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Thread: A timescale for the origin and evolution of all of life on Earth?

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    A timescale for the origin and evolution of all of life on Earth?

    From Physorg:

    "A new study led by scientists from the University of Bristol has used a combination of genomic and fossil data to explain the history of life on Earth, from its origin to the present day.
    ...
    Using this approach we were able to show that the Last Universal Common Ancestor of all cellular life forms, 'LUCA', existed very early in Earth's history, almost 4.5 Billion years ago—not long after Earth was impacted by the planet Theia, the event which sterilised Earth and led to the formation of the Moon."


    Whoa, and wait a minute!

    The headline is misleading in that the "origin" of life isn't mentioned (I read only the news article and abstract), but where in the world did this LUCA come from, existing so near the origin of Earth? And then a billion year gap of sterilization and bombardment before relatives show up? What?! and many other questions...
    Where the telescope ends, the microscope begins. Which of the two has the greater view?

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    Quote Originally Posted by A.DIM View Post
    The headline is misleading in that the "origin" of life isn't mentioned (I read only the news article and abstract),
    Well, technically it's not wrong.

    The assertion is that the origin of all life on Earth is this critter.
    (Or, look at the inverse: there is no life on Earth that did not come from this critter.)

    That does not mean the critter itself does not also have an origin.

    Quote Originally Posted by A.DIM View Post
    And then a billion year gap of sterilization and bombardment before relatives show up?
    A billion year gap in the record. Since they are using a molecular clock, they can project backwards a billion years - through the era where we have no record - to a point nearer the Hadean.

    There no reason to suppose there weren't relatives in that billion year gap; they just don't appear in our records.


    Note: the numbers on my graph are arbitrary, and do not match the theory.
    molecular-clock.png
    Last edited by DaveC426913; 2018-Aug-21 at 04:33 PM.

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    Cannot yet get entire paper.


    http://www.nature.com/articles/s41559-018-0644-x

    Integrated genomic and fossil evidence illuminates life’s early evolution and eukaryote origin

    Holly C. Betts, Mark N. Puttick, James W. Clark, Tom A. Williams, Philip C. J. Donoghue & Davide Pisani
    Nature Ecology & Evolution (2018)

    Establishing a unified timescale for the early evolution of Earth and life is challenging and mired in controversy because of the paucity of fossil evidence, the difficulty of interpreting it and dispute over the deepest branching relationships in the tree of life. Surprisingly, it remains perhaps the only episode in the history of life where literal interpretations of the fossil record hold sway, revised with every new discovery and reinterpretation. We derive a timescale of life, combining a reappraisal of the fossil material with new molecular clock analyses. We find the last universal common ancestor of cellular life to have predated the end of late heavy bombardment (>3.9 billion years ago (Ga)). The crown clades of the two primary divisions of life, Eubacteria and Archaebacteria, emerged much later (<3.4 Ga), relegating the oldest fossil evidence for life to their stem lineages. The Great Oxidation Event significantly predates the origin of modern Cyanobacteria, indicating that oxygenic photosynthesis evolved within the cyanobacterial stem lineage. Modern eukaryotes do not constitute a primary lineage of life and emerged late in Earth’s history (<1.84 Ga), falsifying the hypothesis that the Great Oxidation Event facilitated their radiation. The symbiotic origin of mitochondria at 2.053–1.21 Ga reflects a late origin of the total-group Alphaproteobacteria to which the free living ancestor of mitochondria belonged.
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    Quote Originally Posted by A.DIM View Post
    where in the world did this LUCA come from, existing so near the origin of Earth? And then a billion year gap of sterilization and bombardment before relatives show up?
    LUCA would presumably have arisen from the evolution chemical processes but seemed to arise after the sterilisation event. How you sterilize something that doesn't have life... but possibly they refer to a resetting of the chemical environment, which would have included any previous life or complex chemical precursors.

    The Eukaryote lineage arises at a certain point, much later, by fusion of elements of other lineages. So it is not unreasonable that the Eubacteria and Archaebacteria could arise similarly from a point, possibly from fusion of lineages leading from LUCA, or similarly arising during that billion years, which have since become extinct.

    Even given the precision with which these events are being measured there is a time period on the order of hundred thousand years after the impact event and before LUCA, and we just don't know how fast these early evolution processes can take in suitable environments.

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    Quote Originally Posted by DaveC426913 View Post
    Well, technically it's not wrong.

