3.48 billion years old life

[neufer]

Evidence of 3.5-billion-year-old bacterial ecosystems may be earliest sign of life on Earth
FoxNews.com, November 13, 2013

[b][color=#0000FF]A rock surface displaying polygonal oscillation cracks in the 3.48 billion years old Dresser Formation, Pilbara region, Western Australia. (Nora Noffke/Carnegie Institute)[/color][/b]

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<<Scientists have discovered what may be the earliest sign of life on Earth. Remains of nearly 3.5-billion-year-old bacteria has been found in north-west Australia. Evidence of the never-before-seen bacteria was found in sedimentary rocks in the remote Pilbara region, home to the world's oldest rock formations. "There was plenty of life from the 3.4 and 3.43 billion-year-old mark – this is pushing it further back," researcher David Wacey, from the University of Western Australia told The Telegraph.

While there are no cells from the microbially induced sedimentary structures (MISS) to be studied under the microscope, scientists observed the marks left behind created by large clusters of microbes. "We don't see the microbe themselves but we large scale structures that the microbes constructed before they died," Wacey said.

Other life forms have been studied in the region before including microfossils of bacteria indicating the Pilbara region holds many clues to the early evolution of life. The discovery "helps with our understanding of when life first evolved and what sort of environment it evolved in and putting firm dates on when some pretty important things happened," Wacey explained. "Ultimately, we are looking for when that soup of chemicals became something that could be called life." The findings are published in the journal Astrobiology.>>

[Chris Peterson]

Evidence of 3.5-billion-year-old bacterial ecosystems may be earliest sign of life on Earth

What I found interesting on first reading about this is that the result is being published as astrobiology. I've also been reading some interesting new work about nitrogen cycles, with astrobiological work using Earth analogs.

In fact, understanding the nature of the earliest life on Earth, when this planet didn't look like anything we recognize today as a likely candidate for supporting life, really is better described as astrobiology than anything else. It demonstrates the value of astrobiology as a separate, focused discipline.

[rstevenson]

After which comment, I must suggest perusing this cartoon...

Rob

[Nitpicker]

I agree with what you say Chris. (And awesome cartoon rstevenson -- I missed my calling.)

On a separate note, it may or may not be the earliest sign of life on Earth. (I wish journalists would stop overstating and distorting evidence.) The fact that similar signs of prokaryote life have been detected in places like Canada and Greenland and others, and dated to around the same age (give or take a few hundred million years) is more interesting to me. The more (evidence) the merrier, I should think. I doubt we will ever be able to point to the earliest sign of life with certainty, nor do I think such precision is that important. The fact that these separate signs all date from a period "shortly" after the Late Heavy Bombardment (which is theorised based on independent, dated evidence, mainly extracted from the Apollo missions) is also a rather compelling piece of the puzzle. What would be truly shocking, would be a sign of life detected from before the LHB.

[Chris Peterson]

After which comment, I must suggest perusing this cartoon...

Amusing, but wrong. The point is, papers on the subject demonstrate that important discoveries are being made all the time. Life on another planet isn't the only discovery an astrobiologist can make.

[stephen63]

http://en.wikipedia.org/wiki/Late_Heavy_Bombardment

Of particular interest, Manfred Schidlowski argued in 1979 that the carbon isotopic ratios of some sedimentary rocks found in Greenland were a relic of organic matter. There was much debate over the precise dating of the rocks, with Schidlowski suggesting they were about 3800 Ma old, and others suggesting a more "modest" 3600 Ma. In either case it was a very short time for abiogenesis to have taken place, and if Schidlowski was correct, arguably too short a time. The Late Heavy Bombardment and the "re-melting" of the crust that it suggests provides a timeline under which this would be possible; life either formed immediately after the Late Heavy Bombardment, or more likely survived it, having arisen earlier during the Hadean. Recent studies suggest that the rocks Schidlowski found are indeed from the older end of the possible age range at about 3850 Ma, suggesting the latter possibility is the most likely answer.

Would it be possible for any fossil evidence to survive the LHB?

[Nitpicker]

After which comment, I must suggest perusing this cartoon...

