Red Blood Cells

[Turtle]

this is not a misunderstanding by hydrogen-bond of what science has taught us, this is intentional obfuscation meant to discredit science and promote religious beliefs. while many of you may be content to let it slide with a wink & a nod, i am not of that frame of mind. not a snow ball's chance in hell.

What are the options other than ban HB from the forum ?

 

none. click the Report button in the lower left corner of his posts & tell the staff exactly what you think.

[Turtle]

let me preface by saying that if you - dear tender readers all - don't approve of my posts here, then do me the courtesy of reporting them as well. i welcome a frank discussion with the powers that be.

 

let's revisit the opening post:

 

...

Here is the scenario. Hypothetically, say the red blood cells had nuclei/DNA and were able to replicate within the blood. Could this account for the large size of dinosaurs?

 

The logic is, if the red blood cells could divide in the blood, ...

 

off the bat, because this is a "hypothetical scenario" it belongs in our silly claims section, not biology. :naughty:

 

h-bond would have us believe he is adept at science through using terms like "entropy" or "nuclei/DNA" or "replicate", etcetera, however while it might seem a bright idea from a 6 year old that a big animal is big because it has more blood, it is not a mistake someone with even a modicum of study in biology - or logic for that matter - would make. (never mind that a bright 6 year old knows that blue whales alive today are bigger than any dinosaur.)

 

again, the fact is this is not a mistake by h-bond, it is an intentional deceptive obfusacatory stylistic device meant to denegrate science as an arbitrary endeavor and promote religious beliefs - creationism etcetera - as the equal or superior endeavor to science. this being a science site, the material does not belong here at all in my opinion.

 

then again we have a complete lack of references via links or other sources from h-bond to support any of his mouthings despite direct requests and despite the fact that our rules and very purpose statement virtually require such reference. this is trolling plain & simple regardless of the motivation.

 

i could go on - and will later if need be - but i have only so much posting in me & i'm spent.

[Turtle]

in for a penny, in for a pound.

 

so where you may be asking is all this god reference in h-bonds posts that the big bad turtle keeps yammering on about. well, obfuscated of course. while h-bond fancies himself a more clever writer, i fancy myself a most clever reader. first, this isn't just any old religious business, it is christian business that we all know as creationism. allow me to reference that.

 

http://en.wikipedia.org/wiki/Creationism

Creationism is the religious belief[1] that humanity, life, the Earth, and the universe are the creation of a supernatural being. However, the term is more commonly used to refer to religiously motivated rejection of certain biological processes, in particular much of evolution, as an explanation accounting for the history, diversity, and complexity of life on earth.[2] As science developed from the 18th century onwards, various views developed which aimed to reconcile science with the Genesis creation narrative.[3] At this time those holding that species had been separately created were generally called "advocates of creation" but they were occasionally called "creationists" in private correspondence between Charles Darwin and his friends. As the creation–evolution controversy developed, the term "anti-evolutionists" became more common, then in 1929 in the United States the term "creationism" first became specifically associated with Christian fundamentalist opposition to human evolution and belief in a young Earth, though its usage was contested by other groups who believed in various concepts of creation.[4] ...

 

now to the devil's details.

 

... Could this account for the large size of dinosaurs? ...

 

so why dinosaurs? well, because science has them millions of years old but that doesn't fit with a literalist/creationist reading of genesis & so such folk as make such reading have to try & bumfumble a kabobbled explanation for how they, the dinosaurs, could be but a few thousand years old.

 

so, a few examples of h-bond's "clever" insertions of literalist-genesis-reading acceptable terms.

 

The idea of replicating red blood cells would add something similar to a turbo or supercharger effect, ...

 

I am looking at the energy side of the equation of life. Cells can't so anything without an energy supply. Even genetics becomes limited. ...

 

As an analogy, we add a supercharge to the car. The extra performance makes the car sort of lopsided. We may need to upgrade the suspension, transmission, etc. With the extra boost of energy to the DNA, we also the have the R&D conditions for the future of selective advantage.

 

added? cells can't do anything, but god of the pentateuch can. that god is h-bond's extra energy supply & chief grease monkey.

 

If we started from scratch, evolving an efficient lung system, versus simple red blood cell replication, the red blood cell replication is already up and running almost from the beginning. The other needs time.