    The assertion is that the origin of all life on Earth is this critter.
    (Or, look at the inverse: there is no life on Earth that did not come from this critter.)

    That does not mean the critter itself does not also have an origin.

    A billion year gap in the record. Since they are using a molecular clock, they can project backwards a billion years - through the era where we have no record - to a point nearer the Hadean.
    Fossils and molecular clocks have little or nothing to do with abiogenesis but I take your meaning.

    There no reason to suppose there weren't relatives in that billion year gap; they just don't appear in our records.
    I don't suppose there weren't relatives during the Hadean / LHB but the Earth during these time periods is thought to be inhospitable or uninhabitable for lawki. Should we suppose instead some form of extreme-lawki existed but the conditions erased any evidence? Should we suppose this life was transitional, linear even, between LUCA and the two lineages? Maybe we suppose it was actually LUCA's detritus or genetic material with which the two lineages utilized and evolved? Or maybe we suppose there's an outside influence repeatedly depositing material, if not LUCA itself?
    Ah, the mystery.
    Where the telescope ends, the microscope begins. Which of the two has the greater view?

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    Quote Originally Posted by transreality View Post
    LUCA would presumably have arisen from the evolution chemical processes but seemed to arise after the sterilisation event. How you sterilize something that doesn't have life...
    Indeed, the article's wording is curious: "Using this approach we were able to show that the Last Universal Common Ancestor of all cellular life forms, 'LUCA', existed very early in Earth's history, almost 4.5 Billion years ago—not long after Earth was impacted by the planet Theia, the event which sterilised Earth..."

    What is their meaning for "sterilised" here, I wonder, that the biochemical precursors and geophysical environment were, as you say "reset," and not conducive to lawki? I'm with you (i think) in that sterlization suggests some sort of precursor life.

    Even given the precision with which these events are being measured there is a time period on the order of hundred thousand years after the impact event and before LUCA, and we just don't know how fast these early evolution processes can take in suitable environments.
    Agreed.
    I recall The Feathered Onion, a book by a biologist who suggested 100 million years was too short a window for happenstance chemical environments to produce the biocomplexity found in the earliest known lawki. He focused on the period after the LHB before we find evidences for lawki, no doubt assuming Earth was uninhabitable during the Hadean. This genomic evidence seems to nearly close the window for abiogenesis-on-earth hypotheses. To me, it looks like LUCA might predate the Earth.
    Where the telescope ends, the microscope begins. Which of the two has the greater view?

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    Quote Originally Posted by A.DIM View Post
    This genomic evidence seems to nearly close the window for abiogenesis-on-earth hypotheses. To me, it looks like LUCA might predate the Earth.
    It is very hard to say that without a much better understanding of how they calibrated and determined the 'tick rate' of their clock. From their references they are using a Bayesian approach, which is only as good as the priors. And given the gaps in the record it may or may not be valid to use late complex life priors to estimate the evolution rates for early life.

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    There is a UT story today about a different study, using a different method, coming up with a different estimate.
    Universe Today

    In a new study by a team of Canadian researchers, the question of when life emerged on Earth is constrained using two approaches. By combining astrophysical and geophysical evidence with biosignatures in geological samples, they estimate that life emerged roughly 200 to 800 million years after Earth became habitable (ca. 3.7 billion years ago).
    The paper

    Abstract:
    Estimates of the time at which life arose on Earth make use of two types of evidence. First, astrophysical and geophysical studies provide a timescale for the formation of Earth and the Moon, for large impact events on early Earth, and for the cooling of the early magma ocean. From this evidence, we can deduce a habitability boundary, which is the earliest point at which Earth became habitable. Second, biosignatures in geological samples, including microfossils, stromatolites, and chemical isotope ratios, provide evidence for when life was actually present. From these observations we can deduce a biosignature boundary, which is the earliest point at which there is clear evidence that life existed. Studies with molecular phylogenetics and records of the changing level of oxygen in the atmosphere give additional information that helps to determine the biosignature boundary. Here, we review the data from a wide range of disciplines to summarize current information on the timings of these two boundaries. The habitability boundary could be as early as 4.5 Ga, the earliest possible estimate of the time at which Earth had a stable crust and hydrosphere, or as late as 3.9 Ga, the end of the period of heavy meteorite bombardment. The lack of consensus on whether there was a late heavy meteorite bombardment that was significant enough to prevent life is the largest uncertainty in estimating the time of the habitability boundary. The biosignature boundary is more closely constrained. Evidence from carbon isotope ratios and stromatolite fossils both point to a time close to 3.7 Ga. Life must have emerged in the interval between these two boundaries. The time taken for life to appear could, therefore, be within 200 Myr or as long as 800 Myr.
    I don't see how any of these estimates strongly support or contradict a non-terrestrial origin (panspermia). At best they may give an estimate on how easy or difficult it is for life to arise (particularly on Earth). But even then, if it takes a long while, then I can hear the arguments "see, it is hard for life to arise, therefore it must have come from elsewhere". Instead, we seem to have arguments in this thread "see, life arose very quickly, therefore it didn't have enough time to do so on Earth and must have come from elsewhere".
    Last edited by Swift; 2018-Sep-06 at 08:51 PM. Reason: typo
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    Quote Originally Posted by Swift View Post
    ... Instead, we seem to have arguments in this thread "see, life arose very quickly, therefore it didn't have enough time to do so on Earth and must have come from elsewhere".
    I've said no such thing and have seen no such arguments. We're questioning the results of the study I shared, and I thank you for your contribution.

