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By "biological brain in a box" AKA Brain in a vat I mean a robot which holds a physiologically normal human brain, and produces identical input / output as would be produced by a healthy human body (sensorial input, blood with nutrients, and output moves robot joints).

Suppose that the technology is very reliable and that the holder machine never breaks, and that the brains are not genetically altered from that of modern human beings.

I use the word biological to differentiate from a silicon simulation of brain activity.

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    $\begingroup$ It will significantly extend the demented life expectancy, until a vessel in the brain ruptures. $\endgroup$ – Peter - Reinstate Monica Jun 27 '16 at 20:23
  • $\begingroup$ @PeterA.Schneider put that comment in an answer and get rep. $\endgroup$ – Ciro Santilli 新疆改造中心法轮功六四事件 Jun 28 '16 at 10:31
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    $\begingroup$ Saying 'the technology is really reliable' seems somewhat hand-wavy. Real materials undergo fatigue and are subject to environmental degredation and are generally (in those senses and up to a logical threshold) less reliable than self-healing biological ones. $\endgroup$ – Jared Smith Jun 28 '16 at 15:19
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    $\begingroup$ @JaredSmith I hadn't thought much about that, but I suppose that the problem would be greatly offset by the fact that an old robot body could be easily changed for a new one. $\endgroup$ – Ciro Santilli 新疆改造中心法轮功六四事件 Jun 28 '16 at 15:51
  • $\begingroup$ Whatever the actual lifespan it will probably seem like a very long time to the brain in the box. Does that count? $\endgroup$ – davidbak Jun 29 '16 at 0:43

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Disclaimer: I'm no psychologist nor am I too well versed in human biology.

I expect that these robots will have a higher life expectancy than normal humans since they are immune/resistant for many natural causes of death. That said, I still don't think that they will be immortal, nor live much longer than maybe 80-130 years (on average).

Why that? Well, human brains still consist of cells, and cells have a life span of their own. During their lifetime, they can replicate themselves, but the number of "cell generations" has a limit. Every new cell generation loses a bit of DNA information (normally some garbage DNA, but once that is used up, "real" DNA content goes missing), so the maximum lifetime of a human brain is fixed in this regard.

Also, don't forget about the human psyche itself. Humans originally were at the peak of their lifespan at an age of 30-40 (think of some thousands of years ago), so our brains development reflects on that. People after 30 are not that flexible in their mind anymore, and older people (60+) might begin to feel deficiencies in their minds ("getting senile") that grow stronger the longer they keep on living, until some of them aren't capable of caring for themselves anymore. (This might be caused by cellular degradation, but I think it might be anchored deeper in human psychology itself, although I don't have any sources to back that up right now.)

So, just having an "immortal" body does not mean that the mind can handle that long of a lifetime.

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  • $\begingroup$ This seems like a problem regarding error correction. If the mechanisms used in ECC memory could (correction bits) be replicated through genetic engineering the problem could be solved. The energy needs, and possibly the brain efficiency could suffer but this could be compensated by heightened nutrient input and mildly increased metabolic intensity. If the civilization is advanced enough to put a brain into a robotic body, it should be in their capabilities to do a bit of sophisticated genetic engineering too. $\endgroup$ – WalyKu Jun 28 '16 at 12:06
  • $\begingroup$ The question states "physiologically normal human brain" and "the brains are not genetically altered", so your comment would be outside of this scenario. On the other hand, if you were able to prevent the DNA information loss on cell duplication, why would you need a robotic body for a human brain? $\endgroup$ – hoffmale Jun 28 '16 at 12:56
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    $\begingroup$ @hoffmale I think you are confounding telomere loss during mitosis with somatic mutations. Telomere loss is the "countdown clock" for cells, but doesn't affect protein producing DNA sequences. Somatic mutations affect the chromosome (most of which is junk DNA) but if it affects an expressed gene then it could cause a problem. $\endgroup$ – Jason K Jun 28 '16 at 13:30
  • $\begingroup$ @JasonK I know that I am no biology expert myself, so do take everything I say in that regard with a grain of salt. That said, I know that telomere loss (thanks for the name!) normally only affects junk data in the DNA, but I also know that this junk data is limited, which means, after the junk data comes some non-junk data. I don't know exactly what this non-junk data represents, so this non-junk data does not have to be a protein producing sequence (e.g. it could be a simple marker "real DNA starts here"), but it is important enough that mitosis goes awry once this data is lost. $\endgroup$ – hoffmale Jun 28 '16 at 14:16
  • $\begingroup$ @hoffmale Telomeres have a purpose, so I wouldn't call them "garbage DNA". The term "junk DNA" is usually reserved for non-coding sequences within a chromosome, and even then, they may have value (even if it is to soak up DNA damage). But yes, functionally you are basically correct. $\endgroup$ – Jason K Jun 28 '16 at 15:11
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If this machine is as reliable as indicated, then diseases that kill the brain but originate from other organic failures (liver failure, heart disease) would be gone. You would still have to worry about cancer, but since you only have a single body part capable of getting cancer that also is at a much lower risk. All in all, the brain is still vulnerable, but removing ways that kill you not originating from the brain should increase the expected lifespan of a significant fraction of the population.