 

... A simple behavior change can do the same things as millions of years of evolution. ...

 

almost from the beginning? already made? what beginning, erhm... genesis, is that again? who /what could do that? could it be, oh i don't know,... satan? (well, until his dad took away his keys for talking back :evil:) it is the big G of G changing behavior as well. fickle as the proverbial finger of fate. :lightning

 

...

I prefer to work under the assumption of logical explanations, using energy considerations, since even random is not possible unless there is energy to drive the entropy. This is not speculation but is called energy conservation.

 

All the random things which are assumed to drive evolution now have additional energy for entropy, such as cell division. ...

 

again with the energy bit. guess who? :angel: that's right; god of genesis. how conveeenient.

 

Lack of efficiency at the DNA means not all reactions will work, unless we crank up the energy input so we get a higher yield. The higher level of waste energy will be absorbed by the local water, with equilibrium on the DNA more conducive to mistakes. ...

 

ooooohhhh! the "local water" is it? energy again too!!?? oh that's right :doh: ; noah's flood that god made.

 

i conclude with some references as to why i give a good goddamn about this from a secular perspective, as we have discussed the creationist business here @ hypography ad nauseum.

 

Trolls

An Internet troll is a person who delights in sowing discord on the Internet. He (and it is usually "he") tries to start arguments and upset people. It's ALL about "Getting Attention", and negative attention is as good as positive attention to a troll.

 

Trolls see Internet communications services as convenient venues for their bizarre game. For some reason, they don't get that they are hurting real people. To them, other Internet users are not quite human but are a kind of digital abstraction. As a result, they feel no sorrow whatsoever for the pain they inflict. Indeed, the greater the suffering they cause, the greater their 'achievement' (as they see it). At the moment, the relative anonymity of the net allows trolls to flourish.

 

Trolls are utterly impervious to criticism (constructive or otherwise). You cannot negotiate with them; you cannot cause them to feel shame or compassion; you cannot reason with them. They cannot be made to feel remorse. For some reason, trolls do not feel they are bound by the rules of courtesy or social responsibility while hiding behind the anonymity of a keyboard and monitor.

...

The ultimate response to the 'free speech' argument is this: while we may have the right to say more or less whatever we want, we do not have the right to say it wherever we want. You may feel strongly about the fact that your neighbour has not mowed his lawn for two months, but you do not have the right to berate him in his own living room. Similarly, if a webmaster tells a troll that he is not welcome, the troll has no right to remain. This is particularly true on the numerous free communications services offered on the net.

 

i trust this clarifies some issues; any others will have to wait as i have made my column-inch quota.

[maikeru]

I like the idea of replicating red blood cells because of its simplicity. If we started from scratch, evolving an efficient lung system, versus simple red blood cell replication, the red blood cell replication is already up and running almost from the beginning. The other needs time.

 

In my experience, efficiency shines brighter when there is necessity. For example, during times of plentiful food what is the advantage of an efficient digestive system? A simple behavior change can do the same things as millions of years of evolution. The importance of hardware efficiency will come more into play when the food level drop. At 35% O2, what is the advantage of O2 exchange efficiency? However, when the O2 level fall, the need for efficiency shines brightly.

 

It makes no sense. Replicating blood cells would impose a substantial energy burden on the organism as well as survival liabilities such as heightened risks for dangerous blood cancers similar to leukemia, lymphoma, etc. and failing cell membranes and organelles (due to the rigors that RBCs must endure) that your proposed hypothetical RBC-replicating organism would probably be dead within the blink of an eye. Their task is simple but important, their life short but dutiful. Given these thoughts, it is better to mass produce RBCs and replace them than to replicate and repair them with said liabilities.

[HydrogenBond]

I agree that the modern strategy is the more advanced/evolved way to deal with oxygen transport. I was reading that the red blood cells in birds have nuclei, but only last about 1/2 as long as RBC where the nuclei are removed. An extrapolation to replicating RBC might mean very short life.

 

An interesting observation is the embryo produces red blood cells in the liver before it uses bone marrow. Before the embryo uses the liver, the blood of the mother or direct red blood cell infusion, at the high level of an adult, gives the embryo a running start. That is a detached source of RBC, until internal differentiation into the more regulated liver source. Then that first differentiated source changes, until the highest efficiency occurs via bone marrow.