    As it turns out, the paper you provided agrees with that in the OP: "They estimated a time of 4.29 Ga for the LUCA and 3.46 Ga for both the earliest branch point within Archaea and the earliest branch point within Bacteria. These dates are consistent with other types of evidence that we discussed above." p.26

    Of course uncertainties remain, and not least of which are the "tick rates" of molecular clocks used in these studies. I rarely, if ever, see Horizontal Gene Transfer discussed in these callibrations while I suspect it plays a more profound role in evolution than we realize.

    Still, the evidences we have here agree that LUCA and the habitability boundary could be as early as ~4.5Gyrs. If this is correct, then abiogenesis-on-earth hypotheses have a more narrow time period to explain themselves; Again, to me, it appears LUCA might, or could, predate Earth.
    Where the telescope ends, the microscope begins. Which of the two has the greater view?

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    Quote Originally Posted by A.DIM View Post
    ... abiogenesis-on-earth hypotheses have a more narrow time period to explain themselves....
    Shifting of burden of proof, noted.
    The facts, gentlemen, and nothing but the facts, for careful eyes are narrowly watching. Isaac Asimov

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    Quote Originally Posted by A.DIM View Post
    ....If this is correct, then abiogenesis-on-earth hypotheses have a more narrow time period to explain themselves....
    You seem to have a problem with "abiogenesis." You should read the thread Short Protein Could Have Existed in Early Life. Also compelling on this issue, I think, is Stuart Kauffman's book At Home In The Universe.
    Everyone is entitled to his own opinion, but not his own facts.

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    Quote Originally Posted by Cougar View Post
    You seem to have a problem with "abiogenesis." You should read the thread Short Protein Could Have Existed in Early Life. Also compelling on this issue, I think, is Stuart Kauffman's book At Home In The Universe.
    Thanks.
    I was managing a bookstore when that was published but read only excerpts; my mistake, I guess. And I did see that peptide thread, all three posts. But I'm unsure what "problem" you think I have or how either of those can correct my thinking. Please explain?
    Where the telescope ends, the microscope begins. Which of the two has the greater view?

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    Quote Originally Posted by A.DIM View Post
    I'm unsure what "problem" you think I have...
    Obvious bias...
    The facts, gentlemen, and nothing but the facts, for careful eyes are narrowly watching. Isaac Asimov

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    Quote Originally Posted by A.DIM View Post
    But I'm unsure what "problem" [with abiogenesis] you think I have or how either of those can correct my thinking. Please explain?
    Well, you questioned abiogenesis several times, but upon review, I see your questioning was based on the timescale put forward in the new study, which is, of course, a "legitimate" reason to question abiogenesis. On earth, at least. What are not legitimate reasons are simple incredulity or baseless beliefs, which are, unfortunately, much too common.
    Everyone is entitled to his own opinion, but not his own facts.

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    Quote Originally Posted by A.DIM View Post
    Thanks.
    I was managing a bookstore when that was published but read only excerpts....
    What was striking about Kauffman's book was how he showed that given a sufficient diversity of (granted, generic) molecules, the right kind of interactions for precursors of life was fairly inevitable. And quick.
    Everyone is entitled to his own opinion, but not his own facts.

