There is no evidence yet of life outside the earth. There is only evidence for the possibility of life in the form of bodies in the Solar System that have water and other features expected to be key to life anywhere. Yet, some of the sites outside the earth are not substantially different from extreme microbial environments on earth where life was believed impossible until discovered just 40 years ago in the hot springs of Yellowstone National Park. So the most probable forms of life elsewhere in the solar system would resemble microbial extremophiles based upon what we know of possible sites. The existence of life in these sites on earth and its only recent discovery provides reasonable grounds to assume life could exist in these places outside the earth. Given that it took us so long to discover life in hot springs that were readily accessible to investigation, we might wish to allow a bit more time to investigate places outside the earth before assuming they will have no life.

John, I share your optimism. However, I guess Elena's question dealt with the possible existence--current or past--elsewhere in the Solar System of chemical and physical conditions that were potentially life-forming. No matter how extreme the Yellowstone conditions are now, it is unimaginable that the chemical and physical conditions that we know of Venus would support life-forming processes, so is Mercury. The rest of the places are all cold (Mars) or ultra-cold. We do see life forms surviving in very cold conditions on Earth, but that does not mean that those life forms originated in such cold conditions. The presumptive conditions on Earth that saw life's emergence was not cold--as far as I have read. And, we have no evidence of any past hot conditions on the surfaces of the cold planets or their moons. Recent claims that cold meteor-collisions led to formation of aminoacids and related ingredients of life are as yet lame, for mere formation of a handful of ingredients does not constitute emergence of life. Mars likely had a warmer past, but with the acidic, oxygen-deprived and high-saline Martian conditions, do we hope that life ever evolved there just because of a warmer temperature? I do not. Besides, the much-hyped methane excitement is dead now.

Now, coming to Elena's question directly, how do we know if ever a potentially life-supporting condition existed on other parts of the Solar System? This is my personal view that whatever we "know" of our Earth's past owes a great deal to human imagination and speculation. For, we cannot understand what Earth was a million or 4 billion years ago. We were not there to record the conditions. All we know is based on philosophising some experimental observation, and that is heavily dependent on speculation.

While I fully share Elena's question and do wonder countless times about life forms elsewhere, I think there is currently no real ground to assume that life-supporting conditions existed elsewhere in Solar System. That said, I do think that we are not alone, and the Milky Way--let alone the rest of the space--has active life forms. But to know of them will be close to impossibility, for we have developed no such technology thus far. There are our fellow living beings in our galaxy, but we are too far apart to have an inkling of each other. This is why I believe the entire SETI project was too premature and a total wastage of money, time, efforts, thinking, patience and emotions. Maybe it will be worth visiting the SETI ideas in 3013.

Elena and John, here is a disclaimer. I must state here that I have had no theoretical or experimental training/research in this field to make an opinion like what I wrote above. I believe that such scientific discourses should be based on authoritative expertise and not on merely speculative, layman-like statements.

However, I wrote the above with a little bit of assumption that I understood a little bit of this subject. I am still an illeterate layman in this very context; but I felt that sometimes well-publishing experts may also have much poorer scientific judgment than a layman. Take a recent paper in the respectable "Astrophysical Journal". The guidelines for defining "habitable zone" of a star being two decades old, the authors set out to redefine the guideline (see http://arxiv.org/pdf/1301.6674v2.pdf). Experts in the field lauded the article and the new model (see http://www.sciencedaily.com/releases/2013/01/130130132413.htm). So far so good; but I find that when the model was tested on Earth, it placed Earth on the periphery of Sun's habitable zone, implying that the Earth is "barely habitable". We know that Earth is not only the only planet to have supported life, it does so overwhelmingly magnificently. Therefore, any model defining the habitable zone of a star must predict the Earth within the thick of the habitable zone. That is the only positive control that we have, and if that is not true, the model is as good as trash. I raised this question, that why the model showed Earth as barely habitable, with the lead author, who chose not to respond.

I understand the situation well: it is easy to raise pertinent questions and to address them when the material and resources are directly available (like, asking and addressing questions on gene regulatory mechanisms and their implications in cancer), but it very difficult to stay away from errors and speculations when we are trying to address questions beyond our physical reach.

I would request Elena, as the initiator of this question, to please put forth her opinion about the question she raised, the possible means to address those questions, the possible results and interpretations, and the feasibility of moving forward in this research. This is a very interesting question, and we must start serious efforts to address this one. As it made news this week, the Earth is expected to support life for another 1.75 billion years; but well before that humanity must find alternative worlds to relocate. And, with Voyager 1 taking 36 years to exit the Solar System, we have not yet started taking the baby steps.

What would be convincing evidence to you that earth-like life could existing under conditions known on other planets?

I do not think earth-like life would be existing under conditions known on other planets--unless those conditions are similar to Earth's. And we have not found any such planet yet. Starting with the origin and molecular evolution of the primitive genetic material upto the current time, the life on Earth has tried, retained and discarded numerous forms. Under similar conditions elsewhere, I expect at least the similar life-forming/supportive mechanism (ingestion and assimilation of nutrient, excretion, reproduction) and architecture (evolvable morphology as means of adaptation) to exist. But I am at the moment cluless about what I would consider as the evidence of life elsewhere.

Anil,

I like your interventions which seem quite relevant to me.

Actually the notion of an "habitable zone" of a star is not trivial: why?

Because the concept of 'life' is questionable (see my paper on RG: "Is A n+1 Definition of Life Useful?").

It seems to me that an universal definition of 'life' will never appear because the concept of 'life' is a metaphysical concept and not a scientific one.

Then, is it nevertheless possible to specify an "habitable zone" of a star?

I think it is possible if the researchers give up the concept of 'life' and instead focus on how Darwinian evolution could have emerged on early Earth (see my paper on RG: "Origin of Evolution versus Origin of Life: A Shift of Paradigm").

If so, depending of your hypothesis, it is possible to define a range of conditions.

For instance, according to the hypothesis I propose (i.e., on how Darwinian evolution had emerged on early Earth): "Celestial bodies considered as candidates for the emergence of evolution should plausibly have a very long-standing process of plate tectonics in order to allow the occurrence and maintenance of deep-sea hydrothermal sites such as Lost City Hydrothermal Fields. These constraints would add to classical requirements, e.g., basic ingredients such as reduced carbon-based molecules and liquid water".

Dear Kenneth, thank you. I felt the model was same as designing an instrument, to detect trace amount of proteins, which basically sees barely any difference between plain water and an aqueous protein solution at 10mg/ml.

Anyway, the new reports in Science today, that the Martian soil has abundance of water molecules trapped within, will certainly interest you, Marc, Elena and John. . I have not read these fully (not that I will understand them well, being a basal-level molecular biologist), but these new reports would certainly add fuel to this thread. Elena, since these reports perhaps seem closer to your question, would you kindly share your opinion with us? We could move forward from there.

Kenneth,

I agree with you that Ravi Kopparapu et al's paper is very much prudent in its assertions.

As mentioned by the authors the first idea of such calculations comes from Kasting et al. (1993) with his cloud-free climate model.

In Kasting's and Kopparapu et al's models the Habitable Zone (HZ) is defined as "the circumstellar region in which a terrestrial-mass planet with a CO2-H2O-N2 atmosphere can sustain liquid water on its surface".

This is the main issue of these models: how do they justify such an hypothesis? In other words, which definition of 'life' do they take into account for justifying it?

This is not really and clearly argumented by the authors. Actually it cannot be because, as I already claimed it, an universal definition of 'life' is impossible because the concept of 'life' is not a scientific concept but instead it is a metaphysical concept.

Kenneth,

You didn't reply to my argumentation about the issue with any definition of 'life'.

