So a couple of days ago it was announced that new fossils of microorganisms were possibly discovered around former hydrothermal vents. According to the paper these fossils "are at least 3,770 million and possibly 4,280 million years old" making them the earliest instance of life found so far. If the upper estimate is correct that would mean these organisms existed "only" ~250 million years after the formation of Earth.

Does this discovery shake up any of our previous ideas and/or provide new insights about the earliest life?

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    $\begingroup$ One can make a comparison between dating of extremely old fossils but IMO, no one can really answer to the question there new insights to be gained? as this very much depend on your specific interest. In other word, IMO, this part of the question is to broad. $\endgroup$ – Remi.b Mar 3 '17 at 20:35
  • $\begingroup$ I don't have access to Dodd et al. 2017 that you cite but I suspect they made comparisons with other recent discoveries. As you cite the abstract, you might have not read the paper. You should probably just try to read it. $\endgroup$ – Remi.b Mar 3 '17 at 20:37
  • $\begingroup$ @Remi.b I don't have access to the paper either :). I mean insights about earliest life/abiogenesis but yes I'll edit the sentence. I'm not so much looking for a copying of the article's discussion but more the scientific consensus on the importance of this find but I'm not sure if that exists yet. $\endgroup$ – Koen vd H Mar 4 '17 at 9:49

Not a lot, the sample is not conclusively biotic in origin nor is it necessarily much older than known fossils, 3.7 billion vs 3.5 billion. The sample is a few simple hematite filaments, complex hematite filaments do form as a byproduct of oxygen using (aerobic) bacteria, they can also be formed by metamorphic processes. Subscribing these filaments to life and proposing oxygen must have been present far earlier than any evidence supports based on this is wishful thinking at best.

If it were correctly identified and as old as possible it would have only a small effect, it would make finding life on other planets more likely becasue it would mean life forms basically as soon as you have persistent liquid water. It might indicate oxygen earlier than suspected but that seems unlikely.

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    $\begingroup$ As I have not read the paper, could you please develop on the sample is not conclusively biotic to include a discussion of their sampling technic? Also, when you say is it necessarily much older than known fossils can you please provide referenced examples to allow a reader to make a comparison? $\endgroup$ – Remi.b Mar 3 '17 at 20:33
  • $\begingroup$ The OP's own linked articles discuss it. But I will expand. $\endgroup$ – John Mar 3 '17 at 20:57
  • $\begingroup$ Nice answer. However, could you add a reference on the different ways these filaments can be formed? $\endgroup$ – fileunderwater Mar 4 '17 at 13:40

The effect of this hypothetical discovery (because I haven't seen the dating of the rocks yet) is almost non-existent. It just reinforces an idea already present in the origins of Life community for a lot of time-you discover life as soon as you discover solid rocks capable of creating fossils, so Life must have originated immediately after the cooling of the Earth's surface or possibly it simply originated elsewhere in the Solar system and was transported here by meteorites (there is solid evidence for this hypothesis in the ability of bacteria to survive extreme environments). What is important however is the reinforcing of the idea there is some "missing link" in the history of the transition of chemistry to biology which is definitely not in the fossil record!

The fact we can't discover some intermediary complex molecules between the primeval Earth and the bacteria means for most of the scientists that either Life simply "hitched a ride" on some comet or meteorite to come here from some other place in the Solar system it originated (possibly Mars) which in turn would imply that the entire Solar system gave rise to a single "type" of Life and therefore even if we find Life outside Earth it will probably be based on DNA and the central dogma and be too much like our own or that the emergence of Life was so fast it simply can not be by chance! I think the implications of the second case are greater but the first one can make a lot of "noise", too I guess (especially if they find bacteria on Mars and they turn out to be just like those here). I myself, however, am a little bit of an "heretic" here and believe the continuous occurrence of the same fossils everywhere in the ancient geological record (and in meteorites from Mars, too) may indicate a little bit different view of what Life can be defined as. What we are looking here are not evidence of cells, but rather evidence of metabolic products which we (not they by themselves) contribute to cells! Because modern cells can produce such products we assume they are produced by cells! But we don't have cells we can look at under the microscope in those rocks. We have thin bands of material we think comes from cells (it is the same with the Martian meteorites-science in a way becomes a "point of view" which you should consider isn't very "scientific"). But what if these bands were the result of metabolism, but is was not cellular! I myself think this is entirely possible, but most of my colleagues do not even consider this idea. This can easily explain the rise of products of metabolism early on but at the same time give enough time for the complexity of the modern cells to form under the influence of great competition among metabolic pathways themselves, rather than living cells-for which we seem to have direct evidence at a much later period. This hypothesis can also explain why are all the basic metabolic pathways in Life today so conservative (unlike the genes themselves which determine them-what is really more conservative-the gene or its role?) while the proteins coding for them can be coded under different genomic organization-e.g. different structure of the genome in different domains. The place of the gene can change, even to a certain extent its sequence, but what remains the same is their relationship to each other, e.g. their topology to respect of each other in the general graph of metabolism. Why? What if metabolism was more ancient than cells, but the evidence of this "metabolism evolution" was lost in the age before the cell(because there were no cells, no structures, no anything to leave fossils of the metabolism evolution, excepts its waste products (in a way its "coprolites"). I would like to think this evidence supports such hypothesis but again it is just an opinion.

I hope you like this answer.

  • $\begingroup$ Your answer is rather hard to follow, are you saying metabolism started inorganically? $\endgroup$ – Koen vd H Mar 4 '17 at 19:11
  • $\begingroup$ Not exactly, actually I am saying what we perceive today as metabolism was the way the first form of life evolved in the beginning of its history. Actually, I (and not only me, of course) put forward the idea of gradual metabolic evolution whose waste products formed what we today find as the oldest fossils of living organisms. I think we don't have enough data to call them results of cellular activity, so they could well be the results of metabolic activity before the rise of cells. If metabolism evolved first, then its fossils can exist even if there weren't cells during that time. $\endgroup$ – Yordan Yordanov Mar 4 '17 at 21:27

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