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    $\begingroup$ The brain could be shielded to prevent against all the usual causes of cancer (i.e. radiation). $\endgroup$ – Kodos Johnson Jun 28 '16 at 0:18
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    $\begingroup$ outside causes only increase the chances of cancer. it will happen anyway, just from expected errors in cell reproduction (not planned, but like car accidents, they happen despite measures taken to prevent problems). $\endgroup$ – Karen Jun 28 '16 at 13:14
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The problems I have with the scenario of a "brain in a vat" remind me of the problems I had with the movie "Interstellar", in which astronauts try to find a planet to which humans could emigrate because planet earth's ecosystem is degrading.

Whatever the state of earth's ecosystem, it will be orders of magnitude closer to what we need than any exoplanet.

The reason is that we are very well adapted to it, because we evolved together. The same is true for our bodies with respect to our brains, compared to any "exobody".

More radically, the notion of a brain distinct from our body is missing the point as fundamentally as the notion of a humankind distinct from earth.

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    $\begingroup$ Personally I don't agree with the comparison: we might be able to make a robot brain interface that emulates our body really well. We can design robots ourselves for that purpose, unlike planets. $\endgroup$ – Ciro Santilli 新疆改造中心法轮功六四事件 Jun 27 '16 at 21:03
  • $\begingroup$ @CiroSantilli巴拿馬文件六四事件法轮功 If you can design a brain interface that emulates our body really well, can't you just emulate the brain? $\endgroup$ – endolith Jun 28 '16 at 1:05
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    $\begingroup$ @endolith not sure it is a direct implication, but it would definitely help a lot. Still, it is possible that people would still want the "bio brain experience". $\endgroup$ – Ciro Santilli 新疆改造中心法轮功六四事件 Jun 28 '16 at 2:31
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    $\begingroup$ @JohnKeates Well, stroke is a common reason for death or incapacitation in old people. The brain is part of the body and degrades for much the same reasons together with it. If you have medical methods to keep it alive for much longer than the rest of the body, you have medical methods to keep the rest of the body alive as well. In particular, you must keep the blood vessels healthy, whose failure is the major reason people die these days in the US. $\endgroup$ – Peter - Reinstate Monica Jun 28 '16 at 4:54
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    $\begingroup$ Ciro, I think the point is that if your biotech is at the point where you can design a robot body or other effective brainvat, you have probably had the ability to keep a human body alive indefinitely for some time already. $\endgroup$ – SudoSedWinifred Jun 28 '16 at 19:50
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Yes, an isolated brain SHOULD have a substantially extended lifespan, with a few caveats.

For starters, removing the biological body should eliminate many other reasons for premature death (infection, trauma, organ failure, cancer) which will boost the average life expectancy. This assumes the synthetic body is at least as effective as our biological ones and allows for easy replacement of worn parts. The brain case may also be much better at protecting the brain, preventing microtrauma and coup-contrecoup injury from impacts. Cerebrospinal fluid (well, maybe just cerebral fluid now) would be full all the time, so no dehydration related increase in brain injury.

Second, isolating the brain should allow for a "perfect" diet for maintenance of non-neural support structures (preventing cholesterol plaque buildup in the blood vessels, appropriate nutrients with omega-3 fatty acids, etc) which will optimize the potential of the organic tissue. This assumes a thorough understanding of the nutrient requirements of the tissue and an ability to supply these organic and non-organic nutrients. Doping the brain with telomerase and other substances (at this level of tech, probably tailored viruses and nanomachines) to prevent/repair genetic damage, telomere depletion, and terminal blood vessel injury would prevent accumulation of eventually fatal damage to the brain and support structure.

