Author Topic: Oldest fossils ever discovered raises question of life on Mars  (Read 9277 times)

Offline Star One

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Makes you wonder if this indicates that as soon as a planet finishes forming, that providing conditions are right life will spring up ASAP. Considering that it's now believed life could have started on Earth 4.1 billion years ago, so very early on.

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“Up until now the oldest stromatolites have been from Western Australia and they are roughly 3,500 million (3.5bn) years [old],” said Clark Friend, an independent researcher and co-author of the research. “What we are doing is pushing the discovery of life earlier in Earth’s history.”

The discovery, says Friend, also raises questions about the possibility of life on other planets.

“If we have got life at 3,700 million (3.7 bn) years on Earth, did it exist on other planets - because Mars, for example, 3,700 million years ago was wet,” he said.

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Dartnell agrees that the discovery could help researchers explore whether life was once present on other planets. “The Martian surface today is very cold and dry, but around the time that these ancient layered rocks formed in Greenland, Mars was itself a much warmer and wetter, and thus habitable planet,” he said. While finding stromatolites with robotic landers or even manned missions is likely to be challenging, says Dartnell, if stromatolites are present, they could offer a wealth of information. “On Mars, we’d expect stromatolites, even as old as 3.5-3.8 billion years, to be better preserved than on Earth as Mars hasn’t experienced geological processes like plate tectonics,” he said.

https://www.theguardian.com/science/2016/aug/31/oldest-fossils-on-earth-discovered-in-37bn-year-old-greenland-rocks-stromatolites

Here's the Nature paper.

http://www.nature.com/nature/journal/vaop/ncurrent/full/nature19355.html
« Last Edit: 09/01/2016 06:55 AM by Star One »

Offline high road

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4.1 billion years ago, there were oceans on Venus as well. Just saying  ;)

Offline ugordan

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4.1 billion years ago, there were oceans on Venus as well. Just saying  ;)

Maybe.  Even if you ignore the hellish environment any attempt at surface exploration would encounter, since Venus does not have plate tectonics but is thought to overturn its entire crust periodically, finding any fossils might be a challenge.

Offline Bob Shaw

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The best place to look for Venus fossils will be anywhere but Venus, where the weather and geology are terrible. Ice caps, glaciers and shadowed points on Earth, the Moon and Mercury can preserve and sort incoming material better than any other locations. Rather than looking for needles in a haystack, you seek fossil-bearing meteorites among those to be found on the 'shores' of ice where it has sublimated away. People do this already on Earth, and it wouldn't be impossible to do this robotically elsewhere.

Speaking of which, an upside of Global Warming here may be the deposition of meteorites as glaciers retreat - though, oddly, I've never seen any mention of meteorites in moraines etc - perhaps early Iron Age people grabbed all the irons!

Offline Bob Shaw

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Makes you wonder if this indicates that as soon as a planet finishes forming, that providing conditions are right life will spring up ASAP. Considering that it's now believed life could have started on Earth 4.1 billion years ago, so very early on.


The flip side of that is, will we find that all local life is/was a close relative? A lot of stuff has been exchanged between the bodies of the Solar System as a result of impacts, and these used to be far larger and more common than nowadays. Now, as for exoplanets...

Offline Star One

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Makes you wonder if this indicates that as soon as a planet finishes forming, that providing conditions are right life will spring up ASAP. Considering that it's now believed life could have started on Earth 4.1 billion years ago, so very early on.


The flip side of that is, will we find that all local life is/was a close relative? A lot of stuff has been exchanged between the bodies of the Solar System as a result of impacts, and these used to be far larger and more common than nowadays. Now, as for exoplanets...

There was some theory I saw proposed in a New Scientist article last year that there may be a direction of travel in the spread of life in the Milky Way. But obviously you have to find other life first.