Amusing, but wrong. The point is, papers on the subject demonstrate that important discoveries are being made all the time. Life on another planet isn't the only discovery an astrobiologist can make.

Regardless, celebrating happy hour in the lab is probably good for morale. Cheers!

[Chris Peterson]

Would it be possible for any fossil evidence to survive the LHB?

I think so. But there would be a lot less of it. There just isn't much material at all from earlier than the LHB. Almost everything was either melted at the time, or has been recycled since. So not only do you need a fossil to survive the LHB, but you need it to survive from the LHB to now. Between the two, I wouldn't be surprised if we never find earlier evidence of life, even if it existed.

[Nitpicker]

http://en.wikipedia.org/wiki/Late_Heavy_Bombardment

Of particular interest, Manfred Schidlowski argued in 1979 that the carbon isotopic ratios of some sedimentary rocks found in Greenland were a relic of organic matter. There was much debate over the precise dating of the rocks, with Schidlowski suggesting they were about 3800 Ma old, and others suggesting a more "modest" 3600 Ma. In either case it was a very short time for abiogenesis to have taken place, and if Schidlowski was correct, arguably too short a time. The Late Heavy Bombardment and the "re-melting" of the crust that it suggests provides a timeline under which this would be possible; life either formed immediately after the Late Heavy Bombardment, or more likely survived it, having arisen earlier during the Hadean. Recent studies suggest that the rocks Schidlowski found are indeed from the older end of the possible age range at about 3850 Ma, suggesting the latter possibility is the most likely answer.

Would it be possible for any fossil evidence to survive the LHB?

Not sure how one can say it is more likely that the signs of life detected by Schidlowski formed before the LHB, than after, simply because the more recent studies suggest the date to be closer to the end of the estimated timeframe of the LHB. I'd want to see something more than that. As best as I can tell from the somewhat contentious information on Wikipedia, the formation of liquid water and the oceans seems to have occurred at roughly the same time as the LHB, or slightly afterwards.

[Nitpicker]

If life developed on Earth before the LHB, and survived the LHB, but virtually all the evidence of the prior development was destroyed by the LHB, it would suddenly make it virtually impossible for astrobiologists (and others) to prove how life actually got started on Earth.

I think a lot of the work for astrobiologists must be in determining the full variety of ways in which life may develop, unlimited by the way that life actually started on Earth, however that was.

[geckzilla]

What if prions are the original life and all our proteins are the misfolded ones? Ok, that's ridiculous, but prions are fun an interesting to read about. https://en.wikipedia.org/wiki/Prion

[Nitpicker]

What if prions are the original life and all our proteins are the misfolded ones? Ok, that's ridiculous, but prions are fun an interesting to read about. https://en.wikipedia.org/wiki/Prion

Sounds logically impossible, since prions require properly folded proteins to hijack, in order to propagate, and proteins don't need prions.

Q: What came first the prion or the protein?
A: The protein.

But thanks, I never knew about prions before today.

[geckzilla]

Yes, one of those things that acts like life but isn't life at all. Still, I think studying how things go wrong can lead to greater understanding of how life itself works. They are rather scary, though.

[neufer]

What if prions are the original life and all our proteins are the misfolded ones? Ok, that's ridiculous, but prions are fun an interesting to read about. https://en.wikipedia.org/wiki/Prion

• Are we descended from Jovial prions

<<The study from Scripps Florida in Jupiter shows that prions can develop large numbers of mutations at the protein level and, through natural selection, these mutations can eventually bring about such evolutionary adaptations as drug resistance, a phenomenon previously known to occur only in bacteria and viruses. These breakthrough findings also suggest that the normal prion protein -- which occurs naturally in human cells -- may prove to be a more effective therapeutic target than its abnormal toxic relation.>>

[BMAONE23]

Couldn't say Art, but you always seem to be a Jovial Person
jo·vi·al
/ˈjōvēəl/
adjective
adjective: jovial1. cheerful and friendly.
"she was in a jovial mood"
synonyms: cheerful, jolly, happy, cheery, good-humored, convivial, genial, good-natured, friendly, amiable, affable, sociable, outgoing; Moresmiling, merry, sunny, joyful, joyous, high-spirited, exuberant; chipper, chirpy, perky, bright-eyed and bushy-tailed, hail-fellow-well-met; formaljocund, jocose; datedgay; literaryblithe "his jovial manner"

antonyms: miserable

[Chris Peterson]

If life developed on Earth before the LHB, and survived the LHB, but virtually all the evidence of the prior development was destroyed by the LHB, it would suddenly make it virtually impossible for astrobiologists (and others) to prove how life actually got started on Earth.