 

I saw RBC replication like a rich mother source, beyond normal regulated internal capacity.

[Rade]

I saw RBC replication like a rich mother source, beyond normal regulated internal capacity.

I hope you now see that such replication, for the first vertebrates, would be more like a poor father, providing little, thus extinction, rather than a rich mother, providing much, thus survival.

[HydrogenBond]

Biology is empirical, so the only way to know for sure what would happen if RBC could replicate would be to run experiments. Biology is not a science that is grounded on logical inference, so anything we might infer would not compute without hard data.

 

Human RBC havde no nuclei. However, there are examples were RBC do have nuclei, but can't reproduce. If we continue the extrapolation, we will get RBC with nuclei that on occation can replicate. Next, RBC replicate more and more often. But again logical inference is not the foundation of biology, so experiments would need to be done to prove it one way or the other.

 

The movement into the modern RBC, without nuclei allows better O2 carrying properties. If we extrapolate backwards, each stage would mean less O2 efficiency, which would only work if O2 levels were higher, which they were. Currently we have 22% O2 but data says the earth was abpout 35% back in the day. So about 55-60% efficiency would work fine.

[HydrogenBond]

Red bloods cells without nuclei are flexible, allowing them to travel in tight places. This can support smaller blood vessels. When RBC have nuclei they are stiffer. Relative to replicating RBC, these would be stiffer and might mot be able to travel within tiny blood vessels. The circulatory system would need to be bulkier and might not offer full modern support for body systems that need a more delicate circulation. I can see the skin being insensitive, etc.

 

In modern human RBC, there is an interesting paradox. These metabolize in an aerobic way from glucose to lactic acid, yet they have a rich source of O2 on their membrane surface. This suggests that hemoglobin sort of acts as an oxygen barrier for the inside of the cell. For RBC to replicate, they would benefit by more O2, and therefore by less of a barrier. This would amount to a lower concentration of hemoglobin in the cell membrane. As these RBC get more and more efficient at making and retaining hemoglobin, replication problems will appear. If we used selective advantage arguments, the most advanced would stop replicating, while the inefficient would replicating longer.

 

An interesting observation is that although human RBC last 3-4 months, the RBC in some turtles can last over a year. This is explained via the slower metabolism of the turtle. If animals had a distribution of non-replicating and replicating RBC, while also having a slow metabolism, the nonreplicating would accumulate since they could last longer. This would start to shift equilibrium more toward nonreplicating resulting in this system wide differentiation.

 

All still needs experiments but those are some of my inferences.

[Rade]

But again logical inference is not the foundation of biology, so experiments would need to be done to prove it one way or the other.

Well, biologists do use logic inference to help with explanations where experiments are not possible, such as to help explain the sequence of fossils in rock formations. One cannot conduct experiments to understand the sequence, one must use inference in combination with facts, hypotheses, and laws of nature to help explain. So, logical inference is a very useful tool in the explanation toolbox of the biologist.

 

The movement into the modern RBC' date=' without nuclei allows better O2 carrying properties. If we extrapolate backwards, each stage would mean less O2 efficiency, which would only work if O2 levels were higher, which they were. Currently we have 22% O2 but data says the earth was about 35% back in the day. So about 55-60% efficiency would work fine.[/quote']HB, your hypothesis does not work. Consider why the RBC loses efficiency, it is because there are fewer hemoglobin molecules per unit area, because space is being taken up by the nucleus. So, having more O2 in the environment does not help, the extra O2 does not have more hemoglobin to attach to. The reason 55-60% RBC efficiency would work for early vertebrates is because they were "cold blooded" and do not require more than 55-60% based on energy needs. Also, as discussed before, the process of replicating DNA would take energy that the early vertebrate RBC does not have. The vertebrate RBC do not have a mitochondria, hence the amount of ATP they can produce is limited to anaerobic type respiration.

[Turtle]

...An interesting observation is that although human RBC last 3-4 months, the RBC in some turtles can last over a year. This is explained via the slower metabolism of the turtle. If animals had a distribution of non-replicating and replicating RBC, while also having a slow metabolism, the nonreplicating would accumulate since they could last longer. This would start to shift equilibrium more toward nonreplicating resulting in this system wide differentiation.