Your assertions and my comments:

1) the planet has liquid water:

Why not, but how do you argue it more specifically?

2) the planet has no potential for UV damage to proteins or to DNA….in its 'habitable zone':

Clearly your definition of 'life' implies the existence of proteins and above all of DNA. Thus, you go further than the supporters of the RNA world hypothesis!

3) any early "life" i.e. lower forms of life, are or can be a source of free molecular oxygen…Photosystem II photosynthesis, or equivalent:

So you consider that 'life' cannot emerge without using photosynthesis. Moreover you support the idea that early 'life' must be a source of molecular oxygene (!).

4) For higher forms of life, evolution of collagen or a substitute structural protein:

This condition is off topic for the emergence of the first "living matter".

5) A net source of free molecular oxygen…critical to higher forms of life (Metaphyta or Metazoa) All higher forms of life on Earth… animals… require collagen, which mandatorily requires molecular oxygen:

This is still off topic.

Dear All,

Thank you for your discussion and, I hope, for its continuation. I enjoy when reading the majority of your opinions, which hides, at times, the deepness of the thinking behind the seeming lack of seriousness. It is my honor and pleasure to take up your call and express some opinions in line with some of your interesting ideas. As for my relation to the question under consideration, in 2007, we wrote that nowhere over the Solar System but Mars life is possible. Just DNA formation is a necessary condition and the possibility for life origination. It is necessary to reveal three minerals that, meeting together, could produce DNA; just three, because the meeting of four appropriate minerals is extremely unlikely. It is surprising, but only one triad of such minerals is possible: CH4 (or other CH4-hydrocarbon) and NO3- and PO4-ions. No other three minerals can provide the necessary redox reactions. The second condition is the occurrence of an appropriate mineral matrix, which limits the growth of the DNA components and provides the DNA monochirality. Only one such a matrix is presented by nature: the so-called methane-hydrate, which is a solid mineral that exists at about 273 K under a methane pressure under ground or seabed. And no oxygen is required! Moreover, O2 (and N2) evolves in the course of the reactions. Only Mars of all the Solar System celestial objects may contain methane hydrate in its crust formed from CO2 and hydrogen in the past (CH4-hydrate may exist deep in the soil). The presence of small amounts of nitrogen and oxygen in the atmosphere of this planet is probably due to reactions similar to the above-described ones. We wrote in 2007 that «…however, Mars appears to have always been cooler than Earth; therefore, if such a reaction had indeed occurred in its crust, the subsequent process of complicated chemical transformations from their products to the emergence of the first cellular organisms would have lasted much longer than on Earth, and, hence, the probability of its interruption at an intermediate stage was significantly higher. In our opinion, any primitive life that may possibly exist on Mars should not be regarded as traces of a highly organized past life; it simply did not reach the level of life that thrives on Earth.» (Ostrovskii, V.E., Kadyshevich, E.A., Generalized hypothesis of the origin of the living-matter simplest elements, transformation of the Archean atmosphere, and the formation of methane-hydrate deposits, Physics-Uspekhi (Adv. Phys. Sci.), 50 (2007) 175-196). These ideas were developed by us and led to a physicochemical explanation of the intracellular processes and new approaches to the problems of optimal nutrition and life prolongation (the last review paper is published in Ostrovskii, V.E., Kadyshevich E.A., Life Origination Hydrate Hypothesis (LOH-Hypothesis): Original approach to solution of the problem, Global J. Sci. Frontier Res. (A), Phys. & Space Sci., 12 (6) (2012) 1-36 (both papers are available at ResearchGate). I hope that I answered most of your questions, and I would be very grateful to you for continuation of our discussion.

Thank you again,

Regards, Elena.

Dear Elena,

Thank you for your long clarification on your ideas about life origination. I know that Victor Ostrovskii and you are often co-authors in papers on the matter. I have already had the opportunity to exchange with Victor on his recent publications on life origination.

By the way I must admit I don't share your common assertion at all that "just DNA formation is a necessary condition and the possibility for life origination".

How do you argue it?

Elena, Thanks for elaborating your thoughts behind your question. I agree that the co-occurrence of those three minerals would be the necessary precondition to DNA/RNA synthesis and evolution. However, the mere occurrence of these three minerals will do nothing; it has to be supported by other factors in the environment. You took the effect of the existing temperature into conderation; but what about other factors on Mars, like high salinity and high acidity? Besides, it is conceivable that these three minerals could lead to the formation of nucleotides; but how do we expect the nucleotides to plymerise under such primitive conditions? That too, without shielding the UV assault? How less would be the penetrance/magnitude of the solar UV radiation on Mars, compared to Earth's pre-ozone era? I have got this notion that the UV-shielding protection was provided by sea water on Earth, and gradual bloom of cyanobacteria led to ozone accumulation (this is from readings over 20 years ago, and I may be wrong) and subsequent boom in life form diversity and number; but can we think that Mars ever had the ability to provide such aquatic abundance necessary for emergence of early life-forming components?

Kenneth,

Within my hypothesis that Darwinian evolution has emerged within deep-sea hydrothermal sources (such as the Lost City Hydrothermal Fields) it is clear that the first systems able to show Darwinian evolution were protected from UV radiations (Tessera, 2011).

Marc, the Lost City vents are highly alkaline today. Have they been so through out their history? Are all similar vents (not the black smoker ones) supposed to be so highly alkaline? If so, how does this high alkalinity fit with your hypothesis? Are the chemical reactions generating life-forming components (nucleotides, saccharides, amino acids) from the PCN precursors (short for Elena's CH4-hydrocarbon, NO3- and PO4-ions) possible in extreme pHs--that is, very high in the Lost City vents and very low on supposed Martian oceans in past? Or, does your hypothesis assumes that the life-forming reactions took place in the peripheral zones with milder conditions?

Besides, I have a critical (and, you may dislike this, philosophical) question here. How does hypothesizing help in such matters where experimental verification is not possible? Are we eternally condemned to hypotheses, never to be able to know what actually happened? If we are not sure of what happened on Earth (where we live, whose history we have dug out in great details, which we "know" pretty well, etc.), how on earth we are going to "know" what happened (or, not) on Mars or elsewhere?

The extreme of this seemingly "directionless" direction is the Big Bang, that "all matter and energy of the universe was once condensed into an infinitesimally tiny dot, to which no material (physical/chemical) law, principle or logic could be applied". Principly, physics is one discipline that always shunned guess-work and, instead, always relied on experimental verification. Then, why do the physicists talk something so illogical (that is, "something could exist where no logic exists")?

I feel like we are similar to those four partly-immobile blind fellows who described an elephant by simply touching it. One held that the elephant is a not-so-thick but very-wide fan-like flap, the other felt it as a strong cylindrical trunk, another felt it similar to a snake with a tuft at the end, and the other felt like the animal was similar to a cylindrical sword.

At least the blind people were correct within their own right (and within their purview of observation). Can we claim that we are similarly right?

I guess there was certainly a shift in the life of the primitive organisms towards photosynthesis; for, the earliest known fossil evidence of life forms comprises of the stromatolites that were formed by photosynthesizing cyanobacteria. But that happened only after a protracted, UV-bombarded journey full of struggles and deprivation. I would spend some spare time looking into past and current research on how small monomeric chemical entities are perceived to have transformed into entities that grow, ingest and reproduce. Jack Szostak (http://molbio.mgh.harvard.edu/szostakweb/publications.html) claims to have developed lipid protocells that grow and divide (a team of Harvard relevant to this discussion can be browsed here: http://origins.harvard.edu/people/research-faculty; but I believe there are other teams elsewhere that are also doing quality research on this front). But I would seek the explanation for this phrase: "the whole is greater than the sum of its parts". I know Marc does not like this question; but can humanity shy away from this question?

