Is ID falsifiable by any kind of experiment?

Even though everyone on the planet is descended from a single man or woman, that man and that woman (who did not live contemporaneously) were not the first man or woman, and there were many other people alive at the same time. They just happened to be the only man and woman who left descendants alive today.In the same way, UCA was not the first life. It lived within a thriving community of life, probably widely varied with many species and genuses and so on. It was just the only life that left descendants.For there to be multiple UCAs there would had to have been more than one independent origin of life. This is certainly possible, but only one of these origins of life left modern descendants given the relatedness of all life today.But let's say that UCA fails, that we find a branch of life that is unrelated to all other branches of life. That wouldn't cause us to "reconsider our origins" in any significant way. It would a fascinating discovery, but also a kind of shrug, as in, "Oh, life originated more than once - figures." In fact, it would make sense that on the early planet life began and failed multiple times before finally persisting, and that life originated and persisted more than once is not a terribly novel thought.If there were multiple occurrences of the "first life" then just as early humans apparently outcompeted and drove extinct all other hominid species, it is likely that some "first life" was more competitive than other "first life" and drove it extinct, explaining why we have so far detected only one UCA.By "reconsider our origins" did you mean we should consider religious explanations? No scientific puzzle has ever resolved to a religious answer, so why would the origin of life be the first? You don't think other scientific puzzles should consider religious answers, do you, such as unifying quantum theory (the theory of the very small) and relativity (the theory of the very large)? The term "intermediate species" can be misleading because it implies a species is in a transitional state from one species to another. The reality is that no species is fixed or permanent. They're all transitional. We drive stakes in the ground that we call species. Any life currently alive we call a species, and any fossil type that is plentiful in the fossil record we also tend to call a species, but those fixed points that we choose occur on long lines of change, and picking any particular point on that line and calling it a species is arbitrary. Every point on that line represents a fully formed species that is also in a state of change. There is no species in the history of life that remained the same species forever. It gradually evolved and changed or went extinct. Change is impossible to prevent, for even if the environmental pressures remained static there would still be drift since almost every reproductive event includes mutations.--Percy

I apologize that we were confusing. Granny Magda shortened LUCA to UCA, I don't know why. We're actually talking about the Last Universal Common Ancestor, also known as the Most Recent Common Ancestor. dwise1 introduced the proper term, LUCA, prior to that back in Message 475. Those are reasonable numbers, but what's more important is the number of mutations per generation in a population. So with a population size of 1 there would be only 0.003 mutations per generation, but with a population size of a trillion there would be 3 billion mutations per generation.Is a trillion a reasonable size for a bacteria population, say a staph infection? If one bacterium weighs 10^-12 grams, then a trillion of them weighs one gram. Did you know that that only 10% of our bodies are human cells? The other 90% of cells are bacteria (bacteria are much smaller than human cells and represent a small percentage of our total weight or volume).The average human being carries more than a quadrillion bacteria (closer to a hundred quadrillion, but let's use the smaller figure to make it more difficult for me to make my case). If we use a very slow bacterial replication rate of one generation per hour then 3 billion mutated bacteria are created in your body every hour, or 72 billion per day. Is that enough mutations for you? In just your body alone? And with 8 billion people in the world that's 5.8 × 10²⁰ bacterial mutations per day just within human bodies alone.And humans are only a tiny percentage of the total biomass of the earth, so there's all the bacteria in all the other animals, then there's all the bacteria in plants, and then there's all the bacteria that live outside other life. I won't even try to guess how many bacteria that there are in the world, but safe to say that an astoundingly huge number of newly mutated bacteria appear every day.An example of an effectively evolving bacteria is the tuberculosis bacteria. There are quadrillions and quadrillions of them throughout the world creating enormous numbers of mutations, usually SNP's, that occasionally have better success in certain kinds of environments, such as in the presence of tuberculosis drugs. There are now some strains of tuberculosis that are resistant to all currently available drugs. And this despite just 0.003 mutations per generation, or probably less since the mutation rate of the tuberculosis bacteria is low for bacteria.Multicellular organisms tend to have much larger genomes than bacteria, and they produce many more mutations per reproductive event. For instance it is estimated that the average human baby has around 75 mutations (you'll see different estimates cited - when I look this up I typically find numbers ranging from 40 to 100). Of course our generation time is very long, so we evolve much more slowly than bacteria. Unicellular life does age, but many bacteria are effectively immortal except that they have to compete for resources just like all life. For example, ask yourself what happens to gut bacteria when the host animal dies? The environment where they formerly flourished is gone and they eventually die. Or what happens when the small pool of water that was the bacteria's home dries up. They die. I think it very unlikely that any LUCA clones could have survived until today. Even if at one time the ancient earth held quadrillions and quintillions and sextillions of LUCA clones, environmental conditions have changed dramatically since then and would be unlikely to favor the survival of that life. But why do you think the presence or absence of LUCA clones today support your position? Certainly if we found some (I don't know how we'd know we had one even if it were sitting under our microscope) it would be an astounding discovery but not particularly germane to the argument you're trying to make. Any mutations that happened to be beneficial, which some mutations will be, would provide a survival advantage for their cells, enabling them to outcompete other cells, eventually replacing them. We actually witnessed this process of beneficial mutations outcompeting the unmutated versions with the covid virus. Delta outcompeted and replaced the original virus, omicron outcompeted and replaced delta, and BA.1 and BA.2 outcompeted and replaced omicron, and there have been subsequent ones that replaced BA.1 and BA.2. Again, I think we should be using the term LUCA. Given the information I've provided, what do you think now?--Percy