 

All still needs experiments but those are some of my inferences.

 

infer this.

 

Hypography Rules

Be yourself. But please respect these ground rules:

 

■In general, back up your claims by using links or references.

 

■If you make strange claims, please provide proof or at least backup of some kind. If you fail to do so, or the backup you provide is not deemed adequate, the moderators may move your post to the Strange Claims forum. ...

 

The Biology of Sea Turtles

 

10.4.4 Blood Oxygen Transport

 

For sea turtles (and also marine mammals) the respiratory properties of blood may depend upon whether oxygen is stored primarily in the tissues or in the lung during the dive, as the problems of blood oxygen transport are quite different in either case. ^{3.67.70.72.73} For example, marine mammals and the leatherback sea turtle that store oxygen in the blood often have comparitively high hematocritis, which increase the blood oxygen-carrying capacites. (Table 10.2) The deep-diving leatherback, for example, has the greatest hematocritic values of any reptile (32% to 38%). ²⁷ ...

 

[HydrogenBond]

The one thing that always struck me, relative to human RBC, was they did not need a nucleus/DNA to survive. It is true, that the life expectancy of RBC is not very high. However, the extruded daughter cell, which is mostly DNA and nucleus, is dead in the water.

 

Based on that, the RBC cell body is more alive than its DNA. The question becomes who needs who, more? If see the correspondence of the DNA and cell body as the DNA being analogous to the hard drive of a computer, with the cell body the rest of the computer. The computer can still run off the mother board if we remove the hard drive, like RBC do. The hard drive is inert when taken out of the computer. But if the hard drive is added, it can expand the capability of the computer.

 

Say we were to add the genetic hard drive back to the RBC body, going back into time. What would happen is we would add the potential for more capability. This may not be advantageous to O2 transfer, since other DNA programs might run which is not in the best interest of high oxygen carrying ability. The cell is more self interests than team spirit. Replicating RBC would not look like modern RBC, but would have other capabilities which may not be as conducive to oxygen-CO2 transfer specialization, but nevertheless allow other internal environmental advantages.

 

The direction of evolution moved the DNA of RBC in the direction of narrowing specialization, until it was extruded. It is not the DNA narrowing itself, but rather input via the cell body, narrowing the DNA until it becomes useless.

[Turtle]

The one thing that always struck me, relative to human RBC, was they did not need a nucleus/DNA to survive. It is true, that the life expectancy of RBC is not very high. However, the extruded daughter cell, which is mostly DNA and nucleus, is dead in the water.

 

Based on that, the RBC cell body is more alive than its DNA. The question becomes who needs who, more? If see the correspondence of the DNA and cell body as the DNA being analogous to the hard drive of a computer, with the cell body the rest of the computer. The computer can still run off the mother board if we remove the hard drive, like RBC do. The hard drive is inert when taken out of the computer. But if the hard drive is added, it can expand the capability of the computer.

 

Say we were to add the genetic hard drive back to the RBC body, going back into time. What would happen is we would add the potential for more capability. This may not be advantageous to O2 transfer, since other DNA programs might run which is not in the best interest of high oxygen carrying ability. The cell is more self interests than team spirit. Replicating RBC would not look like modern RBC, but would have other capabilities which may not be as conducive to oxygen-CO2 transfer specialization, but nevertheless allow other internal environmental advantages.

 

The direction of evolution moved the DNA of RBC in the direction of narrowing specialization, until it was extruded. It is not the DNA narrowing itself, but rather input via the cell body, narrowing the DNA until it becomes useless.

 

pure unadulterated bullshit! either provide supporting links/sources or get this trash off our board.

[Rade]

Say we were to add the genetic hard drive back to the RBC body, going back into time. What would happen is we would add the potential for more capability...allow other internal environmental advantages.

No, this is not what would have happened, there are no other internal advantages to have RBC reproduce in early vertebrates. You need to bring forth facts.