Third, toxic substances/scenarios should be limited. Alcohol, for example, may not be a concern for an isolated brain. Fluctuations in blood pressure should be limited, both elevated pressure which could rupture blood vessels and cause strokes and drops in pressure which would lead to hypoxia. It may also be possible to inject protective compounds when necessary (for example, THC has been shown to be very protective in reducing traumatic brain injury following impact). Preventing heavy metal toxicity may reduce some debilitating neural diseases (some linkage to Alzheimer's) and prevention of infection may also help.

Presumably isolation from the body would cause SOME problems though. There is literature to suggest that some neurotransmitters are actually manufactured by the GI tract, so that would have to be replicated. Even if synthetic blood can replicate O2/CO2 exchange and waste removal, the immune system and some sort of bone marrow analogue would be necessary. A stockpile or means of generating pluripotent stem cells would also be necessary, as we learn more about the brain it does not appear to be as static as we once thought. There are also feedback mechanisms that reply on organs south of the brain, these would have to be artificially regulated. There are also protective neurologic reflexes and sympathetic/parasympathetic feedback systems that would have to be replicated in a synthetic body lest the isolated brain fail to respond appropriately to damaging external stimuli.

Psychologically of course eliminating the biological body carries an enormous risk. We rely heavily on feedback from our body to develop our psyche and conduct the "normal business" of living. For example, folks with a feeding tube who no longer need to eat report a significant drop in quality of life because the dopamine reward system associated with physically tasting and chewing food is now absent. I suspect, much like the examples provided by Robocop 2, it would require a special psyche to be able to adapt to a synthetic body unless it PERFECTLY recreates the experience of being human. Otherwise supplanting the body's reward mechanisms with drugs would probably be pretty common.

EDIT: I'll mention some other considerations that tangentially at least will affect brain lifespan. Currently at least, interfacing biologic systems with synthetic ones is very problematic. Even something like a prosthetic limb causes irritation where it joins the body. For an isolated brain nerve endings would have to mate with synthetic components, both for sensory input and for motor action. Now there is some possibility that you could induce sensory input/derive motor output remotely by magnetically reading the brain and stimulating certain areas but this would probably be VERY low bandwidth for quite some time. So instead you have to hook up cranial nerves (there are twelve pairs of them) to sensors, at least the important ones for vision, smell, taste, etc. So a biological nerve interfacing with a synthetic sensor, even if it doesn't directly connect (instead using some sort of neurotransmitter gap) will typically stimulate an inflammatory reaction. This can be downregulated with corticosteroids/immunosuppressants, and indeed without a body and bone marrow the isolated brain may have NO INTRINSIC IMMUNE SYSTEM, thus it would be very vulnerable to any introduced microorganism, so it's nutrient supply and components would have to be rigorously sterilized and the cerebral fluid would need constant monitoring so anti-microbial anti-biotics/nanites could be introduced. But an immune system also helps destroy emerging cancer cells, so there would have to be a system to perform that task as well. Now it is possible that your synthetic body is in fact at least partly organic itself (i.e., built using carbohydrates, lipids, and proteins, utilizing chemical gradients and biochemical processes rather than mechanical ones) which may reduce the inherent difficulty in getting organic tissue to work well with mechanical parts (I'll just assume that graft vs host rejection has been resolved at this tech level). You also have to consider how you would map the severed spinal cord trunk to whatever interface conducts motor neuron impulses to the synthetic body (as it seems like you intend for this brain to have a humanoid robot body). This process is difficult to mass produce because currently our brains "learn" which neurons do what as we grow and the spinal cord wiring isn't necessarily the same from person to person. But it ought to be roughly similar enough that a new brain/body would have some level of control, but they would have to go through some intensive physical therapy while their brains rewires itself to accommodate the way the new body functions. This spinal cord interface would also have the same organic/machine interface problems as sensory nerves.

Anyway, very long winded way to say that the complexities of the brain/machine interface itself could lead to degradation, inflammation, and serve as a nidus of infection. Constant low level inflammation is associated with increased incidence of cancer. So it is quite possible that an entire new set of diseases crops up around these hybrid organisms, which may negatively impact their lifespan.