Anil,

I am not sure to quite understant the meaning of your speech.

By the way, did you read my 2011 paper as many of your questions are answered in it?

I don't understand your questioning "How does hypothesizing help in such matters where experimental verification is not possible?" as the hypothesis of the emergence of Darwinian evolution wtihin alcalin Lost City-like hydrothermal sources is perfectly testable and a lot of experiments have already been carried out.

Sorry, but you should learn more about the field before asserting strong conclusions.

Kenneth,

I agree that, to evolve further the organisms would have needed to move to additional local and especially additional sources of energy (e.g., "on Earth, PS-I and PS-II were the evolutionary choices… and into shallow waters, into the photic zone").

Actually this is not at all the problem of the emergence of Darwinian evolution, rather the problem of how the story has continued after this primordial event.

Kenneth,

I am sure you didn't read my 2011 paper.

The dilemma of the required loss of water in the oceans implied by the synthesis of polypeptides indeed would have existed if the reactions occurred freely in the water. The issue is totally different if these occurred inside lipid vesicles, particularly if , in addition, they were catalyzed by the vesicle membrane (as proposed in the model shown in my 2011 paper).

Kennetth,

Thank you for your Science Letter published in 1991. A the time you wrote it your comments were surely interesting. However today these are somewhat outdated.

Since 1991 there has been for instance the discovery of new hydrothermal sources like the serpentinite-hosted Lost City Hydrothermal Fields (LCHF).

LCHF is an extreme endmember in which hydrothermal geochemistry is controlled primarily by serpentinization reactions that produce pH 9–11, temperature ≈ 40–91°C fluids enriched in H2. In addition, these fluids are enriched in calcium. Hence, mixing of these fluids with seawater results in the precipitation of large carbonate chimneys. Actively venting chimneys and flanges are highly porous as they show fine anastomosing networks of carbonate lined with brucite, with tiny interconnected pores on the micrometer scale, indicating the mixing of seawater and hydrothermal fluids within the interior walls. Fluids percolate through the carbonate anastomosing networks. Thus theses very specific local conditions are quite favorable to biochemistry as thermodynamic calculations demonstrate that biomass synthesis is most favorable at moderate temperatures such as at LCHF, where the energy contribution from HCO3 and H+ in seawater coupled to the reducing power in hydrothermal fluid are optimized. Moreover experiments simulating molecular transport in elongated hydrothermal pore systems showed extreme accumulation of molecules in a wide variety of plugged pores. Other experiments demonstrated that thermal gradients across narrow channels can provide the energy necessary to concentrate dilute molecular solutions and thus allow the self-assembly of lipidic vesicles from an initially dilute solution. Vesicles with membranes composed of bi-layers from mixtures of amphiphilic and hydrophobic molecules could have formed from the organic compounds present locally at high concentrations. The stability of bilayer lipidic membranes at high pressure and temperature is nevertheless still debated. Experiments have shown that bilayers formed of simple amphiphiles are extremely fragile: high pH, ionic strength, high temperatures (even 45°C) will destroy them. However primitive membranes would have been composed of a diverse mixture of amphiphiles. This mixt character may have imparted essential stability to primitive membranes.

Dear Marc,

My speech was inspired by your posts. Recall that you wrote "'Within my hypothesis' that Darwinian evolution has emerged within deep-sea hydrothermal sources (such as the Lost City Hydrothermal Fields) it is clear that the first systems able to show Darwinian evolution were protected from UV radiations (Tessera, 2011).". Please note that you did NOT write "I have experimentally demonstrated that...'; instead, you wrote "within my hypothesis that...". That clearly shows that the Darwinian evolution and the UV protection that you are talking about happened in your hypothesis only, and you have not demonstrated it experimentally. And I know that it is impossible to demonstrate evolution experimentally (see below).

This discussion shows clear disagreements (as well as agreements) among the participants--see the postings above. That is natural and expected. Because, each of us differs in the amount of knowledge and understanding we have gathered, and thus our logic differs; so do our hypotheses. Such ambiguity can be removed when we prove our hypotheses correct, by conducting adequate logical experiments and careful interpretations. Do not get me wong please, I am NOT a creationist; but human intelligence cannot demonstrate evolution as seen on Earth [although we can potentially make a better enzyme by random mutagenesis, mutagenesis in vitro is NOT evolution]. We observed gradual changes from early primates to apes to humans in the genetic, morphological, anatomical, behavioral contexts; these observations are consistent with our notion of evolution, but are not evidence of man evolving from the apes. There is a huge difference between "suggestive observations" and "evidence". In your article, you have not demonstrated experimental evidences in support of your hypotheses.

My point is, no matter how well constructed your (or Elens's or whoever's) hypothesis is about abiotic origin of life and its evolution, we CANNOT demonstrate the exact route(s) of life's origination and evolution that "actually" took place. All that we can do is raise hypotheses, and try to make some observations within Earth's biogeochemical treasures and join some dots that fit into our hypotheses; we do not quite have the room to conduct experiments on the way Earth did. Earth is temporally and spatially too huge for human intelligence to recapitulate. This is why I asked " How does hypothesizing help in such matters where experimental verification is not possible?"

I have read the articles about computer-simulated maps of the universe at various time points during its evolution post Big Bang. I do not laugh at those articles and their authors and funders; I sometimes feel pity, sometimes hopeless. And I do not think we are anywhere close to those four fictitious blind men.

Kenneth,

I think there is a misunderstanding:

- You seem to be mainly interested in how evolution has followed its path on Earth once 'life' (or preferably 'Darwinian evolution') appeared;

- While I thought the main question of this thread was: is there any probability that 'life' (preferably 'Darwinian evolution') has emerged anywhere, but the Earth, in the Solar System?

Anil,

You are perfectly right when you oppose me that I have not yet demonstrated my main hypothesis (i.e., the possibility of mutual catalysis inside lipid vesicles thanks to its heterogeneous membrane) experimentally.

I have planned experiments but presently I am not in a position to do these experiments myself.

However you seem to support the idea that it is impossible to carry out any kind of experiments to demonstrate the proof-of-concept (at least) of any hypothesis as you write:

"My point is, no matter how well constructed your (or Elens's or whoever's) hypothesis is about abiotic origin of life and its evolution, we CANNOT demonstrate the exact route(s) of life's origination and evolution that "actually" took place. All that we can do is raise hypotheses, and try to make some observations within Earth's biogeochemical treasures and join some dots that fit into our hypotheses; we do not quite have the room to conduct experiments on the way Earth did. Earth is temporally and spatially too huge for human intelligence to recapitulate. This is why I asked "How does hypothesizing help in such matters where experimental verification is not possible?".

Yes, Marc, that is what I am saying. If I hypothesize that "a knife can be used to cut a piece of wood", it is experimentally verifiable. However, if I hypothesize that "under the primitive Earth conditions simpler inorganic molecules transformed into simple organic molecules, which further coalsced into coacervates, which followed Darwinian evolution to finally end up as today's world", then it is not possible to verify or prove it experimentally. Because, the first requisite would be recreation of the "primitive Earth conditions", which is impossible, and then the next is to observe for the entire course of Earth's evolution and record all happenings to be analyzed later, which are not possible.

Now, what do we do, then? The way forward is to "do the next best thing possible". That is, to hypothesize how life emerged and evolved on Earth, and try to mine the richness of Earth's biogeochemical treasures to find some dots that fit our hypothesis. That is what you, I or anyone else is doing. There is nothing wrong in doing so, since we are doing "the next best thing possible". The problem is, owing to the differences in our over-all knowledge, understanding, thinking and expertise, we all differ in the notion of "the next best thing". That is where discripancies result, and there is no way to eradicate that discripancy completely.

