MarioNovak wrote:Thank you all for your answers but unfortunately they realy have little or no relevance to what I said in my argument.
Respectfully I have to question whether you made any effort to understand what was written to you. You claimed several key components of extant sexual reproductive systems were strictly needed or reproduction would be, in your words, impossible.
Several posters including myself have now pointed out with multiple examples that there are species in existence, now, today, that lack many of the key components you listed.
I myself also explained to you, that you are not properly appreciating the evolutionary history of contemporary sexually reproducing species. That what might seem to be an absolute requirement for the function and reproduction of some extant organism, like human beings, was lacking or altered in distant ancestors. Case in point: Fish that lay their eggs on the bottom instead of retaining them inside.
All our ancestors in the mammalian clade gave live birth, meaning they retained the eggs. But there was a time when our ancestors weren't even mammals, they were reptiles. They laid eggs on the ground. No uterus needed. Even further back, before they were reptiles, they were amphibians. They laid egg in shallow waters. It was at this stage we see our kind of "internal insemination", at least in our direct lineage, for the first time. Back then, there were no strict requirements on the cervix to produce sperm transport-enhancing mucus, because the sperm was simply released over the eggs into the environment.
Before amphibians, there were fish. Some species of fish simply eject their gametes into the ocean and let them mix and fuse right there.
The point with all this is that you are not properly appreciating that alterations to the extant reproductive systems were accompanied
by compensating alterations to the fundamental behavior and physiology of the whole organism. When we go back far enough in evolution to a time when we start to see components missing from extant human and mammalian reproductive systems, we are so far back in time there were no mammals at all, much less humans or primates. The whole damn organism was different, it lived in a totally different environment with a whole host of different opportunities and constraints.
What might be strictly required for
human reproduction is emphatically
not required for
sexual reproduction in general. MarioNovak wrote:First, asexual reproduction that does not involve the mixing of two different genomes, also needs some core components to function. For examle, most bacteria rely on binary fission for propagation. Before binary fission occurs, the cell must copy its genetic material and segregate these copies to opposite ends of the cell. Then the many types of proteins that comprise the cell division machinery assemble at the future division site. A key component of this machinery is the protein FtsZ. Protein monomers of FtsZ assemble into a ring-like structure at the center of a cell. Other components of the division apparatus then assemble at the FtsZ ring. This machinery is positioned so that division splits the cytoplasm and does not damage DNA in the process. As division occurs, the cytoplasm is cleaved in two, and in many bacteria, new cell wall is synthesized. The systems for order and timing of these processes are also needed.
I have to note here that you have now moved away from the specific examples you provided in your opening post, and now erected the same type of argument, but wit other structures instead. This argument now attempts to make the same case for the fundamentals of cell division, that there can be no such thing as cell division without a host of extantly found cellular processes and structures. You are now attempting to argue that instead of large, multicellular structures and mechanisms, that even the mechanisms found inside single cells when they divide, are absolutely required for fundamental cell division to function.
Well actually, no they aren't. To appreciate how cell division originated, we have to understand that lacking many of these key mechanisms go back to some of the earliest stages of life. At those stages, their lack was again compensated for by alterations in the fundamental functions of the organism.
The Szostak lab has successfully demonstrated that primitive cell membranes can make copies of themselves without the aid of advanced protein enzymes and structures. Go here for their publications:
http://molbio.mgh.harvard.edu/szostakweb/publications.htmlMarioNovak wrote:So, if we reduce core components of the systems that allows the execution of these processes - DNA replication, DNA segregation, division site selection, invagination of the cell envelope and synthesis of new cell wall... - the biological process by which new offspring is produced will be stopped, just like with sexual reproduction.
Yes, in extant life.
Back in the ancient past, before 3.5 billion years ago when these mechanisms first originated, before the last universal common ancestor, cellular entities were much simpler. Segregation of replicated genetic polymers were through nothing but diffusion, a simple physical process. As primitive cells grew larger because over-expression of genetic products (lipids, genetic polymers) they would eventually become unstable because of their large size and split in two. The contents of these so-called protocells would diffuse out and equilibrate within the confines of the primitive cell membrane, that means the multiple copies of their genomes would not be
required to be anchored to the membrane by sophisticated protein machinery, they would simply diffuse all by themselves through simple physics. When the cell then broke apart by splitting in two, the contents would be randomly distributed between the two daughter cells.
MarioNovak wrote:Next, labeling some scientific observation "irreducible complexity" does not negate the observation. If we reduce core components of system that enables man to pass semen out of his body and as a consequence reproductive function cease to exist in that organism it is completely irrelevant how we label this consequence because reproduction is not dependable on human linguistics and language, but on the presence of the core components of the reproductive system.
Who has made this about language? I don't care what you call it, the fundamental flaw in the argument remains the same. It just so happens others have attempted versions of this argument before you, chief among them ID-creationist Michael Behe, who called such arguments, arguments from "irreducible complexity". He or you could call it whatever you wish, I and many others have exposed the central flaw in all these kinds of arguments before:
It does not matter that you can eliminate components of extant systems and then break the function of the extant system, because back when these components were actually missing, the
remaining components of the system also functioned differently. The whole system remained functional, because of compensating changes to the then-extant components.
MarioNovak wrote:Also, if reproductive system of some organism is structured so that component X(eg testicles) is neccesary for its function than assertion... "You're neglecting to consider that ancestral species who lacked some of these components weren't using the same kind of sexual reproduction we do." ... is like saying "my PC can compute without microprocesor becouse Babbage's Difference engine lacked microprocesor and was able to compute.
Yes, yes it is,
and that would be correct to say. You can have computation without a microprocessor. You can have sexual reproduction without a human ballsack.
MarioNovak wrote:So this assertion is complete non sequitur that ignores structural and configurational constraints of the system in question. Simply put, you can't accumulate genes for testicles and reproduce if reproductive system is structured so that testicles are needed.
But back before testicles, the testicles weren't needed, because the system in-place back then was functioning in a different way, functioning perfectly well by the way, because the whole organism was was totally different.
MarioNovak wrote:From the study of the natural world based on facts learned through experiments and observation we know that all cellular life forms without exception, from archaea, bacteria to eukaryote will go extinct if we reduce core components of their reproductive systems.
Yes, core components that have become necessary for how they function
today. The
ancestral components have changed through evolution in ways that make them fit together in new ways today. So if you suddenly remove one component, the EXTANT system will break down. But back in time, when that component didn't exist,
the ancestors of all the other components were different, which allowed the system to function perfectly well but in a different way.
MarioNovak wrote:But, reduced/less complex state of the system is conditio sine qua non for the idea of evolution. Hence, we can conclude that human mental constructs in the form of ideas, ad hoc hypotheses or theories postulating that reproductive system is result of the accumulation of small heritable changes within populations over time are in contradiction with science, and therefore false.
Straightforwardly false at both an empirical and conceptual level. We can directly observe extant organisms at various levels of complexity with many of the key components
we require for sexual reproduction, lacking in the pertinent species. Many examples have been given already in this thread. These putative observed "stages" in the evolution of sexual reproduction correlate well with the genetic and morphologically derived phylogenetic history of life (meaning we have very strong evidence that they are the result of an evolutionary process). Furthermore, we have strong conceptual reasons for rejecting your argument, in that your foundational portrayal of evolutionary history and the process itself is erroneous, because you have not considered that changes to the extant reproductive systems and strategies were back then accompanied by fundamental changes to organismal physiology and behavior.
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