“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.
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.
4.1 billion years ago, there were oceans on Venus as well. Just saying
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.
Quote from: Star One on 09/01/2016 06:37 AMMakes 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...
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.
Quote from: redliox on 09/01/2016 10:54 AMI'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.
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!
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.
Quote from: Star One on 09/01/2016 06:37 AMMakes 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/
Quote from: Star One on 09/03/2016 07:07 AMThere 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.
Quote from: jgoldader on 09/03/2016 01:37 PMQuote from: Star One on 09/03/2016 07:07 AMThere 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?
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.
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.
I may be mistaken, but if I understand correctly prions do not require nucleic acids to replicate. Prions are proteins that, while chemically identical to healthy proteins, are folded differently than their healthy counterparts. Their misfolded morphology becomes a template which causes healthy proteins to misfold, thus replicating the prion.
I may be mistaken, but if I understand correctly prions do not require nucleic acids to replicate.
Fundamental dogma of biology, man. DNA -> RNA -> Protein. Prions interfere with the last step to amplify their variation, but without the production machinery they have nothing to replicate from.
In my (very non-medical) thinking, I view prions as akin to a virus, in that they can't reproduce on their own. They "take over" properly folded proteins as viruses take over a normal cell's mechanisms in order to reproduce. Maybe, they are just in a class by themselves.On tests for finding RNA life--yes, IIRC Ward discusses this, and says while RNA life might have been here first, and may still be here, because of the requirement of DNA for "life as we know it," researchers look for DNA. Ward's "Life As We Do Not Know It" and his other book "Rare Earth" (co-authored with Don Brownlee, who taught one of the best classes I ever took) are very good reading indeed for folks interested in the possibility of life elsewhere. But fair warning, Rare Earth is a bit soul-crushing for those who want intelligent life to be common.
Ward's "Life As We Do Not Know It" and his other book "Rare Earth" (co-authored with Don Brownlee, who taught one of the best classes I ever took) are very good reading indeed for folks interested in the possibility of life elsewhere. But fair warning, Rare Earth is a bit soul-crushing for those who want intelligent life to be common.
Quote from: jgoldader on 09/05/2016 10:29 AMWard's "Life As We Do Not Know It" and his other book "Rare Earth" (co-authored with Don Brownlee, who taught one of the best classes I ever took) are very good reading indeed for folks interested in the possibility of life elsewhere. But fair warning, Rare Earth is a bit soul-crushing for those who want intelligent life to be common.Mind you "Rare Earth" is very dated now. Something he acknowledges.
Quote from: Dalhousie on 09/06/2016 03:36 AMQuote from: jgoldader on 09/05/2016 10:29 AMWard's "Life As We Do Not Know It" and his other book "Rare Earth" (co-authored with Don Brownlee, who taught one of the best classes I ever took) are very good reading indeed for folks interested in the possibility of life elsewhere. But fair warning, Rare Earth is a bit soul-crushing for those who want intelligent life to be common.Mind you "Rare Earth" is very dated now. Something he acknowledges.Oh, the book is getting on in years, yes. It's a darned good read, though. I don't keep up on the geological stuff or paleobiology that much, so if that's dated, I'd not know. Their astronomy, as I recall it, is still sound. There was the follow-on book "Life and Death of Planet Earth" which might have updated the biology and geology some. It's unusual for *any* book to make me emotional, much less a science book, but both made me sad.
Quote from: jgoldader on 09/06/2016 11:18 PMQuote from: Dalhousie on 09/06/2016 03:36 AMQuote from: jgoldader on 09/05/2016 10:29 AMWard's "Life As We Do Not Know It" and his other book "Rare Earth" (co-authored with Don Brownlee, who taught one of the best classes I ever took) are very good reading indeed for folks interested in the possibility of life elsewhere. But fair warning, Rare Earth is a bit soul-crushing for those who want intelligent life to be common.Mind you "Rare Earth" is very dated now. Something he acknowledges.Oh, the book is getting on in years, yes. It's a darned good read, though. I don't keep up on the geological stuff or paleobiology that much, so if that's dated, I'd not know. Their astronomy, as I recall it, is still sound. There was the follow-on book "Life and Death of Planet Earth" which might have updated the biology and geology some. It's unusual for *any* book to make me emotional, much less a science book, but both made me sad. It was the astronomy part that was most dated, as it still assumed that planetary systems are rare (unfortunate given the exoplanet revolution that was already underway when it was written). if you like Ward's writing, you should try Gorgon, all about the amazing mammal-like reptiles of the Permian and the Permo-Triassic extinction.