If you take the Miller experiment, you will agree that Earth did not use the same proportions of ammonia, methane etc., and did not zap the mixture with electricity. Miller did the "next best thing to do"; as is doing Szostack, or did Oparin, or you are planning or whoever is doing whatever.

The bottom line is, we all are doing a commendable job of pursuing "the next best thing" within our own capacity; but we must accept that it is impossible to do "the best" (refer to the text above). Depending on the compatibility of our thought processes, knowledge and understanding, we shall agree at times and shall disagree at other. That is the best and farthest that we can go.

Anil,

Of course I fully disagree with your very pessimistic view of the problem. I think you are superficially familiar with the domain and thus underestimate our scientific capability to deal with the issue.

However it is true that our knowledge of the exact environment that prevailed on early Earth is still incomplete. In spite of this present state of the art there are nevertheless good arguments supporting the idea that many hydrothermal vents already existed on early Earth, some of which were deep-sea such as the present serpentinite-hosted Lost City Hydrothermal Field. Within the hypothesis that Darwinian evolution has emerged in such deep-sea Lost City-like hydrothermal vents it is not necessary to know exactly the composition of the atmosphere of early Earth. The local conditions within and near these hydrothermal vents should have been rather standardised. The crucial ingredients which were surely present at that time and within theses sites were liquid water, hydrogen, carbon dioxide gas, methane and calcium. These ingredients were sufficient to allow the formation of actively venting carbonate chimneys and the production of amphiphilic compounds composed of aliphatic hydrocarbons (C9-C14), aromatic compounds (C6-C16) and carboxylic acids (C8-C18) which could have led to the formation of lipid vesicles (as proved experimentally).

Dear All!

I should accent that, in my deep convictions, the fulfillment of all requirements to the DNA formation conditions, about which Elena wrote above, are necessary, and the hypotheses that ignore any one of them are not-scientific ones. Below, I list all these requirements again; Elena, may be, did not point some of them, and, therefore, I list the full set of them.

(1) (i) In any one localization, many similar but somewhat different DNAs should be produced or (ii) DNAs should be produced in a very large number of similar but somewhat different localizations; otherwise, the today variety of the flora and fauna could not be provided.

(2) Condition (1) should be realized in different periods and, apparently, at different points.

(3) DNA should be formed as a result of chemical reaction between three mineral substances.

(4) Formation of each of the DNA components and of DNAs as such should be accompanied with an increase in the free energy.

(5) The reactions as a result of which DNAs originated (and those as a result of which DNAs replicate) should proceed under conditions when none of other reactions are possible.

(6) The temperature should be so low that the equilibrium is establishes at each step of the process.

(7) DNAs should be originally formed within a mineral matrix, and, in what follows, the mineral matrix of the same chemical nature should accompany the replication process of all DNAs; therewith, this matrix should arise or dissolve in dependence of the water concentrations in the water/nutrient systems.

Each of these requirements is grounded in our papers, which are available at the ResearchGate, but I am ready to repeat and, may be, to complete any of them or to give the corresponding references, if this is necessary.

As for the UV radiation, in our opinion, if any living matter is on the Mars, it exists under a soil layer, where the solar radiation is not so baneful. However, I think that this is unlikely, because, in particular, I think that the phosphorous content in the Mars soil is much less than in the Earth soil. It follows from our PFO-CFO Hypothesis of Solar System Formation, but this is another song. The occurrence of liquid water is insufficient for living matter origination even if NO3 and PO4 ions are dissolved in it, because the conditions for formation of DNAs are not fulfilled in this case; the solid methane-hydrate structure is sufficient; moreover, water forms as a result of DNA formation by our mechanism.

I am sorry to say, but I think that only the LOH-Hypothesis is today rather deeply developed for its experimental testing. We wrote in our papers that two ways of its testing are possible: the three-dimensional simulation and the international laboratory experiment with autoclaves. At present, when the compatibility of DNA and gas hydrate structures is confirmed (see our publications of 2013 at the ResearchGate) by simulations, the experimental testing is on the agenda.

Best regards.

Thank you for the discussion.

Victor.

Dear All!

I should accent that, in my deep convictions, the fulfillment of all requirements to the DNA formation conditions, about which Elena wrote above, are necessary, and the hypotheses that ignore any one of them are not-scientific ones. Below, I list all these requirements again; Elena, may be, did not point some of them, and, therefore, I list the full set of them.

(1) (i) In any one localization, many similar but somewhat different DNAs should be produced or (ii) DNAs should be produced in a very large number of similar but somewhat different localizations; otherwise, the today variety of the flora and fauna could not be provided.

(2) Condition (1) should be realized in different periods and, apparently, at different points.

(3) DNA should be formed as a result of chemical reaction between three mineral substances.

(4) Formation of each of the DNA components and of DNAs as such should be accompanied with an increase in the free energy.

(5) The reactions as a result of which DNAs originated (and those as a result of which DNAs replicate) should proceed under conditions when none of other reactions are possible.

(6) The temperature should be so low that the equilibrium is establishes at each step of the process.

(7) DNAs should be originally formed within a mineral matrix, and, in what follows, the mineral matrix of the same chemical nature should accompany the replication process of all DNAs; therewith, this matrix should arise or dissolve in dependence of the water concentrations in the water/nutrient systems.

Each of these requirements is grounded in our papers, which are available at the ResearchGate, but I am ready to repeat and, may be, to complete any of them or to give the corresponding references, if this is necessary.

As for the UV radiation, in our opinion, if any living matter is on the Mars, it exists under a soil layer, where the solar radiation is not so baneful. However, I think that this is unlikely, because, in particular, I think that the phosphorous content in the Mars soil is much less than in the Earth soil. It is follows from our PFO-CFO Hypothesis of Solar System Formation, but this is another song. The occurrence of liquid water is insufficient for living matter origination even if NO3 and PO4 ions are dissolved in it because the conditions for formation of DNAs are not fulfilled in this case; the solid methane-hydrate structure is sufficient; moreover, water forms as a result of DNA formation by our mechanism.

I am sorry to say, but I think that only the LOH-Hypothesis is today rather deeply developed for its experimental testing. We wrote in our papers that two ways of its testing are possible: the three-dimensional simulation and the international laboratory experiment with autoclaves. At present, when the compatibility of DNA and gas hydrate structures is confirmed (see our publications of 2013 at the ResearchGate) by simulations, the experimental testing is on the agenda.

Kenneth,

You say: "The question was are there any REAL grounds for assuming the occurrence of LIVING matter in our solar system?".

Ok, but how is it possible to search for such an occurrence if there is no scientific consensus on a definition of a "living" matter?

What I claim is that any definition of 'life' is counter-productive to lead such a search. Instead I propose to search for signs of the emergence of Darwinian evolution.

Hence, within the model I propose for such an emergence, celestial bodies considered as candidates should plausibly have a very long-standing process of plate tectonics in order to allow the occurrence and maintenance of deep-sea hydrothermal sites such as LCHF. These constraints would add to classical requirements,e.g., basic ingredients such as reduced carbon-based molecules and liquid H2O. Does the requirement of the existence of plate tectonics suggest Mars or Europa as possible cradles of evolution?

Another consequence of my model is the suggestion to search for specific signatures represented by the presence of enanthiomers of carbon-based molecules.

Dear Kenneth and Mark,

OK! I will try to comment the issues given by you both.