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  • $\begingroup$ The technological difficulties you mention are very interesting. I hadn't thought about it, but it must be very hard to provide the exact required brain API, specially in a machine the size of a body, without an actual body. Maybe this tech will never happen. $\endgroup$ – Ciro Santilli 新疆改造中心法轮功六四事件 Jun 28 '16 at 15:47
  • $\begingroup$ To be fair, our biological bodies have millions, in some cases hundreds of millions, of years to adapt the mechanisms we use. Our current form is a few hundred thousand years old. There is a distinct holistic experience with being human that modern (western) society often overlooks. Artificially replicating it would be a significant challenge. I suspect initially an isolated brain would have a SHORTER lifespan, but we'd get better :) $\endgroup$ – Jason K Jun 28 '16 at 16:42
  • $\begingroup$ This made me think that it would be more "likely" that we will have a lot of brains on a huge brain farm, to factor out the maintenance. Then those brains can either control robots outside if bandwidth is good enough, or live in (possibly less interesting) world simulations. $\endgroup$ – Ciro Santilli 新疆改造中心法轮功六四事件 Jun 28 '16 at 17:48
  • $\begingroup$ @CiroSantilli巴拿馬文件六四事件法轮功 Functionally it probably wouldn't make a difference. Since the isolated brains would need an artificial gyroscope to replace the inner ear as well as total sensory input replacement, they probably wouldn't even know (or care) if they were physically inside a robot body or just remotely piloting it (though the smarter ones might be able to figure it out based on input lag). $\endgroup$ – Jason K Jun 28 '16 at 18:10
  • $\begingroup$ Sure, what I mean is that the farm might be cheaper / easier to make than embedding the brain. There are of course bandwidth / latency limitations of remote control. $\endgroup$ – Ciro Santilli 新疆改造中心法轮功六四事件 Jun 28 '16 at 18:18
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Brains get sick and die, just like the rest of our organs. That said, removing all the other causes of death from the equation would increase life span, sure.

However, even brains in a box (or whatever) would be susceptible to prion diseases (such as Creutzfeldt-Jakob disease), neuro-degenerative diseases (such as Parkinson's disease), biological agents (some microbes cause damage to our brains) and eventual death. Nothing has an indefinite half-life, and all the cells in our bodies die off over time, brain cells included.

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One thing often referred to in the medical world around life/death situations is the "quality of life". When one's own limb is damaged a significant amount of rehab is undergone in order to recover. This is not only physical but also a very emotional process. Depending how advanced this "robot" is will severely impact the true extension of life. Even if the input/outputs are the same imagine your voice, sight, abilities, sexuality, and everything you know changing in an instant. I simply don't think it would be possible to maintain the "quality of life" and the individual would feel trapped. So in this way it is in my opinion that an older brain (assuming that's when this would take place based on your question) would be far to tired to handle the stress of the transplant and rehab.

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    $\begingroup$ If this technology ever becomes mature, I suppose people would transfer brains to machines ASAP as babies to prevent death, possibly changing the robot like changing a shoe that becomes too small. However, if the IO simulates your body really well, I think most people wouldn't feel much difference. We are more trapped in our current bodies than in such replaceable bodies :-) $\endgroup$ – Ciro Santilli 新疆改造中心法轮功六四事件 Jun 27 '16 at 19:11
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    $\begingroup$ This is a good handle on things. Also referring sex as an input/output made me giggle $\endgroup$ – Marshall Tigerus Jun 27 '16 at 20:50
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    $\begingroup$ Voice wouldn't be an issue if voice production technology was researched enough (presumably a civilisation advanced enough to create a mobile life support system for a brain would be capable of creating an advanced voice emulation system) $\endgroup$ – Pharap Jun 28 '16 at 2:41
  • $\begingroup$ This is a matter of marketing. You want the people to want to upgrade. Realistic experience is meh, realistic experience except you are now 30 + known afterlife is a nice bonus. And if people just don't want to upgrade? Tough luck. They might discover that as more and more people migrate to vats, it will become increasingly difficult to find the resources necessary to maintain a physical body. $\endgroup$ – John Dvorak Jun 28 '16 at 5:31
  • $\begingroup$ @MarshallTigerus I have no doubt that sex tech / orgasm button would be one of the first applications of such tech, much like every other media tech we have today :-) $\endgroup$ – Ciro Santilli 新疆改造中心法轮功六四事件 Jun 28 '16 at 9:08
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I can't give a number, but it might be helpful to know that cells themselves age and degrade with time. That is to say, cells are replaced throughout life by newer cells made to cell division, but the new cells will be identical to the previous, including age.