I am surprised that nobody has mentioned ALH84001 yet. There is still debate about whether the meteorite contains biogenic fossils or not.
Are we saying that life on Mars never progressed beyond the RNA stage?
Quote from: high road on 09/04/2016 06:43 PMAren't (some) viruses RNA life?The kind of RNA life biologists are interested in is the kind that doesn't require enzymes made from protein. i.e., the "RNA World" hypothesis is that the enzymatic activity required for life is possible using self catalysed reactions.
Those fossil candidates seem to impress many, compared to the slow consensus of the 3.5 Ga stromatolites. So maybe we will see references to 3.8 Ga fossils soon.
if you like Ward's writing, you should try Gorgon, all about the amazing mammal-like reptiles of the Permian and the Permo-Triassic extinction.
The ALH84001 meteorite is 4.4 Ga, which is before the martian 4.1 - 3.8 Ga habitable window that is currently considered.
If I had to pick a single scientific question to know the answer to, it would be the Fermi paradox. It would be interesting (yet probably not terribly useful) to know how the universe got started, and likewise to know how life got going here. But understanding the Fermi paradox is all about the future. You can have a solution to the Fermi paradox if the universe is full of algae, but with ourselves, as intelligent animals, being unique. That would also make me sad, and I hope it's not the case, but my opinion isn't relevant to what's actually going on.
But not everyone is convinced by the new study, not least Frances Westall, an expert on ancient fossil bacteria at the French national centre for scientific research. “The thing that bothers me most about these structures is the fact that they all seem to be extremely oriented. They are parallel to each other and microbes don’t grow parallel to each other,” she said.Westall said it remains possible that the haematite structures were formed as a result of the high temperatures and pressures experienced by metamorphic rocks. What’s more, she points out, the newly discovered filaments are far larger than the oldest known well-preserved microbial filaments previously found in 3.33bn-year-old rocks – a surprise given the lack of oxygen in the environment in which the newly proposed fossils are thought to have originated. “In an environment without oxygen, microbes grow – but they grow very slowly and they are small,” she said.“What I am not saying is that there could not have been life at 3.8bn years ago,” Westall added. “But in rocks that have been so altered, like these have been, I think that morphological traces are unlikely to remain.”Others, too, remain cautious, if more optimistic. David Emerson, a geomicrobiologist and expert in modern iron-oxidising bacteria at the Bigelow Laboratory for Ocean Sciences in the US said that the structures do not look like what would be expected from modern bacteria, but that he found it compelling that filaments are found in groups, suggesting a colony of microbes. But, he added, “I don’t think there is a smoking gun here that says this is clearly biological.”
Here's an update on this matter and a note of caution is struck.World's oldest fossils found in Canada, say scientistsQuoteBut not everyone is convinced by the new study, not least Frances Westall, an expert on ancient fossil bacteria at the French national centre for scientific research. “The thing that bothers me most about these structures is the fact that they all seem to be extremely oriented. They are parallel to each other and microbes don’t grow parallel to each other,” she said.Westall said it remains possible that the haematite structures were formed as a result of the high temperatures and pressures experienced by metamorphic rocks. What’s more, she points out, the newly discovered filaments are far larger than the oldest known well-preserved microbial filaments previously found in 3.33bn-year-old rocks – a surprise given the lack of oxygen in the environment in which the newly proposed fossils are thought to have originated. “In an environment without oxygen, microbes grow – but they grow very slowly and they are small,” she said.“What I am not saying is that there could not have been life at 3.8bn years ago,” Westall added. “But in rocks that have been so altered, like these have been, I think that morphological traces are unlikely to remain.”Others, too, remain cautious, if more optimistic. David Emerson, a geomicrobiologist and expert in modern iron-oxidising bacteria at the Bigelow Laboratory for Ocean Sciences in the US said that the structures do not look like what would be expected from modern bacteria, but that he found it compelling that filaments are found in groups, suggesting a colony of microbes. But, he added, “I don’t think there is a smoking gun here that says this is clearly biological.”https://www.theguardian.com/science/2017/mar/01/worlds-oldest-fossils-found-canada-say-scientists-quebec-haematite-377bn-428bn-years
The best answer to the Fermi Paradox that I've come across states simply that once a technological species advances enough to be able to use fusion power, then a planetary gravity well is no longer attractive to them. A planet cannot easily provide the variety and availability of raw materials that the small icy bodies can, so that advanced life is more likely to inhabit the Oort Cloud equivalents of star systems. A dominant, advanced species can expand to populate an entire galaxy without bothering itself with any of the inner planets.
