Pond scum may hold tiniest known life-form


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Message boards : Science (non-SETI) : Pond scum may hold tiniest known life-form

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Message 489114 - Posted: 24 Dec 2006, 6:29:23 UTC

By William J. Broad
NEW YORK TIMES NEWS SERVICE

December 23, 2006

The smallest form of independent life known to science may have just gotten smaller.

Four million of a newly discovered microbe – assuming the discovery, reported yesterday in the journal Science is confirmed – could fit into the period at the end of this sentence.

Scientists found the microbes living in a remarkably inhospitable environment, drainage water as caustic as battery acid from a mine in Northern California.

The microbes, members of an ancient family of organisms known as archaea, formed a pink scum on green pools of hot mine water laden with toxic metals, including arsenic.

“It was amazing,” said Jillian F. Banfield of the University of California Berkeley, a member of the discovery team. “These were totally new.” In their paper, the scientists call the microbes “smaller than any other known cellular life-form.”

Scientists said the discovery could bear on estimates of the pervasiveness of exotic microbial life, which some experts suspect forms a hidden biosphere extending down miles whose total mass may exceed that of all surface life.

It may also influence the search for microscopic life-forms elsewhere in the solar system, a discovery that would prove life in the universe is not unique to Earth but an inherent property of matter.

The tiny microbes came from an abandoned mine at Iron Mountain in Shasta County, which produced gold, silver, iron and copper, and closed in 1963.

Today, rain and surface water run over exposed minerals, producing sulfuric acid. The mine is one of the largest Superfund cleanup sites.

Starting in 2002, the scientists obtained drops of the acidic slime and searched for genetic signs of novel microbes.

“We were essentially looking for new stuff,” said Brett J. Baker in a UC Berkeley statement, “and we found it.”

The microbes are about 200 nanometers wide.

That also is the size of large viruses. But most scientists do not consider viruses to be independent living organisms because they cannot reproduce on their own. Viruses hijack another organism's biological machinery to replicate.

Bacteria average about five times the size of the Shasta microbes.

The scientists must do further tests to confirm that the organisms are the smallest ever found, and that they can reproduce.

If those analyses hold up, they said in their Science paper, “it may be necessary to reconsider existing paradigms for the minimum requirements for life.”
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Message 489119 - Posted: 24 Dec 2006, 6:48:47 UTC

This belongs in the Science forum.
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Message 489484 - Posted: 24 Dec 2006, 18:22:35 UTC

This is the Science forum.
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Message 489568 - Posted: 24 Dec 2006, 19:39:08 UTC - in response to Message 489484.

This is the Science forum.


That's where it is now.
Back on topic, please.
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Message 490894 - Posted: 26 Dec 2006, 13:31:16 UTC - in response to Message 489114.
Last modified: 26 Dec 2006, 13:32:17 UTC

That also is the size of large viruses. But most scientists do not consider viruses to be independent living organisms because they cannot reproduce on their own. Viruses hijack another organism's biological machinery to replicate.

This could be argued forever but hijacking and replicating sound very life-like to me. Viruses do things rocks can't do. Deliberately doing anything at all seems like a definition of life.

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Message 490927 - Posted: 26 Dec 2006, 15:12:40 UTC

Yes Jim, I would tend to agree. To say that a virus is not a life-form because it needs a living host in order to reproduce is like saying a human without access to oxygen is not a lifeform because it cannot survive.

If something has a life-cycle (it is formed, it matures, it seperates/reproduces) then it is life.
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Message 490950 - Posted: 26 Dec 2006, 16:20:03 UTC - in response to Message 490894.

That also is the size of large viruses. But most scientists do not consider viruses to be independent living organisms because they cannot reproduce on their own. Viruses hijack another organism's biological machinery to replicate.

This could be argued forever but hijacking and replicating sound very life-like to me. Viruses do things rocks can't do. Deliberately doing anything at all seems like a definition of life.

It's not that they don't consider viruses to be lifeforms, they merely don't consider them to be independent lifeforms, meaning that viruses could not be found to thrive on their own without the presence of other life. Scientists still consider viruses to be lifeforms.

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Message 490986 - Posted: 26 Dec 2006, 18:17:12 UTC - in response to Message 490950.
Last modified: 26 Dec 2006, 18:17:27 UTC

It's not that they don't consider viruses to be lifeforms, they merely don't consider them to be independent lifeforms, meaning that viruses could not be found to thrive on their own without the presence of other life. Scientists still consider viruses to be lifeforms.


Is anybody reading this an independent lifeform?

Without the presence of other life, I (and other creatures too) would die of starvation.
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Message 491280 - Posted: 27 Dec 2006, 3:14:34 UTC - in response to Message 490986.
Last modified: 27 Dec 2006, 3:15:50 UTC

It's not that they don't consider viruses to be lifeforms, they merely don't consider them to be independent lifeforms, meaning that viruses could not be found to thrive on their own without the presence of other life. Scientists still consider viruses to be lifeforms.


Is anybody reading this an independent lifeform?

Without the presence of other life, I (and other creatures too) would die of starvation.

Agreed. The only things I can think of that we ingest that have never lived are water and minerals like salt and iron. Everything else is a life form and our lives depend on eating them. We're totally dependent on the presence of other life forms including those that live inside us.

The biggest difference is that we know how to accessorize with condiments :-)
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Message 491349 - Posted: 27 Dec 2006, 3:35:50 UTC - in response to Message 491280.

The biggest difference is that we know how to accessorize with condiments :-)


haha... Yes that and also that we tend to kill the other life-forms before ingesting them.

It occurs to me know that almost all life is dependant on other life-forms to survive. Whether it be as part of a healthy diet or as the bacterial activity the digests the food in the stomach, there is much co-dependance.
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Message 491761 - Posted: 27 Dec 2006, 17:54:48 UTC - in response to Message 490894.

That also is the size of large viruses. But most scientists do not consider viruses to be independent living organisms because they cannot reproduce on their own. Viruses hijack another organism's biological machinery to replicate.

This could be argued forever but hijacking and replicating sound very life-like to me. Viruses do things rocks can't do. Deliberately doing anything at all seems like a definition of life.


I can't reproduce on my own, but I still consider myself to be an independent life form (depending on the technical meaning of the term independent in this context).

I'm not sure about the use of the word deliberate here, it sounds too much like conciousness to me. I don't believe plants choose to do anything (by deliberation or even by instinct), they can automatically respond to their environment in seemingly clever ways, but these seemingly clever ways came out of a long evolutionary process. The plants that are less well adapted to their particular current habitats will not reproduce as much as the more well adapted, as the 'better' plants begin to take over their habitat, food supplies, etc.
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Message boards : Science (non-SETI) : Pond scum may hold tiniest known life-form

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