It's always nice to have a little irony in the morning. It can be UCA if you like, but you seem to be confusing it with first life, e.g.: Perhaps "There's not enough information to know the answer" might be a better response. One possibility is that life arose in an environment rich in organic molecules that would serve as food, so while the "non-living" appellation might be deserved, it isn't inorganic detritus.But you had claimed that the first life would populate the entire globe and ignored that there were constantly changing conditions and environments and hazards and competition. This is what PaulK pointed out to you in Message 493 and that you quoted here, but your response didn't address the objection. It actually does address your point, which was that the mutation rate is too slow to produce beneficial mutations. But when trillions and quadrillions and sextillions of cells are involved the number of mutated cells with potentially beneficial mutations is enormous, enabling them to outcompete the original populations. You can't pretend the covid virus mutations didn't replace previous less competitive versions of the virus in short order, mere months, because such huge numbers of viruses were involved. Something similar was true of cellular life on the ancient earth, except that the timeframes were enormous. We know LUCA was adopted to conditions present on the earth at that time, and those conditions do not resemble the current earth at all. Conditions today are unlikely in the extreme to be hospitable to very ancient life. One big difference is that the ancient earth had an atmosphere consisting of gases like methane, sulphur dioxide and carbon dioxide. There was very little oxygen. Oceans were very different in composition, too. Either I don't understand you or you've got the tree of life analogy backwards. The most ancient life is down by the roots. The most modern life is out by the ends of branches. The top part of the tree is today. The roots are where UCA and LUCA are.The fate of most life is extinction, some with a trace, but most with no trace. What you're claiming to find peculiar is normal. Extremely few species or genuses have survived unchanged for hundreds of millions of years that we know of. You are right that species and genuses of creatures that looked much like modern mosquitos and spiders existed long ago, they just weren't the same ones that exist today. Snakes have only been around for about 130 million years, but I guess if you're not too picky anything that is long and tubular and slithers on the ground is just a snake. And about crocodiles, did you know that there used to be hundreds of species of crocodiles but that today there are only 24?Very, very few species have existed unchanged for hundreds of millions of years. As inevitable genetic change takes place over the generations, only ecological niches that exert the same or very similar environmental pressures can keep species molded into something very similar to what existed long ago, meaning they appear to have experienced little morphological change even though there's been a great deal of genetic change. Horseshoe crabs are one of the few exceptions, one species thought to have existed for hundreds of millions of years. But like I said, it's an exception. It doesn't have much company. Fossilization is extraordinarily rare in most environments, and some things even more rarely fossilize, such as anything small or soft. Evolutionary change is a response to environmental pressures. Species in a very stable environment will only experience genetic drift, while those in rapidly changing environments could experience either rapid evolutionary change or extinction. What we see in nature is evolution everywhere, with every species population running mutational experiments up the flagpole to see how they fly.You seem to be asking why don't we see the same types and rates of evolutionary change everywhere. That's like asking why the weather isn't the same everywhere. No one thinks any particular line is experiencing more beneficial mutations than any others, and what's beneficial is relative. Thicker fleece in the north is a real boon, but in the south not so much.What does happen is that a population that experiences a mutation that produces better adaptation, which means improved differential reproductive success, will be better able to compete and will likely produce more offspring, the ultimate determinate of success. I don't know why you're saying this. There's no indication that the human lineage experienced a different mutation rate than other related species going back to the chromosome fusion. Common ancestry is the only way life has ever been observed to come into this world, going back thousands and thousands of years with no reason to think it has ever been any different. What evidence are you looking at that indicates to you that at some time in the past life didn't descend from previous life? Well, yes, exactly. What observations call common descent into question? That's like saying "We need air to breath" is a reasonable narrative. Nothing is orchestrated in evolution. Mutations aren't ordered up as needed. They occur randomly. If they're bad, which they usually are, then they do not fare well. If they're good then they do fare well. If they're neutral then genetic drift governs what happens to them. That's all.The argument you're trying to make is clear. You're saying that the variety of tempo and pace in evolution indicates that it doesn't explain our observations, but you can't produce any observations inconsistent with it. And you're expressing doubt about common descent but cannot come up with a single example of life that isn't a result of common descent.--Percy