An entire solar system of raw materials is an awful lot. It's not clear to me that the need for more space to live in or raw materials to consume alone would motivate such a civilization(or many civilizations) to expand across an entire galaxy given almost any amount of time.
Quote from: llanitedave on 09/08/2016 04:12 AMThe best answer to the Fermi Paradox that I've come across states simply that once a technological species advances enough to be able to use fusion power, then a planetary gravity well is no longer attractive to them. A planet cannot easily provide the variety and availability of raw materials that the small icy bodies can, so that advanced life is more likely to inhabit the Oort Cloud equivalents of star systems. A dominant, advanced species can expand to populate an entire galaxy without bothering itself with any of the inner planets.When I first read about Hair and Hedman's work and the Fermi paradox, it occurred to me that there is a very simple explanation, and that is that FTL travel and communication is not possible in this universe. What Hair and Hedman talk about is completely true and does not rely on FTL at all from a topical perspective, but the motivation to expand and build such a galactic empire doesn't exist.Think about it, our galaxy is over 100,000 light years in diameter. The closest star to us is 4 light years away. What motivation does this empire have to exist if there's a practical upper limit of 0.1c for travel and 1c for comms? No trade, no military support, and not even the ability to have a central authority to drive any kind of imperative(such as colonize the entire galaxy.) Let's say this authority is "conveniently" located near sag A*, it still takes over 50,000 years for any new directive to propagate, and that's assuming no response is necessary. Let's say our friends at Proxima Centauri need something from us. We won't even know for 4 years, and it'll take another 40 for us to get it there.An entire solar system of raw materials is an awful lot. It's not clear to me that the need for more space to live in or raw materials to consume alone would motivate such a civilization(or many civilizations) to expand across an entire galaxy given almost any amount of time.
Just a bit of context: This time is before the presumed 'Late Heavy Bombardment' that theory says created most of the Moon's (and presumably Mars's too) crater fields, which was about 3.8Gya. It has been previously assumed that this would have basically liquefied Earth's surface. Taking this into consideration, it is probably going to be statistically difficult to find more samples on Earth, let alone the other terrestrial planets.
Quote from: Req on 03/02/2017 03:25 AMQuote from: llanitedave on 09/08/2016 04:12 AMThe best answer to the Fermi Paradox that I've come across states simply that once a technological species advances enough to be able to use fusion power, then a planetary gravity well is no longer attractive to them. A planet cannot easily provide the variety and availability of raw materials that the small icy bodies can, so that advanced life is more likely to inhabit the Oort Cloud equivalents of star systems. A dominant, advanced species can expand to populate an entire galaxy without bothering itself with any of the inner planets.When I first read about Hair and Hedman's work and the Fermi paradox, it occurred to me that there is a very simple explanation, and that is that FTL travel and communication is not possible in this universe. What Hair and Hedman talk about is completely true and does not rely on FTL at all from a topical perspective, but the motivation to expand and build such a galactic empire doesn't exist.Think about it, our galaxy is over 100,000 light years in diameter. The closest star to us is 4 light years away. What motivation does this empire have to exist if there's a practical upper limit of 0.1c for travel and 1c for comms? No trade, no military support, and not even the ability to have a central authority to drive any kind of imperative(such as colonize the entire galaxy.) Let's say this authority is "conveniently" located near sag A*, it still takes over 50,000 years for any new directive to propagate, and that's assuming no response is necessary. Let's say our friends at Proxima Centauri need something from us. We won't even know for 4 years, and it'll take another 40 for us to get it there.An entire solar system of raw materials is an awful lot. It's not clear to me that the need for more space to live in or raw materials to consume alone would motivate such a civilization(or many civilizations) to expand across an entire galaxy given almost any amount of time.Motivation is indeed the critical piece, for exactly these reasons.What you need to do is replace "first evolved species" with "first evolved species that is inherently wired to expand" and the then argument remains the same.So yeah, the first 1000 species may not propagate due to lack of motivation, but #1001 will, and then you can overrun the galaxy pretty quickly even with 0.01c or 0.001c
It was around 1.6 billion years ago that a community of small, bright red, plantlike life-forms, flitting around in a shallow pool of prehistoric water, were etched into stone until the end of time. Or at least until a team of Swedish researchers chipped their fossilized remnants out of a sedimentary rock formation in central India.Research published this week in PLoS Biology suggests this collection of ancient, newly analyzed fossils—unearthed a few years back—are in all likelihood red algae. If that proves true, it would imply that complex, multicellular life evolved a lot earlier than previously thought—and that the evolutionary family tree of life on Earth might need a major pruning.
