I believe that all life that has been, so far, studied on Earth is descended from a single, original organism, that at some time in the very distant past it arose, constructed from non-living matter, functioned as a living organism and, for some unknown reason, in some unknown way, produced viable, successfully reproducing offspring. I believe that from the evidence of genetic similarity among extremely distantly related species found in the highest, yet assigned taxonomic groupings of domains living today, from the available fossilized evidence and from what seems to be reasonable conclusions of probability founded in what evolutionary science has reliably established.
I believe from what I've said so far that one thing can be known about this proposed common ancestor of all known life, that unlike every last one of its descendants it did not come about from biological reproduction. Its origin is in a process which is unknown to biology.
That is true even if, as some of the frustrated "abiogenesists" have proposed, the introduction of a living, first organism on the ancient Earth was by meteor impact. That would only put the actual origin of life on some other unknown, planet or planetoid, it doesn't get us any closer to an answer to the question.
And, there is one more thing that can be known. The actual original organism arose in an actual event, an event that happened in the one and only way it happened. In one way, in one place and by unique processes which we don't know and of which we have absolutely no physical evidence. That fact really is all important.
Getting ahead of myself, whatever those actual, historical events and circumstances were like, one thing that seems eminently reasonable to conclude is that it was not under laboratory conditions under the care of scientists. The real conditions under which life arose are entirely unlikely to be reproduced by scientific experiments in the 1950s or down to today. Call me an enemy of faith but I will not entertain the consideration of the too close cousins of Scientology that make up myths about life on Earth being put here by extraterrestrial scientists. That, again, only puts off the sad hour when the "science" of abiogenesis has to face that it can't do what it was invented to do, support the ideology of materialism with an accurate, materialistic account of the actual origin of life on Earth.
From those facts and the resolvable, available micro-fossil evidence I accept that life began in the very early Earth, probably more than 3,500,000,000 years ago. I accept that the conditions under which it arose are far, far different from those we know with enough detail to enter into science from much later periods, including our own. Given the enormously long period during which it might have arisen and the expectation that conditions on the early Earth were probably quite variable in different locations, I don't believe we will ever really know what those conditions under which life began were like. From that same micro-fossil evidence and the problems of the first organism being multi-cellular and having the complex cellular chemistry in all known organisms today, I believe it was far, far different from even its very ancient single-celled descendants.
You may notice that all of what I've said so far is expressed in the form of the creed, I believe, because that is true. The evidence my belief depends on is no closer to the presumed beginning of life than hundreds of millions of years after I believe it began. Any conclusions I make are informed by the fact that later life is known to have evolved, sometimes dramatically, during much, much shorter periods of time. This is especially true of some kinds of microscopic life. There is absolutely no evidence of what the original organism, that I believe was the unique, actual, origin of life on Earth because there is no physical record of that.
I do believe that if life arose more than once it would be miraculous, if separate lines developed from different original organisms to produce genetic similarity in its descendants, today, I can't see how anyone could rationally reject the idea that it was a miraculous and intentional act. If that's the case then science can't deal with that aspect of it. It merely seems to be unlikely to have happened that way, I can't honestly say that I know it didn't happen that way because of a lack of evidence. As I said, above, my conclusion is that there was a single original ancestor of all known life on Earth, the only place in the universe we know where life is found.
BECAUSE OF A LACK OF EVIDENCE
An atheist, "Candian Skeptic," got very angry with me over at Huff Post last week because I honestly admitted that my belief in common ancestry was a matter of faith, not science because of a lack of evidence of what that common ancestor was like. My faith is based in a knowledge of evolution, the commonality of genetic materials, the lessons of geology and what I presume are correct ideas of the probability of events happening. Those ideas of probabilities aren't based in any actual facts from the earliest life but are imposed out of what is known from later life. For all I know none of that is actually relevant to the unknown. Even what I believe about the mathematical probabilities concerning the origin of life is an act of faith. Real probabilities would depend on far, far more information that is unavailable, which I believe will always be unavailable.
In discussing the origin of life with science oriented atheists, all of them materialists, I've found that they are uniformly more driven by faith to make wild assumptions about what that was like than I am. I think I've gone farther than the real evidence of that than can support anything honestly classifiable as knowledge, they, on the other hand, are prone to really believing that the now ancient and scientifically disputed work of Miller and Urey, and even the earliest, clearly ideological, claims of Oparin are actually relevant to the origin of life on Earth. And if not those then more recent, far from uniformly believed, assertions made by later scientists.
It seems to me that when you are dependent on belief, without any evidence, it is far more prudent to believe in the simplest case possible with the fewest details, minimizing the amount you have to believe in to come to conclusions about it. Tellingly, the atheists, materialists, who are true believers in one or another of the creation stories of abiogenesis believe, quite emotionally, in far more than I would ever express. And, most tellingly of all, they believe that their faith is reliable science.