 

The direction of evolution moved the DNA of RBC in the direction of narrowing specialization' date=' until it was extruded. It is not the DNA narrowing itself, but rather input via the cell body, narrowing the DNA until it becomes useless.[/quote']Suppose a very early vertebrate that evolved a mutation to DNA that allowed RBC with a nucleus to replicate. What would be the direction of evolution ? All individuals that carried this DNA mutation would not be able to carry enough O2 to body cells. Without enough energy the animal would die, and all those that carried this mutated DNA gene would die, and the species would become extinct. Energy is of such vital importance, there are no secondary advantages to such a mutation.

 

Over time, as vertebrates evolved into mammals that required more energy, a second type of mutation would have been selected, a mutation that resulted in no development of a nucleus in those stem cells that would form specialized RBC to carry O2. Notice how the ultimate cause involved mutations to DNA in both cases, the first to select against species that allowed DNA to replicate within RBC, the second a mutation to DNA of the stem cells. So, it both cases, it was a case of the DNA narrowing itself as you say, via mutations.

 

HB, I do agree with Turtle that it is time for you to post to another thread topic, you have nothing to add to the understanding of why RBC do not reproduce in vertebrates.

[HydrogenBond]

The point I was making is the RBC body can survive without a nucleus. However, the nucleus is dead in the water. From that observation, I would infer that a cell body is more alive than its nucleus, or else a separated nucleus would not only live, showing all signs of life, but would become a self replicator, rebuilding another cell body. Has this ever been observed?

 

I understand tradition has the DNA as the center piece of life, but RBC don't go along with the program. RBC currently develop from stem cells within the bone marrow. The bone marrow is the external environment, which tweaks the stem cell bodies, which tweaks the DNA, eventually ejecting the hard drive. The DNA is used and discarded, since it is no longer needed.

 

Hypothetically, say a RBC could replicate. I am not saying it does, but follow the logic. The hierarchy begins within the external environment surrounding these autonomous RBC. This potential goes into their cell bodies, to their DNA. The blood supply, which would contain these hypothetical replicating RBC, is part of the external environment that will seen by the rest of the cells of the body, due to the blood circulation. This variable external environment, due to the hypothetical RBC cell cycles, will externally impact all the cell bodies, which will tweak their DNA.

 

These tweaks change the external potential that is in contact with the blood, due to cell interfaces. This alters the external potential seen by the RBC. We have two dependent, yet competing external potentials, with the DNA at the bottom of the potential tree. The final result was RBC replication stopping, but only after other differentiations.

 

Female gamete cells do something similar to modern RBC, in that they extrude half the nucleus. Based on the above logic, an external environmental potential, tweaks these cell bodies, which tweaks their DNA. After the DNA is used, the cell body ejects part of the DNA like a bad hard drive. We now need another external potential; sperm cell.

 

The external environment, for forming gamete cells, is more than just nurse cells, since even the nurse cells will have their own external environments. If we keep moving up the external environmental hierarchy, we eventually define the external environment in the context of global body systems. In the hypothetical case of replicating RBC, this unique situation would be part of a major global potential, but not the entire potential. They would have an indirect impact even on gamete cells that will reflect this potential.

 

Again if one assumes the DNA is leading, the logic is different, since random changes, drift and selective advantage will apply. One would assume that replicating RBC can only occur in a random mutation way, and since it offers no advantage in the context of modern cells, that means it would have not persisted or had any impact. The debate is fundamentally based on which premise is correct, DNA leadership or DNA dependency

[Rade]

The point I was making is the RBC body can survive without a nucleus. However, the nucleus is dead in the water.

Well, the RBC does not survive very long, so, it is just as dead in the water without the nucleus as the nucleus is without the cell. To have an activity called survival, both the cell and a nucleus are required, not one or the other. This false claim you make here, follows all the way to your last comment, where you conclude with a false premise that life places DNA either before or after the potential of the cell.

 

From that observation' date=' I would infer that a cell body is more alive than its nucleus [/quote']Well, seeing how your observation is incorrect, can you see how this conclusion is silly ? The cell is not more alive if it has no ability to survive and reproduce over time because it has no nucleus. Your argument below follows from this false understanding you have of the relationship of the cell to the nucleus, how they interact.

