alive' repeated over and over, leading to 'unrelated' (from a microbial geneological point of view) life forms?

This leads me to another question I often ponder: If conditions are right, can new 'life' still evolve on Earth from non-life? Obviously if it did, it would have to follow a different course than the first life forms on Earth, since conditions are far different now than they were then, but is it possible?

These are some of the things Hydrogen atoms think about, given 15 billion years of cosmic evolution, to paraphrase Carl Sagan.

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Dead_Parrot Donating Member (1000+ posts) Send PM | Profile | Ignore Wed Jun-07-06 08:59 PM
Response to Reply #6
7. I'm guessing it happened many times...
If the conditions are right for life in one place, they were probably right in others, and at different times: It may have happened thousands of times.

Whether different geneses (Genisae?) florished, died out or merged is something we'll probably never know. It might be that viruses are totally unrealted to the Eocyte tree, and the Archaea group is seperate again, but I guess we'll never know for sure.

I'm intriqued by the idea of new life forming in modern times. I think most of the biosphere is now too too toxic from oxygen for that, but then who knows what we'll find floating around a thermal vent in Lake Vostok...

You think too much, y'know. :D
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Odin2005 Donating Member (1000+ posts) Send PM | Profile | Ignore Wed Jun-07-06 09:45 PM
Response to Reply #6
8. There was probably several origins of life, but only ours survivied.
Our kind of life was the most superior, biochemically, driving all the other types of life that originated into extinction. Our form of life probably originated as organic fims on iron sulfide crystals. One of these conquering microbes was LUCA, the Last Universal Common Ancestor of all life around today, probably living around 4 billion years ago. LUCA probably got it's energy from by turing hydrogen and carbon monoxide into methane and acetic acid (vinegar) with enzymes with tiny crystals of iron sulfide. Most of Life's most basic metabolic enzymes have these little iron sulfide crystals.

LUCA's Lineage then split into two. One lineage developed the abillity to photosynthesize, and the Eubacteria were born. Ancient sediments in greenland show that photosynthesis myst of been around by 3.85 billion years ago. The other branch developed more complex genetic machinery but retained the methanogenic habit, I'll call this branch the Proto-Archaebacteria.

The Proto-Archaebacteria split into two lineages around 3 billion years ago. One developed unique cell membranes that let them colonize the harshest enviroments, these became the true Archaebacteria. The other branch developed a sybiotic relationship with aerobic Eubacteria that allowed them to live in the oxygen-rich enviroments near stromatolites, this symbiosis become organisms with nuclei, the Eucarya.
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benburch Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Jun-11-06 12:19 AM
Response to Reply #8
13. Or, if you belive Stephen Jay Gould...
...we might not have been superior, just lucky.
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eppur_se_muova Donating Member (1000+ posts) Send PM | Profile | Ignore Wed Jun-07-06 10:18 PM
Response to Reply #6
11. A lot of bacteria swap DNA even with other species.
And there may be a lot of DNA in the human genome that was originally introduced by viruses (last I heard, anyway).

It's also believed that many organelles found in modern cells--such as mitochondria, and chloroplasts in plants--were originally independent organisms, then symbionts, then completely subsumed genetically. If so, it's possible that (proto)organisms which originated at different times and/or places combined to produce moder eukaryotes, at least. That would raise the possibility there was no single UCA.
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Odin2005 Donating Member (1000+ posts) Send PM | Profile | Ignore Wed Jun-07-06 09:54 PM
Response to Original message
10. This is great news.
Ever since these Australian stromatolites were discovered there was a persistent minority claiming they weren't biological (according to them the oldest stomatolites that were definitely biological were 3.2 billion year old ones in South Africa). Now the doubters can STFU.
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