In some of the most extreme expressions of that atheistic faith, I've had a number of atheists make arguments about the the "OoL" out of DNA or RNA, only there is no evidence that those molecules were present in the original organism. I'd like to know where those were supposed to come from, unprovided by biological action, in what is likely to be a very inhospitable environment, assembled out of what were very weak solutions of unknown chemicals. Not to mention how those came to work, perfectly, in the absence of the very complex cellular chemistry necessary for them to function. Where did a containing membrane for such a complicated common ancestor come from? How did that membrane divide for the first time in an act of reproduction and reseal itself in both the "original" organism and in its first offspring, an act of what would almost certain to be the most complicated chemical and physical act to have ever happened on Earth (or on which ever planet or planetoid it might have happened on). I don't believe, for a second, that the common ancestor had anything like that complicated structure or chemistry, not unless it was the product of a far greater intelligence than our best scientists have today. I believe that the cellular biology we know today is the product of evolution within living organisms. If I believed in what those atheists assert, I'd have to believe in intelligent design of it. If I did come to that conclusion, I would never assert that it was science.
And every, single other proposal of how life originated on Earth I've read, to date, has either an extraordinarily unlikely chemical complexity, extremely speculative conditions - preposterously speculative, at times - or other problems with their seeming probability. None of them has anything like an enduring, majority acceptance among even the true believing "abiogenesists". That field seems to produce splinter factions like Freudian psychology and American communism does. Sometimes the intra-scientific sniping reads like that found among schismatic sects of Baptists.
It's rather odd to be in a position to be able to scold the atheists due to their faith holdings based in a total lack of evidence asserted to be science. But there is nothing that so easily shows that these atheists presenting themselves as the only and true champions of ultra-rational, hard-headed, "only the evidence will do" science-science, clearly inserting their ideology into proposed science in order to arrive at a predetermined result to prop up their atheism.
I am convinced that was the goal of Oparin in inventing the "science" of abiogenesis and for many if not most of, if not all of, its major figures. I don't believe that "abiogenesis", if it is presented as revealing how life originated on Earth is honestly held to be science. There is no way to test any of the many versions of that origin against the actual event or, indeed, any evidence. No matter how impressive its eventual products might be, they will never have the support of evidence of the original organism which likely was consumed by its descendants, or reduced to a dispersed smear of chemicals or which is forever lost in the enormous mass of geological change over the past 3.5 billion years.
Unlike inert chemicals and even some very complex chemical reactions, when you are talking about living organisms, with their life history, their particular structure and chemistry, their interaction with what becomes an environment due to their being alive and the mere facts of chance during their life, you can't make generalized assumptions. An organism has a far, far more complex identity than molecules and elements that can be considered as typical by science. You can't really produce science about a real, entirely unique, original organism without definite knowledge of those things and that is entirely unavailable for the very unique original organism that both I and the abiogenesists believe in.
I would expect that as soon as a mechanism of inheritance susceptible to mutation was present in the line of life that arose from that organism, that evolution began. I would guess evolution began far earlier than the first resolvable fossils by many tens of millions of years. Given the speed with which modern, single cell organisms evolve, I would expect that the rate of evolution in those years would have be extremely rapid, within organisms unlike those that survived, produced diverging lines that would eventually produce everything from the modern classification into domains, kingdoms, families, ... right down to subspecies, varieties and the very unique individuals that modern organisms truly are.
In thinking about "abiogenesis", "exobiology", "evolutionary psychology", and other products of the applications of materialist ideology purported to be biological science, I've been struck at how much more faith those require than I'm comfortable with including within science.
All of them make the most extravagant possible claims out of anything from evidence inadequate to support those claims to a complete creation of "science" lacking any evidence, whatsoever that its products exist in the natural universe. And there has been the same kind of materialist ideology inserted directly into evolutionary biology, from the beginning, as demonstrated by the citations of Darwin, Huxley, Haeckel and Galton. That insertion continues, almost entirely unremarked, down to today. The, thankfully, unsuccessful attempts to insert Intelligent Design and the even more obvious forms of creationism into science, would have to be absolutely up front in order to serve its purpose. As can be seen by anyone who looks honestly at those "sciences" ideological materialism has a far higher rate of success in being presented as science, accepted by scientists and others who are predisposed to make the huge leaps of faith necessary, pretending that the lack of evidence isn't important. I think that materialist ideological pollution of science plays a major role in reducing the reliability of what is asserted as science, it brings science into disrepute. As can be seen in the question of the actual origin of life on Earth, it certainly brings into question the role of evidence in what is accepted as science.