 

or else a separated nucleus would not only live' date=' showing all signs of life, but would become a self replicator, rebuilding another cell body. Has this ever been observed?[/quote']No, this is silly. Why would you expect a nucleus separated from a cell to show all signs of life ? You miss a very important point, life by definition requires BOTH a cell that has a boundary (thus an inside and outside) plus some way to reproduce (which is where the RNA and DNA come into place). Long before there was a nucleus, there were isolated RNA (first) and DNA (latter) molecules within the early single cell forms of life. So, can you see why it is silly for you to suggest that an isolated RNA or DNA molecule separated from a cell environment can show signs of life floating in the ocean ?

 

I understand tradition has the DNA as the center piece of life' date=' but RBC don't go along with the program.[/quote']No, the RBC is a specialized cell that is formed from what you can think of as a RBC stem cell (mostly within bone marrow) and that stem cell reproduces to form the RBC using DNA. Therefore, the RBC most surely does go along with the DNA program.

 

RBC currently develop from stem cells within the bone marrow. The bone marrow is the external environment' date=' which tweaks the stem cell bodies [/quote']Bone marrow does not tweak stem cells. Look in the dictionary, to tweak something means to seize and pull with a sudden jerk and usually a twist. HB, this is a biology thread, you need to use biological terms to explain what you are trying to get across.

 

...which tweaks the DNA' date=' eventually ejecting the hard drive.[/quote']Again, the RBC does not tweak (seize and pull) the DNA, and then push it out of the cell, the way the bouncer pulls the drunk out of the bar. HB, do you not understand that the DNA function was lost from higher vertebrates in stages over time due to the actions of select genes being repressed, there was no other type of "external potential" that you keep bringing up.

 

The DNA is used and discarded' date=' since it is no longer needed.[/quote']The DNA genetic function was repressed, NOT BECAUSE IT WAS NO LONGER NEEDED, but because those RBC that did not have DNA taking up space could pact more hemoglobin per unit area and thus carry more O2, a trait that was adaptive as vertebrates evolved into early mammals.

 

Hypothetically' date=' say a RBC could replicate. I am not saying it does, but follow the logic.[/quote']OK, in fact, I agree it is possible that some evolutionary lines of very early vertebrates (as they transitioned from invertebrates) may have had RBC that could replicate. OK, what would we predict ?

 

The hierarchy begins within the external environment surrounding these autonomous RBC. This potential goes into their cell bodies' date=' to their DNA.[/quote']By potential I assume you mean the O2 concentration potential outside the RBC ? OK, yes, by diffusion O2 would enter into the RBC. But, no, this potential does not "go to their DNA" ! This is where your argument fails, there is no external potential going to the DNA. The O2 attaches to HEMOGLOBIN molecule, a different type of molecule that DNA. And, logic demands that if this reproducing RBC has a nucleus taking up space, then less O2 can attach to hemoglobin than if the cell did not have DNA.

 

The blood supply' date=' which would contain these hypothetical replicating RBC, is part of the external environment that will seen by the rest of the cells of the body, due to the blood circulation.[/quote']Yes, the blood supply is external to the RBC, you have this correct. And, if by "seen" you mean that the blood and RBC are circulated to all the other types of cells (such as muscle, skin, etc.), you are correct again.

 

This variable external environment' date=' due to the hypothetical RBC cell cycles, will externally impact all the cell bodies, which will tweak their DNA.[/quote']No, no, no....the blood and the RBC that travel to the muscle cells do not "tweak" (pull and twist) the DNA within the skin cells. What happens is that the RBC release the O2 and it travels into the muscle cells and enters the MITOCHONDRIA because the muscle cells need the O2 to help create energy in the form of ATP molecules. The ATP is made within the mitochondria, not the DNA, so if there is any tweaking going on, it is going on within the mitochondria (but of course there is no tweaking at all, again, this is a biology thread, you must learn to use proper biological terms).

 

These tweaks change the external potential that is in contact with the blood' date=' due to cell interfaces.[/quote']No, it is not called "tweak", the process is called O2 diffusion across the cell membranes (from high concentration within RBC to low concentration within muscle cells).