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    Quote Originally Posted by Cougar View Post
    Well, you questioned abiogenesis several times, but upon review, I see your questioning was based on the timescale put forward in the new study, which is, of course, a "legitimate" reason to question abiogenesis. On earth, at least. What are not legitimate reasons are simple incredulity or baseless beliefs, which are, unfortunately, much too common.
    Here, you put "legitimate" in quotes and before you put "abiogenesis" in quotes; your point?

    I don't question whether or not abiogenesis occured. I question whether or not it occurred on Earth.


    What was striking about Kauffman's book was how he showed that given a sufficient diversity of (granted, generic) molecules, the right kind of interactions for precursors of life was fairly inevitable. And quick.
    Indeed, and I've opined the same: similar ingredients in similar environments gives similar results, and there's little reason to think it waited until Earth.
    Where the telescope ends, the microscope begins. Which of the two has the greater view?

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    Quote Originally Posted by A.DIM View Post
    ....similar ingredients in similar environments gives similar results, and there's little reason to think it waited until Earth.
    A reasonable argument. So life may exist elsewhere. But travel between star systems, regardless of method, would be a serious hurdle for panspermia to clear.
    Everyone is entitled to his own opinion, but not his own facts.

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    Quote Originally Posted by A.DIM View Post
    Here, you put "legitimate" in quotes and before you put "abiogenesis" in quotes; your point?

    I don't question whether or not abiogenesis occured. I question whether or not it occurred on Earth.




    Indeed, and I've opined the same: similar ingredients in similar environments gives similar results, and there's little reason to think it waited until Earth.
    So far, all we know is that similar ingredients in similar environments gives us similar chemicals. Building blocks.

    We don't know and have no way of estimating, how often those building blocks actually became built into the complex, actively reproducing molecular machinery now ubiquitous over, on, and in the planet.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by Cougar View Post
    A reasonable argument. So life may exist elsewhere. But travel between star systems, regardless of method, would be a serious hurdle for panspermia to clear.
    Agreed, and I've not suggested LUCA came from outside the solar system, only that it might predate Earth. There are potential mechanisms for interstellar panspermia (eg. oumuamua) but that is not the topic of this thread.
    Where the telescope ends, the microscope begins. Which of the two has the greater view?

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    Quote Originally Posted by Noclevername View Post
    So far, all we know is that similar ingredients in similar environments gives us similar chemicals. Building blocks.

    We don't know and have no way of estimating, how often those building blocks actually became built into the complex, actively reproducing molecular machinery now ubiquitous over, on, and in the planet.
    Yes, we don't know very much about abiogenesis but cramming it into an earth-sized time frame strikes me as myopic, considering how much of what life needs comes from space, off planet as it were.
    Where the telescope ends, the microscope begins. Which of the two has the greater view?

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    Here are a few things I've read recently which seem relevant here:

    Physical foundations of biological complexity

    How Phosphorus Came In From The Cold

    Chiral Molecules May Have Hitched Meteor Rides To Planets

    Over and again, the things needed for lawki are extraterrestrial in nature. Considered with the genetic evidence in the OP, we're left with a very brief period of time for abiogenesis-on-earth hypotheses to explain themselves. And if it shown that this happens rapidly in the right conditions, well cool! Could we then assume life of some sort should be everywhere?
    Where the telescope ends, the microscope begins. Which of the two has the greater view?

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    Quote Originally Posted by A.DIM View Post
    Yes, we don't know very much about abiogenesis but cramming it into an earth-sized time frame strikes me as myopic, considering how much of what life needs comes from space, off planet as it were.
    And on, as well. It fell to Earth, with its big liquid water oceans and mineral-spewing hot smokers. A natural place to brew witches.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    I'm skeptical about such attempts to find the date of LUCA, the Last Universal Common Ancestor. It uses the molecular-clock technique (Molecular clock - Wikipedia), and that is not very reliable. For instance, estimated dates for the divergence of the animal phyla have jumped around quite a bit. The authors of that recent paper may nevertheless have been very careful about it.

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    Quote Originally Posted by lpetrich View Post
    I'm skeptical about such attempts to find the date of LUCA, the Last Universal Common Ancestor. It uses the molecular-clock technique (Molecular clock - Wikipedia), and that is not very reliable. For instance, estimated dates for the divergence of the animal phyla have jumped around quite a bit. The authors of that recent paper may nevertheless have been very careful about it.
    I expect they were peer-reviewed, but I agree, these "clocks" are uncertain.