Offline redliox

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I'm sure there could be fossils on Mars. This discovery just says it is possible. There is more likely to be fossils on Mars as opposed to living organisms; if anything it is a matter of finding where to look first.
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Offline Star One

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I'm sure there could be fossils on Mars. This discovery just says it is possible. There is more likely to be fossils on Mars as opposed to living organisms; if anything it is a matter of finding where to look first.

The only place I could see life surviving on Mars is in its caves and caverns.

Offline kevin-rf

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I'm sure there could be fossils on Mars. This discovery just says it is possible. There is more likely to be fossils on Mars as opposed to living organisms; if anything it is a matter of finding where to look first.

The only place I could see life surviving on Mars is in its caves and caverns.

Extreme life on earth is found underground in rock without any caves and caverns. When drilling for oil, they find microorganisms in the sludge that comes out of the drill holes. The drill holes go very deep. The same can be true on Mars. 
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Offline Dalhousie

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Speaking of which, an upside of Global Warming here may be the deposition of meteorites as glaciers retreat - though, oddly, I've never seen any mention of meteorites in moraines etc - perhaps early Iron Age people grabbed all the irons!

Probably too many other rocks in moraines.  Here's one from a retreating glacier in Ladakh.  Good lucking finding a meteorite in that lot! ;)
"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Offline Dalhousie

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The best place to look for Venus fossils will be anywhere but Venus, where the weather and geology are terrible. Ice caps, glaciers and shadowed points on Earth, the Moon and Mercury can preserve and sort incoming material better than any other locations. Rather than looking for needles in a haystack, you seek fossil-bearing meteorites among those to be found on the 'shores' of ice where it has sublimated away. People do this already on Earth, and it wouldn't be impossible to do this robotically elsewhere.

It's a good idea, although as I understand it, the high gravity and thick atmosphere make it very difficult to eject material from Venus.  The lack of atmosphere on Mercury and the Moon mean that meteorites arrive there with velocities of km/s, which isn't good for preservation.  You need an atmosphere to lose them down.

Also to consider is that meteorites have a life time in space.  No Mars meteorite has yet been discovered which was ejected more than 20 million years ago.

So this leaves finding a very ancient meteorite from Venus on Earth in an ancient sedimentary succession.  Not possible, but extremely improbable.  Very few meteorites in ancient successions are known, although the are occasionally recognised.
"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Offline Bynaus

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Makes you wonder if this indicates that as soon as a planet finishes forming, that providing conditions are right life will spring up ASAP. Considering that it's now believed life could have started on Earth 4.1 billion years ago, so very early on.

Well, if you take the age of the fossils, 3.8 Ga, then it's not that fast. Almost the same amount of time between the formation of the planet and the first fossils as between the Cambrian explosion and today... And Earth was apparently habitable (cool, with running water and possibly an ocean) quite early on (=~4.4 Ga).

Offline Star One

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Makes you wonder if this indicates that as soon as a planet finishes forming, that providing conditions are right life will spring up ASAP. Considering that it's now believed life could have started on Earth 4.1 billion years ago, so very early on.

Well, if you take the age of the fossils, 3.8 Ga, then it's not that fast. Almost the same amount of time between the formation of the planet and the first fossils as between the Cambrian explosion and today... And Earth was apparently habitable (cool, with running water and possibly an ocean) quite early on (=~4.4 Ga).
There was an article recently putting forward the view in a very recent New Scientist that life could have arisen on Earth multiple times.

https://www.newscientist.com/article/mg23130870-200-life-evolves-so-easily-that-it-started-not-once-but-many-times/
« Last Edit: 09/03/2016 07:10 AM by Star One »

Offline redliox

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There was an article recently putting forward the view in a very recent New Scientist that life could have arisen on Earth multiple times.

https://www.newscientist.com/article/mg23130870-200-life-evolves-so-easily-that-it-started-not-once-but-many-times/

There could be some truth to it, but the problem is it would have happened so far back that the heavy bombardment coupled with plate tectonics wiped out the evidence...save perhaps some genetic information in mitochondria and ancient cells.  We may find more evidence for the evolution of ancient life by studying DNA as opposed to fossils in some cases.