First, about the Mark's words relative to the term "living matter" definition. I had answered to him earlier that, in my opinion, there is rather wide concensus in this simple question and he muddies the pure waters. I see no grounds to argue against L. Pauling's opinion and my conclusion on this farfetched problem. Just origination of DNAs can be considered as the origination of living matter. I refer again to our with Elena Kadyshevich paper which was published in Russian physical review paper "Physics-Uspekhy" (the title of the English version of the prestige Russian journal). This rather substantial review paper was published in 2007; the terminological question was considered there in details, and the paper is available at the ResearchGate. I think, likely to Pauling, that we have sufficiently many problems and the invention of new non-necessary ones is nonconstructive.

As for the so-called Darwinian evolution, this subject was discussed by us at other ResearchGate pages, the positions are clear, and the diversion to this direction is meaningless. I can repeat that the Darwinian evolution in its Darwin's version does not exist in my opinion and in the opinion of many researches over the world and some proofs were given by me in the context of the ResearchGate discussion.

About the Kenneth remarks... Yes, I think that "if there is any "living matter" on Mars it must have originated and evolved there." It is unlikely that the Mars could be adapted for living of a large popularity. According to our views of the planet-formation process, the Mars is very poor by heavy elements (its mean density is 3.8 only as compared with that of the other terrestrial planets (5.0-5.5)). As for the UV radiation, this is one of additional problems.

Dear Kenneth,

Perhaps, I will add something in answer to your question on the possibility of transportation of living matter from any one celestial object to another one. I think that transportation of cells is impossible because the protoplasm and envelope should be destroyed. As for the DNA, it is rather tolerant and there is some very small probability that such a transfer is possible. However, the DNA as such has no possibility for its replication, and its appearance at any object by no means leads automatically to living matter origination. Viroids represent such an example. They are incapable of replicating out of cells. Thus, the cellular envelope and protoplasm should be formed around the DNA-parachutist. This means that this DNA should get to a medium where protoplasm and envelope can be produced. However, if such a medium and the appropriate conditions for formation of protoplasm and envelope exist in the new house of our DNA, domestic DNAs and cells would form there earlier. Therefore, I think that the idea on the possibility of “precipitation” of life from outside at a lifeless celestial object has no real grounds. This reasoning does not relate to a lived-in celestial object, because our parachutist is capable of searching an appropriate medium for the second life for him and for his posterity. Therefore, there are no grounds to exclude completely the possibility of transportation of some species to the Earth from the space. However, to say deeply about such a possibility, it is necessary to prove many different positions: the possibility of voyages of DNAs with no principal destructions for a long time at about 3 K in the deep vacuum, the occurrence of living matter anywhere “near at hand”, etc. I am nihilist in this question. However, I can’t prove the absurdity of such an intervention of some species of life.

Regards,

Victor

I am interested to know how far the identified environments in the solar system are from those that sustain life on earth. In other words, what modifications would one have to make to get microbes to survive under conditions revealed by space missions and other data on bodies in this solar system. Then creating such experimental conditions would allow one to address questions of tolerance to various stress such as how bad the known UV stress is for existing microbes? Or how far would microbes have to be inside porous rocks and beneath UV absorbing materials. Given that we have no extra-terrestrial life to test, what can we do experimentally with the living systems we do have and how useful might this prove to be?

Kenneth, There now! What did I wrote you? I wrote that I am pissimist. But the faith accepts no negative argumentation. The advocates of the idea of the "transmigration of souls" can say that the cosmic cells can be hidden in the interior of the large meteorites or found any other tale. Of couyrse, science should be grounded on proves and logic but not always it is the case. Therefore, our knowledge of the world develops not progressively but by zig-zags, by trial and error. K. Popper wrote about this.

John and Kenneth, pardon me for the vagueness: I remember an article in Science Daily a few months ago about a study that swiped the outer surface of a high-altitude plane (while flying, I guess), and retrieved the microbes, got them growing in several variations of stringency in growth conditions. Some grew specifically well in the harshest conditions used, but did not do well in the milder conditions. I shall try to find the link and if I get it, I shall post here.

Whether Life on Earth has originated via genetics-first RNA world theory or metabolism-first Fe–S world theory (leaving out all versions of Panspermia), the fact is that Life originated on a planet that had certain requirements which we haven't found (so far) (all requirements that we know), on and in other planets (Solar System planets and Exoplanets).

This may suggest two things (so far).

1) There is the option that our planet is special and so Life is a unique phenomenon. Probably we are desperately alone.

2) Second (I support that), is that the Life is a more common phenomenon than we can speculate scientifically (under our Anthropocentric, Biocentric and Earthcentric view), so the variety of planets and conditions, only reflect the variety of possible types of life and of Abiogenesis zones. Like the variety of habitats here in Earth.

Now well. What are we going to do or how we are going to do, in order to find that Life? To study it, to understand it or simply to perceive it? This Life could be similar to what we know or perhaps, given the variety of planets and conditions, very different. On our planet, it is clear that Life adapts to fit an environment or modifies an environment to be able to survive, in a way that we barely understand.

Here, life could have originated in different zones and in different times, but that isn't the only problem, we don't know how it happened, or when, we only have theories and theories, and theories on theories(Schidlowski, 1988; Hayes, 1996; Feng et al., 1997; Rosing, 1999; Hartmann et al., 2000; Morbidelli, et al. 2001; Hedges et al., 2001; Mojzsis et al., 2001; Nisbet & Sleep, 2001).

All this is ok, we have come a long way since Pasteur, Darwin, Oparin, Watson and Crick, Extremophils, ISS, etc., and with everything we know about life on Earth (albeit little), we have sufficient reason to suppose the occurrence of living matter anywhere of our Solar system and explanets, likely even more in the present than in the past, but the key question (I think) is: How are we going to respond or to prove this assertion, scientific speculation, assumption, etc?

Options:

HABITABLE ZONE. I consider that this concept or theory only has distracted us in our search for life for more than 50 years. HZ is just useful to search for surficial liquid water, but not for Life. If many insist, HZ could be used in the search for “Earth-Like Life powered by stellar photons”. As narrow and Earthcentric as it sounds. Then must be renamed as “Zone for searching for Surficial Earth-Like Life powered by stellar photons”. I know that this is all that we have (currently), but we only have this because we (humans) are in part arrogant and our world view (in space and time) is very narrow and simplistic. Geopolitically, we still have a little middle age in sciences, but this is another song.

BIOSIGNALS. As James Kasting (a genius for me) said, in his excellent review (Kasting et al., 2013(2014) doi/10.1073/pnas.1309107110): “the number of potentially detectable biomarker molecules may be relatively limited”. Now, What if we upgrade (a lot) our remote sensing tech and methodologies (because this is all that we have), and one day in the future, we claim have discovered a planet who have biosignature gases and we assigned a high probability of certainty that those gases are from biogenic origin? What if that planet is optimistically 6 or 8 light years away of us? If we are unable to detect life on or in Mars, even less on Europa, Titan, Venus, Ganymede, etc. Probably (as ESA and Schneider et al., 2010-Astrobiology 10(1):121-126 considers) the next step would be to search for oceans glints or photosynthesis “red edges” in those Exoplanets, but the results going to be the same as Vikings. We are so limited because we want.

We barely can imagine about the diversity of life out of here, because we have enormous economic, political, social, even scientific frontiers and a ridiculous minimal support for do the correct search for LIFE. It seems (sadly) that we need a new world war or a giant asteroid on their way to Earth, in order to advance. Or we need that the “Greed” culture makes hotels in Mars and other eccentric places around the SS. Obviously The "Greed" does and also destroys.