    "When using either a strict- or relaxed-clock method of genetic analysis, the most important consideration is how to calibrate the molecular clock.
    ...
    Thus, to calibrate the molecular clock, one must know the absolute age of some evolutionary divergence event, such as the split between mammals and birds. An estimate of the timing of this event can be gained by examining the fossil record, or by correlating this particular instance of evolutionary divergence with some geological event of known antiquity (such as the formation of a mountain range that split the geographic range of a species in two, thus initiating a process of speciation). Once the evolutionary rate is calculated using a calibration, this calibration can then be applied to other organisms to estimate the timing of evolutionary events."


    If calculating LUCA this way is unreliable, it suggests our knowledge of rocks and fossils, and their ages, is inaccurate and incomplete. And rightly so... again, Horizontal Gene Transfer is hardly considered in these calibrations.
    Where the telescope ends, the microscope begins. Which of the two has the greater view?

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    Quote Originally Posted by A.DIM View Post
    If calculating LUCA this way is unreliable, it suggests our knowledge of rocks and fossils, and their ages, is inaccurate and incomplete. And rightly so... again, Horizontal Gene Transfer is hardly considered in these calibrations.
    I might not understand you correctly here, but I don't see the connection. Rocks and fossils are dated by a variety of methods, whenever possible by more than one method, that are completely independent from "molecular clock" dating. Molecular clock dating is rather recent compared to many other methods and is not commonly (ever?) used for dating rocks and fossils. It is commonly used to date "events" in the evolutionary history of organisms that are evident in a genome. For example, it has been used to attempt to date population bottlenecks that are evident in various species genomes such as humans'.

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    Also, MC might just as easily be wrong in the other direction: more recent instead of older.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by A.DIM View Post
    If calculating LUCA this way is unreliable, it suggests our knowledge of rocks and fossils, and their ages, is inaccurate and incomplete. And rightly so... again, Horizontal Gene Transfer is hardly considered in these calibrations.
    Or else they are careful to watch out for that also.

    But a serious problem is what fossil calibration points are available for early life.

    From Beyond fossil calibrations: realities of molecular clock practices in evolutionary biology, about half of all molecular-clock papers have been on vertebrates, and most of the rest on invertebrates and plants. Vertebrates and some invertebrates, like arthropods, have hard parts that reveal much about their anatomy, so their fossils can be very useful.

    The timing of eukaryotic evolution: Does a relaxed molecular clock reconcile proteins and fossils? | PNAS -- allowing rates of molecular evolution to vary in different lineages. It used 129 proteins from 36 organisms, using these calibration points:
    • Eudicot - monocot split of flowering plants in the Jurassic (144–206 Mya)
    • Moss - vascular-plant split of land plants in the Ordovician (443–490 Mya)
    • Ascomycete fungi (yeasts, molds, ...) originating before the Devonian (417 Mya)
    • Ray-finned and lobe-finned fish split in the Devonian (354–417 Mya) (land vertebrates are descended from lobe-finned fish)
    • Diptera (flies, mosquitoes) - Hymenoptera (wasps, bees, ants) and Lepidoptera (moths, butterflies) split in the Devonian - Carboniferous (290–417 Mya)
    • Chelicerata (spiders, scorpions, mites, horseshoe crabs) - Pancrustacea (crustaceans, insects) split in the Cambrian (490–543 Mya)

    Not very precise dates.

    It finds that the bilaterian animals split up into protostomes (arthropods, annelids, mollusks, ...) and deuterostomes (echinoderms, vertebrates, ...) at about 642–761 Mya (mean 695 Mya), about 200 million years before the base of the Cambrian. Some previous estimates are even older.

    It also estimates the root at the eukaryote tree at about 950-1,259 Mya (mean 1,085 Mya), and green algae / land plants - red algae parted ways at about 925–1,061 Mya (mean 928 Mya). That latter date conflicts with the date of the oldest known red alga, about 1,200 Mya (Bangiomorpha pubescens).

    Other early-eukaryote dates are for early animals at Doushantuo (600 Mya), green algae and testate (shelled) amoebas (750 Mya), stramenopiles (diatoms, kelp, etc.) (1,000 Mya), red algae (1,200 Mya), one-celled eukaryotes or eukaryote spores (1,500 Mya and possibly earlier), and biomarker evidence (2,700 Mya).