I'm replying again because I think my first answer to this was incomplete: ​
First, bisexual life never leaves behind "unaltered descendants." The mixing of sexual chromosomes guarantees that can't happen.Second, after the fused chromosome mutation both descendant species, the one that hadn't experienced the chromosome fusion and the one that had, continued experiencing mutations and evolving at the same rate as previously. The unmutated species did not cease experiencing mutations or experience them at a slower rate. The mutated species did not begin experiencing mutations at an increased rate. Both descendant species continued to experience mutations at roughly the same rate as previously.The chromosome-fused species that eventually became us did not much resemble us when the fusion occurred. And the species that did not experience that fusion did not much resemble whatever it eventually became, assuming it didn't become extinct.Third, of course when the chromosome fusion mutation event was in the recent past that species still greatly resembled its parent species. Other factors being equal, a mere hundred thousand years of evolution will produce far less change than millions.--Percy

Here's another request that when you reply to more than one message at the same time that you make clear which one you're replying to. A better question is why you think this is a reasonable question to ask. There are many species that have gone extinct in just the last 10,000 years for which we know no specific cause. We presume their circumstances changed. Why do you think we should know what caused the UCA extinction event billions of years ago? This is your opportunity to describe how you looked at the data and tested the hypotheses, and what your findings were. Intelligent design was found to be a transparently religious repackaging of creationism in Kitzmiller v. Dover Area School District in 2005. It is my hope to remain a participant and not have to shift back to a moderator role. If life arose only once as a single cell then UCA and the first life are the same thing, but the "one cell once" hypothesis is considered unlikely. There are other more likely possibilities, such as that life arose gradually as one or more populations of self-replicating molecules (possibly RNA) that gradually became increasingly complex. You were wondering how mutation could cause the original unmutated variants to be replaced, so I provided covid as an example of exactly that, of mutation producing improvements that allow one variant to outcompete and replace other variants. The principle for bacteria is precisely the same, for which I provided the example of tuberculosis evolving drug resistance. The important concept is branching with the flow of time being upward. If you present your examples of life that didn't come from previous life then we can assess them. In very broad terms, as we trace life back in time through the fossil record we find that warm bloodedness disappears, then air breathing disappears, then vertebrae disappear, then multicellular life disappears, the signs of life itself disappears. The early naturalists found that species were exceptionally well adapted to their environments, and the theory of evolution was developed to explain that exquisitely fine-tuned adaptation. In effect life is constantly carrying out mutational experiments in real world situations, and those mutations that improve adaptation carry forward to the next generation.--Percy