An international team of researchers discovered that inorganic chemicals can self-organize into complex structures that mimic primitive life on Earth.Florida State University Professor of Chemistry Oliver Steinbock and Professor Juan Manuel Garcia-Ruiz of the Consejo Superior de Investigaciones Cientificas (Spanish National Research Council) in Granada, Spain published an article in Wednesday's edition of Science Advances that shows fossil-like objects grew in natural spring water abundant in the early stages of the planet. But they were inorganic materials that resulted from simple chemical reactions.This complicates the identification of Earth's earliest microfossils and redefines the search for life on other planets and moons."Inorganic microstructures can potentially be indistinguishable from ancient traces of life both in morphology and chemical composition," Garcia-Ruiz said.Scientists had seen hints of this in past lab work, but now through Steinbock and Garcia-Ruiz's research, it is clear that this also happened in nature.
Life on Earth could be nearly four billion years old, new fossil evidence suggests.Researchers analysed rocks found in Saglek in northern Labrador, Canada, which were dated to at least 3.95 billion years ago. At that time, the Earth was still relatively young – it was formed about 4.5 billion years ago – and was probably still being bombarded by asteroids.Tests on grains of graphite found in the sedimentary rocks found that they had been produced by living organisms, thought to be single-celled plants capable of photosynthesis.
The discovery has two implications for the search for extra-terrestrial life. One is that the earlier life is found to have begun on Earth, the more likely it is that it will be found elsewhere.The other is that it increases the amount of time it took for complex life and intelligent life to form on Earth, which might mean that is a relatively rare occurrence – although little can be deduced from a sample size of oneIt is thought photosynthesising life would have arisen after a more primitive form, which if correct would push the date of the origin of life on Earth back further. “It looks like they [life-forms] arose pretty much as soon as they could,” Dr Sutton said.
I would have linked to the paper but the link isn’t working. I wonder if they’ve jumped the gun on this and the paper hasn’t been published yet?
Quote from: Star One on 09/27/2017 11:38 AMI would have linked to the paper but the link isn’t working. I wonder if they’ve jumped the gun on this and the paper hasn’t been published yet?I guess is was supposed to be embargoed until this evening, as is usual for articles that will be published in Nature on Thursday.
Not often on this forum when a microbiologist like me has something substantive to contribute! First, let's see what the data really are here when the paper is released. It's pretty common for leaked press reports to mangle things. Second, it's alway good to be a bit skeptical when people are pushing up against the limits of what can reasonably be inferred from the data. It sounds like they have found chemical signatures suggestive of biological origin, which is not the same as, say, actual microfossils. That said, there is some value in considering how long things took to appear on Earth relative to the "lifespan" of sun-like stars. Signs of bacterial life can be found in rocks almost all the way back to when the Earth cooled enough to allow liquid water. On the other hand, eukaryotic cells (which have much more complex internal structures) do not appear until more than a billion years after that, and abundant, complex multicellular eukaryotes take more than a billion years after that. Technological intelligence takes "only" a few hundred million years after that (leaving aside the question of what steps come _after_ us). And as the Sun continues to brighten over time, in less than a couple billion years more, the Earth will no longer be able to sustain liquid water, so in the one example we have to work with, Earth will have spent most of its time in the Habitable Zone populated with single-celled life, but technological intelligence was a bit of a close call. Hope is that by studying the chemistry of promising targets over the next few decades (Mars subsurface, Europa, Titan, Enceladus, and perhaps spectroscopic analysis of extrasolar planets), we'll get a better idea of how likely life might be elsewhere.
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