THE CORRECT SEARCH OF LIFE and a bunch of polyps. First, we need a General Theory of Life, at least we need a better definition of Life, but we can’t design one or have one because we are living on Earth and studying Life as if we were the polyps of a coral reef. Polyps live all its life, sticked to its solid calcium carbonate skeleton. That both polyps could know about Life in the open sea, or in the bottom of the sea, or better yet, out of the sea? That both tropical shallow-water coral reefs could know about other species of coral that live in deep-water conditions, from about 50 to 2,000 meters below the surface, where the water is cold, the pressure is high and the local fauna is quite different? Polyps die with little changes in temperature, pH and pressure. No significant tropical shallow-water coral reefs occur where temperatures fall below about 18 °C, or pH falls 0.3 units. We are as weak as polyps and ignorant too. It seems like we from our substrate and below our optimal sea, we are searching for other seas and other coral reefs, searching for clear seas with adequate sunlight and warm salt clean water (The Search for Habitable Seas).

The correct search of Life means leave our substrate and explore the open ocean and deep-waters, means be sure about which nearby planets or moons (In our SS) aren’t inhabited or which one are, means be there robotically or physically (mainly), means better isolation and Life support technologies in order to avoid biological contamination and improve research, means a better use of space resources (asteroids, comets, solar energy, planets, etc.), means to study, in situ, other potential abiogenesis zones (active, latent or extinct), means to experiment chemically and biologically with other planets and moons, means leave our world and colonize and/or terraform uninhabited planets, in order to assure our existence and boost the continuum upgrade of our intelligence.

I'm writing a paper about new options for search of life.

At your orders, I remain.

Sandro,

You say "First, we need a General Theory of Life, at least we need a better definition of Life, but we can’t design one or have one because we are living on Earth and studding Life as if we were the polyps of a coral reef etc.".

Well, I think necessary to recall my viewpoint as I notice you didn't read the previous posts of this thread (which is usual in RG because of the RG format).

The concept of 'life' is questionable (see my paper attached: "Is A n+1 Definition of Life Useful?").

It seems to me that an universal definition of 'life' will never appear because the concept of 'life' is a metaphysical concept and not a scientific one.

Then, is it nevertheless possible to specify an "habitable zone" of a star?

I think it is possible if the researchers give up the concept of 'life' and instead focus on how Darwinian evolution could have emerged on early Earth (see my paper on RG: "Origin of Evolution versus Origin of Life: A Shift of Paradigm").

If so, depending of your hypothesis, it is possible to define a range of conditions.

For instance, according to the hypothesis I propose (i.e., on how Darwinian evolution had emerged on early Earth): "Celestial bodies considered as candidates for the emergence of evolution should plausibly have a very long-standing process of plate tectonics in order to allow the occurrence and maintenance of deep-sea hydrothermal sites such as Lost City Hydrothermal Fields. These constraints would add to classical requirements, e.g., basic ingredients such as reduced carbon-based molecules and liquid water".

Article Is A n+1 Definition of Life Useful?

Dear Kenneth,

I think that your view of the problem is one-sided; Nature is more inventive than you think. Indeed, life could originate underground and with no liquid water. Just such a mechanism was proposed by me and Victor Ostrovskii for origination of the first living beings. As far as I remember, you wrote that you read these works. Meanwhile, paleontological works testify that the first simplest organisms originated about 3,900 Mya and nobody knows exactly whether oceans existed in this period (though, this is not a critical thing for our consideration). As you understand, the solar radiation does not prevent the underground life. By the way, the species diversity before the glaciations of 2,400 – 2,100 Mya was limited, according to the paleontology, by the organisms that could live underground. I am sorry I think that this your issue was written too hurriedly. Isn’t it?

Best regards.

Kenneth,

You assert that "the only plausible mechanism for protecting nucleic acids and proteins (i.e., life) from 254 nm UV destruction is a modest stratospheric ozone screen formed from the photodissociation of water vapor with the loss of hydrogen to space. (not necessarily a 'biosignature' gas'). No other UV-protective mechanisms can be made consistent with the geological and geochemical evidence".

Why don't you envisage the protection by a great height of water as in the hypothesis that Darwinian evolution has emerged in deep-sea hydrothermal sites like the present Lost City Hydrothermal Fields?

Dear Kenneth,

I am surprised at you: really, do you think that dark metabolism is not possible? If this is so, you might offend myriads of underground and undersea-surface habitants.

Today, when about five hundred researchers had visited this page, I allow myself to formulate my own answer to it.

First, about the object of the question. Some of the members write about the possibility of another form of life differing from the Earth’s one. In my opinion, it is possible to talk about any phenomenon only after a rather definite specification of its content, and, when putting the question, I bore in mind no phenomenon differing from the Earth’s life. In my opinion, it is unreasonable to say about something if no one knows what it is. It is my opinion about the reasoning of those who wrote about some nonterrestrial forms of life. Such twaddle has no scientific basis.

A number of the life definitions are known; I prefer to determine this phenomenon as follows: “Life is the phenomenon of the DNAs self-reproduction on the basis of the components of other DNAs and amino-acids associated with them (animals) or mineral substances (plants). We can discuss only such a life and no other, because no other life is known. (As for my own opinion, no other life is possible, but it is a special statement, and it requires a separate explanation beyond the problem under consideration).

A widely distributed opinion that the occurrence of liquid water on the surface of a celestial body is necessary and(or) sufficient condition for life origination on it is mistaken. It is not necessary because living matter may be underground, and it is not sufficient by the several following causes: (1) the occurrence of living matter requires P, N, O, and H but not only O and H; (2) living matter origination requires the occurrence in an accessible proximity of three substances, namely, a hydrocarbon gas-hydrate (hydrocarbon can be CH4, C2H6, or C3H8), niter, and phosphate, because only these three substances taken together are capable of giving DNAs and anino-acids and because meeting together of any four substances at any one point is practically impossible; (3) underground or at celestial body surface, the temperature conditions appropriate for hydrocarbon-hydrate formation should occur.

As for the today surfaces of the Solar System celestial bodies, living matter exists on the Earth only. As for the past times, surface living matter had existed, apparently, nowhere. As for the underground living matter, it cannot be excluded that living matter exists not only at the Earth, but at the Mars as well; however, in my opinion, it can exist there underground only. The absence of living matter at the Mars’s surface was predicted by me and Victor Ostrovskii in the paper published in 2007 (Physics-Uspekhi, 50, 175-196) and this prediction has not been refuted up to now.

Kenneth,

All your riddles and many other ones are answered in our papers available at the ResearchGate site. Read them please if this is of interest for you and if you have time. But don’t choose the shortest papers.

Meanwhile, I invite you to participate in the European Planetary Science Congress (7-12 Sept. 2014, Cascais, Portugal). As a convener of the AB3 Session "The emergence of Life in the Universe from Astrochemistry to Astrobiology and beyond"?, I guarantee you the possibility of discussing all your questions.

As for the today underground living matter, read, e.g., the paper Schippers A. et al., Nature, 433 (2005) 861. As for paleontological works, try to start, for example, from the site http://www.talkorigins.org/faqs/quotes/mine/part1-4.html.

Kenneth,

I am sorry to say, but your questions do not say in your favor. You would like to have a maximum new knowledge quickly, free, and effortlessly. Is it your previous work as a journal editor that taught you this? As for the ordinary researchers, they update, enlarge, and refine their knowledge through hard work. As for the indication of pages and paragraphs, ones usually make this for children who cannot use the searching options. I already made a great deal to help you. I can propose you one more our paper (Physics-Uspekhi, 50 (2007) 175-196), where the Nature paper is referred. By the way, we wrote your name among the possible reviewers for one of our new papers and, possibly, you will have a possibility to amuse yourself.

Regards.