    So that study in PNAS gave a rather sensible result for the earliest bilaterian animals, but it underestimated the age of the earliest eukaryotes, likely 1.5 to 2 billion years ago. But that early divergence was well before the divergences used for calibration, divergence which were mostly Paleozoic with one Mesozoic one.
    Last edited by lpetrich; 2018-Sep-17 at 02:35 PM.

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    A genomic timescale of prokaryote evolution: insights into the origin of methanogenesis, phototrophy, and the colonization of land | BMC Evolutionary Biology | Full Text -- used these calibration points:
    • Eukarya -- red algae (1.2 Gya -- billion years ago)
    • Eubacteria - cyanobacteria - Great Oxygenation Event (2.3 Gya)
    • Biomarker evidence of eukaryotes (steranes) and cyanobacteria (2a-methylhopanes) (2.7 Gya)

    Not much to work from.

    Reappraisal of hydrocarbon biomarkers in Archean rocks | PNAS (2015) -- claims that the purported 2.7-Gya biomarker evidence is contamination.
    The advent of oxygenic photosynthesis set the stage for the evolution of complex life on an oxygenated planet, but it is unknown when this transformative biochemistry emerged. The existing hydrocarbon biomarker record requires that oxygenic photosynthesis and eukaryotes emerged more than 300 million years before the Great Oxidation Event [∼2.4 billion years ago (Ga)]. We report that hopane and sterane concentrations measured in new ultraclean Archean drill cores from Australia are comparable to blank concentrations, yet their concentrations in the exteriors of conventionally collected cores of stratigraphic equivalence exceed blank concentrations by more than an order of magnitude due to surficial contamination. Consequently, previous hydrocarbon biomarker reports no longer provide valid evidence for the advent of oxygenic photosynthesis and eukaryotes by ∼2.7 Ga.
    Some of this work is also described in Deep time biomarkers: a study of organic matter and fluid inclusions in Precambrian rocks | Macquarie University ResearchOnline.

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    There are other sorts of evidence that one can look at, like variations in isotope fractions. Not as good as detecting complicated molecules like steranes or hopanes, but it is better than nothing.

    Evidence from fluid inclusions for microbial methanogenesis in the early Archaean era | Nature
    Lower C-13 concentrations in fluid includes in 3.5-Gya rocks from the Pilbara craton in Australia. Evidence of methanogens from back then.

    Physiological and isotopic characteristics of nitrogen fixation by hyperthermophilic methanogens: Key insights into nitrogen anabolism of the microbial communities in Archean hydrothermal systems - ScienceDirect
    Some methanogens can fix nitrogen, with that nitrogen being depleted enough in N-15 to recognize in 3.5-Gya hydrothermal deposits.

    Methanogen energy-source metabolism: CO2 + 4H2 -> CH4 + 2H2O
    Nitrogen fixing: N2 + 3H2 -> 2NH3

    Only about a billion years after the origin of the Earth, about 4.55 Gya. The Late Heavy Bombardment happened about 4.1 - 3.8 Gya, not long before.

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    I decided to explore the methanogens further, to see how far back that ability goes in the tree of life. Higher-level classification of the Archaea: evolution of methanogenesis and methanogens
    Methanogenesis requires a sizable number of proteins, and at least in some cases, these proteins' genes are scattered over the genome. This makes it difficult to do lateral/horizontal gene transfer with them, and the authors conclude that the methanogenesis mechanism originated only once and was vertically inherited.

    Methanogens diverged very early into two groups of them, and mixed in among them are some non-methanogenic organisms (Halobacteriales, Thermoplasmatales and Archaeoglobales). Given their position in the family tree, they likely lost methanogenesis. Halobacteriales was named after the extreme salt tolerance of that taxon's members. Most members of the other two groups tolerate very hot conditions and some of them also tolerate very acid conditions, like in some hot springs and hydrothermal vents.

    In fact, methanogens and their non-methanogenic descendants cover the taxon Euryarchaeota (Euryarchaeota - Wikispecies).

    Euryarchaeota is an early branch of Archaea, alongside DPANN and TACK. Archaea, in turn, is one of the two branches of prokaryotes, branches which stem from the Last Universal Common Ancestor (LUCA) of all cellular organisms with known biochemistry.

    Physiology, phylogeny, and LUCA
    The physiology and habitat of the last universal common ancestor. - PubMed - NCBI
    Methanogens are much like the LUCA, though the LUCA used somewhat different chemical reactions to get its energy. Methanogens make all their biomolecules from simple precursors, much as plants do, and they do not use molecular oxygen or release it.

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