Speculative biology question

1. Yes, and all it would really need is a significant percentage of persistent fetal hemoglobin, which normally drops after birth.

2. Yes, and the easiest solution is to do what the dolphins do, only sleep half of the brain at any given time.

GeorgeK said:

do what the dolphins do, only sleep half of the brain at any given time.

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Nothing new here. I know all sorts of people who sleep with half of the brain all the time.

caw

1) Dogs only need about 50% of their lungs. While they won't be winning marathons, you might look into how much lung space you can lose in humans without requiring major compensations. A minor compensation would just be producing more blood cells, giving you a high hematocrit.

Keep in mind that lungs that don't expand will change over time, so if they suddenly have space to expand, they won't.

Consider nano-tech. Because it doesn't yet exist, is mainly theory, you can most likely get away with having nano machines do whatever you want them to. Think: the gills on Kevin Costner in the 1995 film "Water World." As depicted, little pink fringe things behind his ears, woefully inadequate for oxygen-to-blood transfer in a being as large as a human, especially in salt water. AND they had to work coincidentally with his lungs when he was on the surface. Improbable at best--but it made the story work (sorta).

Nano machines might be able to convert the skin to an oxygen absorber, they might be rampant in the blood to carry and/or store oxygen for use during high consumption periods (exercise, running from the bad guy), etc. And you might consider some implanted artificial organ that could store and meter oxygen into the blood. It could be smaller than lungs, not require the diaphragm to work, etc., giving you room for whatever else you need in the guy.


As far as your computer-brain interface thing, William Gibson explored something similar. Allowing your character to rest while still active on the "net," as it were, is a great idea. Current thought is that humans cannot truly multi-task; they can only do one thing at a time. What appears to be multi-tasking is really multi-threading, where one thing is done, then the other, then the first, then the other, etc, very rapidly. With a computer link in the guy's head, that becomes very efficient, and all you need is a little handwavium to explain how it allows the brain to rest along with his body during this period of apparent total conciousness.

Neat ideas.

For the lung modification, specially tailored symbiotic bacteria will do the job, and are more of a possibility right now than nano-machines. Plus, the behavior of bacteria has been established. You can research that and put more realistic detail into your story than you'd get with a technology whose parameters you'd be creating yourself.

As for the interface...Read the case histories of Oliver Sachs. Sachs is a neurologist who has popularized his work with books like The Man Who Mistook His Wife for a Hat. One of the themes that emerges is that the brain is not a unitary thing - it's composed of dozens of different centers with different responsibilities (balance, color perception, short-term memory, long-term memory, etc.) so you could make a case for the mind remaining awake while the body was asleep.

Actually, increased carrying capacity for oxygen alone won't cut it, what's the bottleneck long-term, i.e. after the reserves in the blood and the spleen are exhausted, is the gas exchange capacity of the lungs. While increasing the oxygen capacity of can help with that, but the easier fix would be to have the lungs changed in a way that increases the gas exchange taking place. For example having lungs with even higher internal surface area than normal would do that.
When the fix is supposed to happen by changing the blood, having higher oxygen capacity alone won't do it, what's necessary is to have blood with higher oxygen affinity, which will exchange O² and CO² in the lungs quicker than normal (Haemoglobin-F does that). Higher affinity can coincide with higher bonding capacity, but doesn't have to (Haemoglobin-F doesn't).
Since GeorgeK mentioned Haemoglobin in foeti, one side-effect of having blood with higher oxygen affinity would be the inability to become pregnant. The foetus wouldn't be able to extract oxygen from the mothers blood (which is what foeti need the higher oxygen affinity for).

On 2), if the consciousness can run on hardware different than the original brain, i see no reason why it wouldn't be able to be kept running while the body is sleeping. Theoretically, that's even possible without a computer. The body needs rest more so than the brain needs sleep, you could theoretically practice to survive with a few hours of REM sleep each day, so long as you add some more hours of no physical activity. Only theoretically though, i'm not aware of anyone trying it for long enough to say for sure, so far. Let alone a study with a representative number of people. Since the potential side effects of messing with sleep are ... unpleasant, i don't think anyone'll be willing to try soon either. Though in theory, it could work.

Lhun said:

Since GeorgeK mentioned Haemoglobin in foeti, one side-effect of having blood with higher oxygen affinity would be the inability to become pregnant. The foetus wouldn't be able to extract oxygen from the mothers blood (which is what foeti need the higher oxygen affinity for).
.

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That's not quite true, as evidenced by Sickle Cell Disease (not to be confused with Sickle Cell Trait) patients. They have a significant persistence of Hgb-F and can get pregnant (Although to be fair, that assumes that they live long enough for that to happen, and those who do generally will miscarry). There are a variety of thallasemias that will have similar effects with variant hemoglobins which are more survivable. The point was that it would not be a scientific stretch to have a variant hemoglobin that allows function in lower oxygen environments. Sickle Cell Trait and Disease are simply the best known in existence.

veinglory said:

Would there be any other physical implications if we assume some increase in lung reticulation and alveolar structure and hemoglobian that has higher oxygen affinity?