Kenneth,

First, we clarify the only feasible mechanism of living matter origination at any celestial body where the appropriate conditions are available.

Second, we prove that there are no grounds for Oparin’s mechanism, which is the parental one for the Miller-Urey experiments, including the idea of lightening.

Third, the mechanism proposed by us is principally original.

The content and chemical, physical, thermodynamic, experimental, and observational grounds of our mechanism are described in detail in our papers referred in my previous issues addressed to you. Life Origination Hydrate Theory is rather complicated for its detailed description in rather short issues at the ResearchGate pages. You can study it by reading our papers, and, after that, you can put your remanent questions about some its concrete points. I wrote you that the most comprehensive review papers, which can be recommended by me for acquaintance with the LOH-Theory, are V.E. Ostrovskii, E.A. Kadyshevich, The Book: DNA Replication – Current Advances, InTech: Rijeka, Croatia, Chapter 4, (2011) 75–114; V.E. Ostrovskii, E.A. Kadyshevich, Global J. Sci. Frontier Res.(A), Physics and Space Sci., 12 (2012) (6) 1–36; V.E. Ostrovskii, E.A. Kadyshevich, Physics-Uspekhi (Advances in Physical Sciences), 50 (2007) 175–196. The thermodynamic grounds of the theory are detailed in the papers published in Thermochim. Acta and J. Therm. Anal. Calorim.; the corresponding references are in the above papers. All the papers are available in our pages of the ResearchGate site.

If you would refuse to read our papers (at least one of the above listed ones), you could put questions till the crack of doom (“Will the line stretch out to the crack of doom?.. "; W. Shakespeare, ‘Macbeth’).

Kenneth and all RG members,

Life in its philosophical and chemical grounds is the phenomenon of DNA extended reproduction; amino-acids and peptides are the side products of this phenomenon. In principle, DNA extended reproduction can proceed with no amino-acids and with no peptides. Some prokaryotes contain no peptides or the content of the last is minor. The special view on peptides and amino-acids came to today researchers from the 19th century, when nobody knew about DNA as transmitter of hereditary characters. Moreover, in our opinion, the manifestation of the so-called genetic code is no more than the result of autocatalytic polymerization of high selectivity. This idea is expressed in my (with Victor Ostrovskii) paper published in Thermochim. Acta, 458 (2007) 148-161 and republished in the book DNA Replication – Current Advances (Prof. Seligmann, H., еd.), InTech: Rijeka, Croatia, Chapter IV, (2011) 75–114, etc.; in these papers, a detailed physicochemical mechanism for this process was proposed. The ideas of these papers were met with interest by biologists. I can refer, e.g., to the Prof. H. Seligmann Preface to the Book (this Preface is reprinted prior to Chapter IV at ResearchGate). Originally, amino-acids had formed in the super-cytoplasm as side products of the DNA synthesis (see papers cited above). In the course of DNA replication and cell division, the source of amino-acids is nutrition and products of its chemical transformations. As for peptides, their synthesis and their role in the phenomena of life, cell aging, and life prolongation are described in our paper published in “Global Journal…” and, in less detail, in the papers referred above (all the papers are available at ResearchGate). All these and many other details are considered in our papers.

I don't understand why you were “unable to find the answer” to your questions in our papers. He that seeks finds!

Kenneth,

Intentionally or thoughtlessly, you misrepresent my answers. From your previous and last questions, I see that you still didn’t read our papers. I will continue correspondence with you only after you read them. To help you, I specify the papers where you will find the answers to these your questions: V.E. Ostrovskii, E.A. Kadyshevich, Physics-Uspekhi (Advances in Physical Sciences), 50 (2007) 175–196; V.E. Ostrovskii, E.A. Kadyshevich, The Book: DNA Replication – Current Advances, (Seligmann, H., еd.); InTech: Rijeka, Croatia, Chapter 4, (2011) 75–114; V.E. Ostrovskii, E.A. Kadyshevich, Global J. Sci. Frontier Res.(A), Physics and Space Sci., 12 (2012) (6) 1–36.

Kenneth,

About deep-sea hydrothermal proposals you say "Marc…I wrote about deep-sea hydrothermal proposals back in 1991… SCIENCE volume 251, page 142. There are several problems with such mechanisms. Even if one could form a variety of amino acids and then form peptide (or nucleotide) bonds underwater the subsequent growth of those initial bonds to form polypeptides leading to proteins would be difficult. The continuous hydrothermal activity moves the products around in the water column discouraging contact and recontact. The chemistry of these fields and the geological record (banded iron) is inconsistent with the proposals that hydrogen sulfides and pyrites were involved. Clear ocean water is not a very effective UV screen so subsequent evolution of photosynthesis requiring visible light would still be inhibited".

Well, again, since 1991 a lot has been published on this subject. I am afraid you haven't updated your knowledge about it.

For example you say "The continuous hydrothermal activity moves the products around in the water column discouraging contact and recontact".

Ok, but, if the production of amphiphilic compounds composed of aliphatic hydrocarbons (C9-C14), aromatic compounds (C6-C16) and carboxylic acids (C8-C18) have led to the formation of lipid vesicles (as proved experimentally), the products synthesized inside the vesicles would have been protected from the continuous hydrothermal activity (see my 2011 paper you haven't read apparently).

You also say "The chemistry of these fields and the geological record (banded iron) is inconsistent with the proposals that hydrogen sulfides and pyrites were involved".

I am afraid you confound black smokers and white smokers such as the Lost City Hydrothermal fields (LCHF). With regard to white smokers (e.g., LCHF) I must recall you that hydrogen sulfides and pyrites are not involved in these at all.

Again I recall you that LCHF is an extreme endmember in which hydrothermal geochemistry is controlled primarily by serpentinization reactions that produce pH 9–11, temperature ≈ 40–91°C fluids enriched in H2. In addition, these fluids are enriched in calcium. Hence, mixing of these fluids with seawater results in the precipitation of large carbonate chimneys. Actively venting chimneys and flanges are highly porous as they show fine anastomosing networks of carbonate lined with brucite, with tiny interconnected pores on the micrometer scale, indicating the mixing of seawater and hydrothermal fluids within the interior walls. Fluids percolate through the carbonate anastomosing networks. Thus theses very specific local conditions are quite favorable to biochemistry as thermodynamic calculations demonstrate that biomass synthesis is most favorable at moderate temperatures such as at LCHF, where the energy contribution from HCO3 and H+ in seawater coupled to the reducing power in hydrothermal fluid are optimized. Moreover experiments simulating molecular transport in elongated hydrothermal pore systems showed extreme accumulation of molecules in a wide variety of plugged pores. Other experiments demonstrated that thermal gradients across narrow channels can provide the energy necessary to concentrate dilute molecular solutions and thus allow the self-assembly of lipidic vesicles from an initially dilute solution. Vesicles with membranes composed of bi-layers from mixtures of amphiphilic and hydrophobic molecules could have formed from the organic compounds present locally at high concentrations.

Finally you assert that "Clear ocean water is not a very effective UV screen".

Do you really assert that about 750 meters of water is not sufficient to protect from UV radiations?

Dear Marc,

Thank you. He deserves your criticism.

Kenneth,

I see your point which is the question on how the first photosynthetic organisms were protected from ultraviolet radiation (UVR) that was higher than today.

In their paper "On the photosynthetic potential in the very Early Archean oceans" Daile Avila, Rolando Cardenas and Osmel Martin (2012: arxiv.org/pdf/1212.0872) make the hypothesis that "the presence of an oceanic UV blocker such as Fe2+ would have greatly ameliorated the photobiological regime in the Early Archean, creating an environment with a potential for photosynthesis definitely better than that during the Late Archean. In general, photosynthesis rates would have average values in the upper layer of the ocean (where UVR is a stressor) higher than in the Late Archean. The presence of other oceanic UV blockers would still improve this situation, provided their photosynthetically active radiation absorption was negligible".