 

This alters the external potential seen by the RBC. We have two dependent' date=' yet competing external potentials, with the DNA at the bottom of the potential tree. The final result was RBC replication stopping, but only after other differentiations.[/quote']No, the DNA is not at the bottom of any type of tweaking potential tree. The RBC replication stopped because those species with a gene mutation that stopped DNA replication would have a survival advantage because they could have more O2 diffuse into muscle cells and thus form more ATP energy as vertebrates evolved into mammals.

 

Female gamete cells do something similar to modern RBC' date=' in that they extrude half the nucleus. Based on the above logic...[/quote']There is nothing logical, your claim is false. The stem cells that form gametes do not "do" anything similar to stem cells that form RBC in mammals. Gametes carry 1/2 of the species chromosomes because one from each sex must unite to form a new individual. RBC lose 100% of their chromosomes (in mammals) because they can more efficiently transport O2. One outcome relates to reproduction of a new individual, the other relates to keeping the individual alive so that it can reproduce.

 

...an external environmental potential' date=' tweaks these cell bodies, which tweaks their DNA. After the DNA is used, the cell body ejects part of the DNA like a bad hard drive. We now need another external potential; sperm cell.[/quote']Where your hypothesis fails is that an external environmental potential that tweaks gametes does not exist, the only global potential of the body systems concerning gametes (egg cells and sprem cells) is the fact that each individual of a sexual species must survive and reproduce so that the species can survive. There are many advantages to sexual reproduction over asexual reproduction dealing with concept of information variety.

 

Again if one assumes the DNA is leading' date=' the logic is different, since random changes, drift and selective advantage will apply. One would assume that replicating RBC can only occur in a random mutation way, and since it offers no advantage in the context of modern cells, that means it would have not persisted or had any impact.[/quote']But, evolution theory does not assume that DNA is leading or not leading, the cell needs DNA, the DNA needs the cell, neither is primary over the other, and here we see exactly why your hypothesis is false, because it is based on the following false either-or conclusion you make to end your post

 

The debate is fundamentally based on which premise is correct' date=' DNA leadership or DNA dependency [/quote']No, there is no debate, you demand an either-or situation where none exists. DNA both depends on the protection given to it by the boundary of the cell, and provides the genetic information required to help keep that cell boundary alive so that it can continue to exist (reproduce) over time.

[CraigD]

Lamarck, computer analogies, and flouwen :)

Based on that, the RBC cell body is more alive than its DNA. The question becomes who needs who, more?

Rade answered this question, convincingly IMHO, with the conclusion that the question is not useful, because it assumes inaccurate analogies about cells and DNA. I’ll add only that the heart of the analogy’s problem seems to me to be that DNA and cells aren’t people, so referring to them with “who”, and as having “needs”, is bound to be problematical.

 

If see the correspondence of the DNA and cell body as the DNA being analogous to the hard drive of a computer, with the cell body the rest of the computer. The computer can still run off the mother board if we remove the hard drive, like RBC do. The hard drive is inert when taken out of the computer. But if the hard drive is added, it can expand the capability of the computer.

I think this analogy hints at Lamarckism.

 

Intuitively, computer hard drives are useful not only because they contain data that “tell the computer hardware what to do”, but because they can “learn” by storing new data. Despite extensive searching for exceptions, however, somatic DNA can’t do this. More accurately, DNA is analogous to read-only-memory (ROM).

 

The idea that genes (which Lamarck didn’t, but we do know, are encoded in DNA molecules) “learn” from their organism’s experience, passing this information to their organisms children, is Lamarckism. It was a reasonable theory when introduced ca 1800, but subsequent understanding of the actual mechanics of DNA have shown it to simply be wrong – though a few hold hope that it may, in rare cases, occur, and the search for such rare occurrence continue on the fringe of biochemistry.

 

This thread has seen a vigorous discussion of genetics and physiology, but I sense that it’s drifted from HBond’s original “what if red blood cells could reproduce in the bloodstream” speculation. Even this, I suspect, is too specific – I think what’s at the heart of this speculation is the very fundamental biological question “why do all big organism have so much cell specialization?”

 

Though a fertile line of speculation in SF literature (the late Robert Forward’s flouwen are my favorite example of a big, intelligent animal made completely of non-specialized cells), the rule in real evolutionary biology appears to be increased cell specialization equals increased evolutionary success. Whether this must always be the case – that is, if Forward’s flouwen are pure SF fancy, or could, given the right environmental condition, actually exist – has long been a fascinating question for me.

