Exactly. It seems intellectually stimulating to grasp that point. Imagine the machinery and flexibility of evolution if it was indeed a single ancestor for all life. If so, where would we draw the line to define cousins?
That is the question that is not yet answered. If it is true, then the evolutionary stream of events for bacteria, archaea and eukaryotes is parallel, all diverging from this single cell we are calling LUCA. Do you have a source for the statement I quoted above from you?
And that is why I stipulated at the outset that we would not deliberate about how LUCA or LUCAs arrived. Certainly it was necessary, but after that occurrence, was only 1 sufficient?
LUCA is of course a single entity. But there could have been, might have been, a LUCA for bacteria, another for Archaea, and another for Eukaryotes. In fact, no matter how we define LUCA, she was clearly not the first life. That was the stromatolites layerd down in sediments my microbes a billion years before complex life. My question was directed toward the issue of whether or not there is evidence for one rather than multiples. At least that is my understanding.
Yeah one is what I would expect. But in principle if reproducing life got started at an one ocean vent, why couldn’t it do the same at another? If the origin sites were sufficiently isolated more than one line could eventually get started. Of course if indeed all other life did evolve from these, once they were free from the vicinity of their home vent which ever was better adapted could then clear the field.
Why this should matter a great deal is beyond me. Since these new guys are so comfortable discussing universal deficiencies of all atheists I feel entitled to speculate that they are on a fundamentalist mission to find a new knock out argument for ‘proving’ God. Meh.
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Why not? How could it possibly be otherwise?
Where do you get that from? There is only evidence for one for all life on Earth now and for the past 4.5 ga.
No. While it is true that the number of our ancestors cannot exceed the total population which varies, this does not support your claim that ancestry of a population converges. Perhaps you are mislead by the studies of mitochondrial DNA and Y chromosomal DNA. Because these are obtained from only one parent, then genetics can only converge. But that is only a very small portion of our genetics.
That you can imagine such a thing does not establish your claim. The genetic evidence does not support your claim either. The smallest population bottleneck the evidence allows is thousands of people not two people.
What we have instead is examples of what happens as a result of human inbreeding: “genetic disorders associated with inbreeding include schizophrenia, limb malformation, blindness, congenital heart disease, and neonatal diabetes .”
The reason that I wanted to bypass that issue, whether God or nature is responsible for the first life, is because to do otherwise creates and allows for distraction from the issue I posed. That issue was to debate whether there was a single or multiple origins. I was simply trying to eliminate a variable. It was NOT in any way meant to ignore the issue of intelligent design.
Indeed, every treatise on the topic refers to Carl Woese’s theory posed in 1990. In the books, In Search of Cell History (Harold) and Stairway to Life (Tan), this is discussed, but is far from conclusive, and still debated today. That is why I posed the question for this esteemed group.
In Atheism World, I should think some sea-water and a bit of heat is more than enough to produce a veritable smorgasbord of living organisms. 
It is not a claim, but rather my intuitive reasoning. If there is a first living “anything”, the first of a new species e.g., then all progeny diverge into the numbers found today (plus those born > died). Following the same process in reverse converges into the one.
To be clear, I am not talking about convergent evolution, where two different taxa independently evolve the same phenotype (wings on insects and birds). My thought is in the reverse direction, trying to find a single LUCA for each species, or more likely a single common LUCA for all domains. That is my question, and is not a claim.
I was looking further back, before the major two bottlenecks of Toba (75,000 ya and Campi Flegri 40,000 ya). Those events shrunk world population of Homo sapiens lineage, but at some point, perhaps long before that, there had to have been fewer, as we retreat to the H. sapiens branch of the “tree of life”. But my question was that as we go further, to larger and larger branches closer to the base, do we find an ultimate LUCA?
I’m an atheist, and I would be just fine if LUCA was a group of different ancestors. The important thing for me is the evidence.
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Your are stuck in the paradigm of vertical inheritance. Horizontal inheritance is a very real thing among the simplest life we see today, and there is every reason to believe that it could have occurred early in life’s history.
This is why LUCA as a single species probably doesn’t make sense. We are probably looking at a root ball at the base of the Tree of Life.
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Not at all. In fact, I mentioned the role of LGT many times. But that has NOTHING to do with my question of whether there was only one beginning of life or many. Nothing whatsoever. LGT is the concensus method and perhaps the only possible way to incorporate both informational and instructional nucleotides into a living genome. E.g., plastids almost certainly came from chloroplasts.
And in knee-jerk, mind-dead fundyland straw manning the other side is so ingrained that listening becomes a lost art. But do note I don’t paint all believers with one big brush; there is nothing about your playbook that appeals to me.
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Before the evolution of genetic code with ‘high fidelity replication’ and ‘and at least some rudimentary early form of molecular proofreading’. I.e. LUCA.
Which is of a single organism. Among many that didn’t make it.
My question was with regard to the sufficiency of
the evolution of genetic code with ‘high fidelity replication’ and ‘and at least some rudimentary early form of molecular proofreading’. I.e. LUCA.
Why bring God in to this by putting Him aside for now? Which is what you appear to be doing. He is not necessary in the slightest in the process of abiogenesis any more than He is in stellar nucleosynthesis or self-tuning.
Once we had Theobald’s (2010) and Saey’s (2010) LUCA there was no possibility of gene transfer from any other LUCAs.
For the upteentth time, my question presumes the opposite. My question (one or many origins) intentionally leaves aside the nature of the origins, but only addresses whether (or not) one original living cell is sufficient for all the life we see today. So I am NOT either “bringing Him in” nor “leaving Him out” in any way. I am simply pondering what occurred AFTER we found a cell (or cells) capable of all that we agree is necessary for it to be considered life. It seems obvious that you are simply trying to be adversarial, contentious, argumentative, petty and/or pick-nits. Why can you not offer a thoughtful opinion on the topic I posed?
Regarding lateral gene transfer, it is logical to me that this is a reasonable mechanism for cells to acquire different organelles and evolve. But my question precedes those LGT events. LGT helps explain evolution, but not whether it all began with a single living cell.
My original hope was that posing the question as I did would allow this forum to by-pass questions that disturb and divide atheists and theists. It was to get further downstream to the point that we could all agree on one thing: “It did happen” without regard to “who was responsible”. So since it did, let’s follow the evidence and understand it better.
That image helps me. It looks as though for a while whatever variety of progenitors life as we know it may have had, up until some point, sharing/stealing of genetic assets was rampant. After that it still occurs but not so pervasively. Are the reasons for this well understood? Might it be that at that point all or many organisms would have garnered the capacity to keep those resources better protected? Also how far would DNA duplication go back? Would that have existed in the ‘primordial soup’ itself before membranes separated individual organisms?
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