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Mainly the problem would be when you shift the binding capacity to accept CO2 as a source of O2, then you are also shifting the binding capacity to more easily accept Carbon Monoxide as well. In a lot of those hemoglobin diseases the problem there is that often CO will bind irreversibly, so that although the person could probably last longer in a CO2 environment, typically those environments will be also high in CO, and so recovery from entering those environments will be slow. (Typically a red cell lasts 3 months) The upshot is you have to be alive to complain, so they'd be alive, but complaining for a few weeks. They'd probably need higher release of erythropoietin (a hormone that tells the marrow to make hemoglobin). If this is a chronic condition, they'd also be predisposed to clots because of secondary polycythemia. Therapeutic phlebotomy wouldn't work because the environment would then kill them, (again, assuming constant exposure and not just brief jaunts).

They could deal with the clot issue by taking anticoagulants which have their own problems.

GeorgeK said:

That's not quite true, as evidenced by Sickle Cell Disease (not to be confused with Sickle Cell Trait) patients. They have a significant persistence of Hgb-F and can get pregnant (Although to be fair, that assumes that they live long enough for that to happen, and those who do generally will miscarry). There are a variety of thallasemias that will have similar effects with variant hemoglobins which are more survivable. The point was that it would not be a scientific stretch to have a variant hemoglobin that allows function in lower oxygen environments. Sickle Cell Trait and Disease are simply the best known in existence.

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Yes, "cannot get pregnant" was probably too definitive a statement. Variant haemoglobin would of course be perfectly possible for a human to have, and pregnancy as such could happen, but if the variant haemoglobin has higher affinity for oxygen, it will become a problem in pregnancy the bigger the foetus gets, since the oxygen exchange between foetus and mother doesn't work properly. Afaik, Sickle Cell Disease is not caused by the foetal haemoglobin variant, but a different one.

Lhun said:

Yes, "cannot get pregnant" was probably too definitive a statement. Variant haemoglobin would of course be perfectly possible for a human to have, and pregnancy as such could happen, but if the variant haemoglobin has higher affinity for oxygen, it will become a problem in pregnancy the bigger the foetus gets, since the oxygen exchange between foetus and mother doesn't work properly.

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Presumably these new healthy mutants would also have a variant of Hgb-F or something else to deal with it (maybe newly pregnant women retreat to a more oxygenated environment?). Things that are unsurvivable, are, well, unsurvivable. I guess we'd need more information from Veinglory about the environment to extrapolate more things, unless she's happy with the ideas so far?

Lhun said:

Afaik, Sickle Cell Disease is not caused by the foetal haemoglobin variant, but a different one.

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I never said that it was, or if I did, it was a mistake due to either over or undermedication. Persistence of Hgb-F is the body's attempt to deal with the mutated adult Hgb

Also I helped try to take care of a few sickle cell patients during med school. I say try, because other than giving them transfusions, supplemental oxygen and pain medications, at the time there wasn't much else to do. Those poor people lead a miserable existence with parts of their bodies autoamputating all the time. It was frightening to watch.

GeorgeK said:

Presumably these new healthy mutants would also have a variant of Hgb-F or something else to deal with it (maybe newly pregnant women retreat to a more oxygenated environment?).

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Well, if it's a mutation among a breeding population there obviously needs to be some away around the problem. Pregnant women taking care to always have highly oxygenated blood could work, though this would of course mean that any kind of strenuous activity would be extra-forbidden during pregnancy. But basically it could work, gas exchange is the result of a stochastic process, so the relative affinity will, ideally, determine the ratio of absorbed oxygen in the two media, though the closer the two affinities are, the longer it takes to reach an equilibrium. If foetal and maternal blood have the same affinity, you'd get a lower rate of oxygen exchange, so to compensate, higher oxygen could work, as well as an improved exchange mechanism (just as better lungs would work for the reduced volume problem).
I'm not sure how well increased oxygen content could work in practice, iirc blood is usually pretty saturated anway, though chemically it should work.

Our bodies can regulate hemoglobin's affinity for oxygen. This is particularly important going from low elevation (higher concentration of O2) to high elevation (lower concentration of O2). I suggest googling hemoglobin and elevation changes. I can't remember exactly how that works off the top of my head.

I do know that it involves a molecule called 2,3-bisphoshpoglycerate (BPG) which binds to hemoglobin and lowers its affinity to oxygen. I believe that the difference in fetal hemoglobin and adult is that fetal hemoglobin has a lower affinity to BPG (which gives the fetal hemoglobin a higher affinity to O2). Anyway, my point is that the MC could have normal hemoglobin just lower levels of BPG.

It also might be worth looking into Crocodile hemoglobin. I remember in biochemistry learning there was some difference in crocodile hemoglobin versus human which is why crocodiles can stay under water for so long. I can't remember what the difference is. It could just have to do with BPG levels as well, but it might be worth looking into.

Maybe look at bird lungs???

I have nothing else to add.

I'm a physician, not a veterinarian. I don't know enough about crocodilian Hgb to say how it is different, but I'm sure that it is not the same as human. A big part of why they can stay underwater so long though is that they can lower their metabolic rate to such low levels that they don't need as much oxygen except for their sudden surprise attacks. I imagine that that state is much like voluntary hibernation, but to be fair, that is a guess.