[Rade]

Lamarck, computer analogies, and flouwen :)

 

I think this analogy hints at Lamarckism.

Thank you for the post. I agree that the "tweak" concept of HB most likely is a type of evolutionary Lamarckism. There is also the possibility that HB is talking about epigenetic type interactions, which are well studied by biologists--see this link:

 

http://en.wikipedia.org/wiki/Epigenetics

 

That factors within the environment of a cell can effect the RNA and DNA is well established and a hot topic for current research. It is the mechanism of how the environmental factors effect the RNA and DNA that is controversial. So, does the cell environment modify the RNA and DNA nucleotide sequence, which would result in a type of mutation, or do epigenetic factors cause certain genes along the RNA and/or DNA (or gene complexes) to turn off or on at different times of cell life cycle--and do we call the second action a mutation or not ? Whatever the mechanism, evolutionary biologists allow for epigenetic potential to be inside the theory. That is, epigenetic processes do not mean evolutionary theory is incorrect, they represent another tool in the toolbox to help explain the reproduction of genotypes over time. Where the process is non-random, the mechanism is called natural selection, but random (such as DNA recombination during meiosis) and neutral changes to genotypes are also possible.

 

From my read, HB would want the level of O2 in the blood in large vertebrates to serve to "tweak" the RBC nucleus in such a way that the DNA cannot replicate. If high levels of O2 in the cell environment can result in such epigenetic response in DNA, it is a hypothesis that could be tested experimentally. I will grant HB this type of "tweak", but he needs to use biological terms, not "tweak". I am not aware of any such epigenetic studies relating O2 and DNA.

 

This thread has seen a vigorous discussion of genetics and physiology' date=' but I sense that it’s drifted from HBond’s original “what if red blood cells could reproduce in the bloodstream” speculation. Even this, I suspect, is too specific – I think what’s at the heart of this speculation is the very fundamental biological question “why do all big organism have so much cell specialization?”[/quote']Not sure what you mean by "big" ? The hydra has lots of cell specialization but I would not call it big.

 

Perhaps another line of thought, along the thinking of Robert Forward SF fiction that you mention. Why is there an increase in cell specialization along both lines of ontology and phylogeny ? What is the selective advantage ? Such specialization of function is found in the most simple forms of life, those with a single cell. The single cell bacteria has molecules that group together to form special functions (bi-lipid layer of membrane, RNA, DNA, etc.). Consider the Ameoba, much molecular specialization within a single cell much more complex than the bacteria. So, even within the line of single celled organisms, which evolutionary theory has lasting many millions of years, there is a trend toward increased molecular specialization. The process of mitosis changed the game of life, now two, 4, 8, 16, 32, etc. cells combined could continue the specialization process. An interesting topic, what caused the first single cell to undergo mitosis, to divide ? Was it epigenetic response or some random mutation ?

 

Though a fertile line of speculation in SF literature (the late Robert Forward’s flouwen are my favorite example of a big' date=' intelligent animal made completely of non-specialized cells), the rule in real evolutionary biology appears to be increased cell specialization equals increased evolutionary success. Whether this [i']must[/i] always be the case – that is, if Forward’s flouwen are pure SF fancy, or could, given the right environmental condition, actually exist – has long been a fascinating question for me.

I think the flouwen of Forward would require a different type of physics, matter composed of non-specialized fundamental particles. So, no electrons and protons, up and down quarks, matter and antimatter, etc. One basic fundamental particle with potential for all force functions.

 

Suppose a big animal made only of generalized stem cells. How could it move out of this state except to specialize ? So, suppose an environmental factor that adds some potential to cause the mass of stem cells to move. So, a select group of such stem cells respond to form a potential for movement, but wait, these cells now become specialized. So, I cannot see how the flouwen of Forward could become big and intelligent yet remain pure stem cells ? I mean, to be intelligent and big are two types of specialization that certain cells within the flouwen must have. In a generalized Forward world, I would also expect small and intelligent forms of life, as well as small and big and not so bright. Maybe the big intelligent forms use the others for food energy ? Not sure if Forward has such diversity of life forms present on his SF world, looks like I have some good SF to read.