On Mars, there may be a chance, if it had life or Earthly-borne life, of it being preserved in a few regions.
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Offline high road

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Not necessarily.  Life could be emerging all the time. Going from simple life to complex life seems to be very difficult, as it took the better part of the lifetime of the earth to do it once. So new protolifeforms could be getting devoured by more developed life before it gets a chance to evolve into a successful creature.

Offline jgoldader

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There was an article recently putting forward the view in a very recent New Scientist that life could have arisen on Earth multiple times.

https://www.newscientist.com/article/mg23130870-200-life-evolves-so-easily-that-it-started-not-once-but-many-times/

Ahh, New Scientist.

It's certainly plausible that there were many biogenesis events on Earth, but all evidence (DNA phylogeny) points towards one completely dominating to the extent that those organisms wiped out all the others.

One interesting hypothesis involves RNA-based life, which is possible but for which we've really never looked.  It is described in Peter Ward's book "Life As We Do Not Know It." We could have a shadow biosphere all around us that our DNA bias has caused us to ignore.
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Offline Dalhousie

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There was an article recently putting forward the view in a very recent New Scientist that life could have arisen on Earth multiple times.

https://www.newscientist.com/article/mg23130870-200-life-evolves-so-easily-that-it-started-not-once-but-many-times/

Ahh, New Scientist.

It's certainly plausible that there were many biogenesis events on Earth, but all evidence (DNA phylogeny) points towards one completely dominating to the extent that those organisms wiped out all the others.

One interesting hypothesis involves RNA-based life, which is possible but for which we've really never looked.  It is described in Peter Ward's book "Life As We Do Not Know It." We could have a shadow biosphere all around us that our DNA bias has caused us to ignore.

RNA life probably preceded DNA life, and was probably ancestral to it.

I would have thought the RNA life, if still extant would be visible through ribosomal RNA testing of soils etc.  But I will have to read Ward's book, he is a stimulating writer (and speaker for that matter).
"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Offline Star One

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It rather seems like the discovery of evidence concerning fossil life on Mars would be much less surprising than finding current life on the planet.

Offline Mongo62

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I am surprised that nobody has mentioned ALH84001 yet. There is still debate about whether the meteorite contains biogenic fossils or not. In my opinion, some of the evidence is very hard to explain by non-biological means. So it's quite possible that we already have fossil Martian life in our hands.

Offline high road

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There was an article recently putting forward the view in a very recent New Scientist that life could have arisen on Earth multiple times.

https://www.newscientist.com/article/mg23130870-200-life-evolves-so-easily-that-it-started-not-once-but-many-times/

Ahh, New Scientist.

It's certainly plausible that there were many biogenesis events on Earth, but all evidence (DNA phylogeny) points towards one completely dominating to the extent that those organisms wiped out all the others.

One interesting hypothesis involves RNA-based life, which is possible but for which we've really never looked.  It is described in Peter Ward's book "Life As We Do Not Know It." We could have a shadow biosphere all around us that our DNA bias has caused us to ignore.

RNA life probably preceded DNA life, and was probably ancestral to it.

I would have thought the RNA life, if still extant would be visible through ribosomal RNA testing of soils etc.  But I will have to read Ward's book, he is a stimulating writer (and speaker for that matter).

Aren't (some) viruses RNA life? Even on that scale, life forms that are able to interact and take what they need to survive from life forms that dominate the planet, would have a huge competitive advantage over alternative RNA life that would have to compete without being able to profit from that dominant life form.

Or alternatively, such life would fill up a niche where it can survive because it does not have to interact with us to survive, so by definition it would not be found anywhere near our kind of life. And it would have an evolutionary benefit in keeping 'us' away, so it's probably quite toxic to us.

Think about it: something in a location harder to find, less likely to be habitable (to our preconceptions) and very likely less identifiable as life than snotites. We wouldn't even know where to start looking.

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