Well, in science there is no such thing as proof. There is only evidence. The destruction of all evidence from before the LHB certainly does not make it impossible for us to know, with a high degree of confidence, how life started on Earth. At most, it may make it impossible to know if life existed before the LHB and survived, or developed only afterwards, or developed a second time afterwards. It doesn't have much impact on our ability to understand the mechanism or mechanisms involved in the development of life.

I think a lot of the work for astrobiologists must be in determining the full variety of ways in which life may develop, unlimited by the way that life actually started on Earth, however that was.

That is one thing that some astrobiologists work on. But the majority of astrobiology publications seem to involve work with Earth biology and geology. Studying the development of life on Earth is increasingly an astrobiological discipline.

[neufer]

Couldn't say Art, but you always seem to be a Jovial Person

• Jovial and Mercurial
  (Though not Venereal or Uranal).

[Beyond]

Jovial and Mercurial
(Though not Venereal or Uranal).

Being Jovial is priceless.
Being Mercurial is only worth a dime.
The other two, i wouldn't touch with a ten foot pole.
They are just not sublime.

[Nitpicker]

If life developed on Earth before the LHB, and survived the LHB, but virtually all the evidence of the prior development was destroyed by the LHB, it would suddenly make it virtually impossible for astrobiologists (and others) to prove how life actually got started on Earth.

Well, in science there is no such thing as proof. There is only evidence. The destruction of all evidence from before the LHB certainly does not make it impossible for us to know, with a high degree of confidence, how life started on Earth. At most, it may make it impossible to know if life existed before the LHB and survived, or developed only afterwards, or developed a second time afterwards. It doesn't have much impact on our ability to understand the mechanism or mechanisms involved in the development of life.

You're right. My logical statement (which may be proven or disproven) would have been improved with the word "know" in place of "prove". And I suppose that if we can understand at least some of the ways that life develops, then we can be more confident in knowing how life actually started on Earth, even with a lack of direct evidence of these first events.

[Ann]

I wholeheartedly agree that we should try to find out more about how life got started on Earth. It is of course very important to try to understand what the Earth was actually like at the time when life first appeared here. Our planet was, of course, almost unimaginably different from what the surface conditions and the biosphere of the Earth is like today.

In another thread, Chris mentioned the possibility that evolution acted on non-living compounds on the early Earth and changed them slowly over perhaps millions of years, until these compounds became more and more life-like. I find it astoundingly fascinating to think that there might not have been a clear demarcation line between non-life and life during the very earliest stages of life on Earth.

Ann

[neufer]

Click to play embedded YouTube video.

[Chris Peterson]

"Well, in science there is no such thing as proof."

I guess the world is flat after all, according to the at theory, because in science there is no such thing as proof. The scientific theory was at one time that earth was a sphere. I'm so disappointed.

The shape of the world is an observation, not a theory. How it got to be the shape we observe is a matter of theory, and as such can never be proven (although there is overwhelming evidence arguing for a particular conclusion).

Observation and theory are often confused. For example, evolution is not a theory, but an observation. Natural selection is a particular theory which was developed to explain the observation of evolution.

[geckzilla]

Observe now, if you will, the efficiency of the ban hammer script.

[Ann]

"Well, in science there is no such thing as proof."

I guess the world is flat after all, according to the at theory, because in science there is no such thing as proof. The scientific theory was at one time that earth was a sphere. I'm so disappointed.

The shape of the world is an observation, not a theory. How it got to be the shape we observe is a matter of theory, and as such can never be proven (although there is overwhelming evidence arguing for a particular conclusion).

Observation and theory are often confused. For example, evolution is not a theory, but an observation. Natural selection is a particular theory which was developed to explain the observation of evolution.

Thanks, Chris. You put that exceedingly well.

Ann