According to these authors "It is stated that the very first organisms capable of doing photosynthesis were anoxygenic, but then were overwhelmed by more efficient photoautotrophs: cyanobacteria.

At this time, prior to the formation of the ozone layer and perhaps with no other atmospheric UV blockers, the flux of UVR on the ocean surface was higher than today (Singh et al. 2008).

UV radiation has a diversity of damaging effects in microorganisms, from DNA damage to photosynthesis inhibition. Thus, it is often stated that the photobiological regime in the Archean eon (with ozone-less atmosphere) would put a very strong constraint on surface aquatic life. However, an absence of atmospheric UV shields does not necessarily imply an absence of oceanic ones. In the seawater existed several organic and inorganic chemical species that have been proposed as potential UV absorbers in the Early Archean oceans: organic polymers from electric discharges and HCN polymerizations, solubilised elemental sulphur, inorganic ions such as Cl-, Br-, Mg2+, and SH- or Fe2+. An oil slick (formed by polymerisation of atmospheric methane under the action of solar UVR) or large quantities of organic foam would also serve as a very efficient UV protection, see Cleaves and Miller (1998) and references therein. The most important inorganic UV absorbers appear to be Fe2+ and H2S, with Archean banded iron formations providing some evidence for concentrations of Fe2+ much higher than those of H2S. The first has significant absorption in the UV region and was present in the anoxic very Early Archean oceans (Lowe 1982). It would have originated from deep ocean hydrothermal upwelling and could have provided significant UV attenuation for the benthos and mixed layer and intertidal habitats (Olson and Pierson 1986; Garcia-

Pichel 1998)".

Kenneth,

In your 1996 paper "Environmental oxygen conditions during the origin and early evolution of life" I notice you wrote "Prior to this the major protection for the evolving protocells would have been deep water, interstitial sediment habitats, or the evolving matter itself. Mucilage and sheaths of Cyanobacteria and the matting habit of stromatolites are testimony of this evolutionary process". (!).

You also assert that "Phylogenetically primitive hyperthermophile eubacteria grow optimally with the aid of small amounts of molecular oxygen (

Dear Colleagues,

I am forced to write repeatedly some, as I think, obvious questions that relate to the problem of living matter origination, in connection with the alternate pretensions from Dr. Kenneth Towe.

According to our Life Origination Hydrate Theory (LOH-Theory), the primery living matter originated within the methane hydrate honeycomb structure from CH4, and NO3 and PO4 ions underground or/and underseabed.

It is well-known that living organisms are really detected in great quantities underseabed up to the depth of 400m and under 400-5000-m water colomns at different regions of the ocean. Living matter was also detected deep underground in Siberia. In addition, it is known that different living organisms were observed in water in the Mariana Trench at a depth of about 10000 m. All this information is presented in our papers, where corresponding references are given. Meanwhile, Dr. Kenneth Towe writes that no underground living matter is possible. This shows that he does not read the literature on the subject discussed by him and bluffs the members of the community. Mark Tessera also writes in his issue about this.

Dr. Kenneth Towe anew put on a pedestal the Miller’s and Urey’s experiments on the amino-acid syntheses from the H2O-CH4-NH3-H2 mixtures under the electrical discharges; these experiments are based on Oparin’s hypothesis, which was first formulated in 1924. It is well-known that these experiments led to nothing but syntheses of some aminoacids, although many tens of researchers performed similar experiments in different laboratories. Meanwhile, these experiments were senseless and were condemned to failure. Why is this? The detailed answer is given in our papers, and I am forced to repeat it. (1) Oparin thought that the living matter entropy is so low that the enthalpy change is not capable of making negative the free energy change in the course of living matter syntheses from minerals and that, therefore, external energy is necessary. Oparin was mistaken; methane+niter+phosphate are capable of giving DNAs, amino-acids, and, of course, peptides with no external energy. This is proved thermodynamically and is beyond doubt.

Dr. Kenneth Towe does not understand that not amino-acids but DNAs represent the ground of living matter and that just their formation determines origination of life. Amino-acids originate and are being produced in the course of living matter origination and in the course of metabolism as the side products and from those source substances from which DNAs form. However, DNAs are capable of forming within a natural mineral matrix only and the same matrix forms the cellular protoplasm, and, thus, the process of living matter formation is governed by the process of formation/destruction of the gas-hydrate structure. This matrix is exactly appropriates by the sizes of its cavities to the DNA components and to the DNA as a whole. The occurrence of the matrix gives explanations for the structure and composition of DNAs and for the phenomenon of monochirality. Unfortunately, the same I should say to Marc Tessera as well. All the mechanisms of living matter origination and development are described in our papers, and these mechanisms are necessary and sufficient for life origination and development. Each step of these processes is detailed in our papers; numerous thermodynamic calculations confirm them.

In addition, it is necessary to understand that neither single nor rare events of DNA origination couldn’t become the source of life as of natural phenomenon. In order that the phenomenon of life would appear, origination of a multitude of DNAs in close proximity to each other is necessary. Only such an event could be conducive to development of life as phenomenon and to symbiotic interactions of primary DNAs.

The LOH-Theory allows for answering the following questions. (1) In what phase did the LMSEs form? (2) From what substances did the LMSEs form? (3) By what mechanism did the N-bases, riboses, and nucleosides form? (4) Is Nature capable of synthesizing LMSEs from minerals with no external energy? (5) How had methane hydrate originated? (6) How had CH4 and NO3– met together? (7) Why no substance but NO3– reacted with CH4-hydrate? (8) How did DNA- and RNA-like molecules form from nucleosides? (9) Is there a relation between DNA and RNA formation, on the one hand, and the atmosphere composition, on the other hand? (10) Why do only five chemical elements usually enter the DNA and RNA composition? (11) Why are N-bases entering DNA and RNA similar in their composition and structure? (12) Why are N-bases and riboses limited in size? (13) Why are N-bases not identical? (14) Why do only five N-bases usually enter the DNA and RNA composition and why do other N-bases, such as xanthine, sometimes enter the DNA and RNA compositions? (15) Could D-ribose (DR), desoxy-D-ribose (DDR), thymine and uracil exist simultaneously in a reaction mixture containing CH4 and niter? (16) How had it happened that the sequences of N-bases in DNA and RNA molecules are not random? (17) Why did Nature choose DR and DDR, but not their L-enantiomers or mixtures of enantiomers for DNA and RNA syntheses? (18) How did protocells originate? (19) What is the cause of the explosive appearance and development of living matter late in the cold periods of the Earth’s history? (20) Does living matter exist on other planets? (21) What is the cause of exclusive powerful events at the Sun, and what are their consequences for the Earth? (22) What powerful events at the Sun are expectable?

Of course, it is senseless to propose our paper for reading to the persons like Dr Kenneth Towe who knows in advance how living matter originated and develops. I propose to do this to the researches free of dogmatism and capable of logical thinking and analyzing different sides of these phenomena.

I can’t discuss with Dr. Kenneth Towe personally because he is a rude fellow. Earlier, he was very rude to me, then he begged my pardon (I saved these files); however, two-three days ago, he corresponded with my colleague Elena Kadyshevich in improper form again. Meanwhile, if any idea is not liked by a researcher it doesn’t mean that this researcher should be rude to its author. In addition, he expresses himself in contemptuous form about papers that he refuses to read. Mark Tessera and Elena Kadyshevich also noticed this feature of him.