I'm not very good at explaining it, but eventually the cells will still degrade and break down, or the DNA gets damaged, and you will die. It would probably give a significant increase to lifespan because the brain is the only organ left to die.

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Well let's say a roboter has the human brain and it's shielded from radiation and other attacks from outside you could most likely live forever.

Why is this?

  1. You have no vulnerable body parts.

    You are shielded by some sort of metallic body and therefore can't be killed that easily.

  2. Science is way more developed.

    It's not that important for your specific question, but if we assume, that we can connect a human brain to a life supporting vessel and can get signals from it without failure, there will be advanced biology as well. The reason for us to get older is, that every time our cells devide you loose a bit of your DNA ("blueprint"). With advanced technology we will be able to make our DNA very long so we live a lot longer. If you now also look at the fact, that the cells of the brain devide slower than average cells we could live really long.

So in conclusion I would say, that ones life expectancy would be considerable increased.

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I'm no biological scientist but some concerns come to mind regarding the complexity required to actually sustain the brain:

  • Immune system: with no facility to create white blood cells (e.g. bone marrow) how will disease and pathogens be controlled?
  • Hormone control: since the brain largely produces and depends upon hormones that usually go into/from the body, how will the level of all hormones be controlled
  • Stimulus: Since the brain would be a living thing it would need a similar range of stimuli as a human being otherwise its entire structure may change and potentially become far removed in function from its intended form.

I think it would all depend on how advanced the infrastructure is - you're talking about thousands of years of continuous improvement versus a few years of development

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A combination of regenerative stem cell treatments and cancer targeting oncolytic viruses could keep the brain functioning even if the loss of neurons means the mind will gradually lose memories, which might actually be beneficial for maintaining sanity over an extended lifetime.

Or if the oncolytic viruses are too destructive (and assuming the regenerative treatments can keep up) the mind could be reduced to a confused childlike state, quick to learn but also quick to forget.

Phantom limb syndrome could also be a major issue, suddenly losing feedback from the heart, lungs, bowels and every other part of the body may cause the brain's automatic functions to react in unpredictable ways.

Still, live forever or die trying ;)

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    $\begingroup$ I don't think you'd have phantom limb syndrome, since the robot form and brain interface closely resembles your body. $\endgroup$ – Ciro Santilli 新疆改造中心法轮功六四事件 Jun 28 '16 at 2:37
  • $\begingroup$ Are you writing near-future speculative fiction or planning on this for yourself some day? In the latter case BCI technology isn't that advanced yet, implantable electrode arrays do enable two way communication but its analogous to hacking a telegraph into the internet, crudely. $\endgroup$ – Cognisant Jun 28 '16 at 2:49
  • $\begingroup$ I strongly believe that this tech will happen some day, but not in my lifetime. Just an engineer doing some for-fun speculation, not writing anything either. $\endgroup$ – Ciro Santilli 新疆改造中心法轮功六四事件 Jun 28 '16 at 9:06
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Brains can not regenerate neurons without stamina cells which it has in low quantity. If stamina cells is provided then it could have an incredibly longer lifespan.

Given the brain is perfectly protected from any external danger

The only thing that could kill it is ''poop''

Brain cells stack up piles of waste inside them until it kills them. Having a system that cleans the cells would make the brain immortal.

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  • $\begingroup$ Where do stamina cells come from? $\endgroup$ – Ciro Santilli 新疆改造中心法轮功六四事件 Jun 28 '16 at 12:33
  • $\begingroup$ We are born with them, they are basically ''universal'' cells capable to become anything and are the only cells capable to become neurons. The stem cells you can buy in some hospitals come from Umbilical cord blood extracted from kids after they are born. $\endgroup$ – άθλια βδέλυγμα Jun 28 '16 at 16:53
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I think there's two possible answers to this problem. We could assume that our "vat" is only as good or worse at maintaining a functioning brain as a human body would be, in which case the brain-in-a-vat would only have a lifespan equivalent to a sequestered full-body human. The other answer would be to assume that the "vat" incorporates technology that prevents some number of the ways that human brains could die or grow old, or all of them, in which case the brain could live longer or indefinitely.

The problem with the second kind of answer is, why couldn't we apply these technologies to full-body humans? Telomere lengthening, perfect diets (even full control of metabolism through constant blood replacement), enhanced cellular waste disposal, etc (to take few ideas from other answers) don't only work on brains.

To fit a story, perhaps you might say that keeping someone immortal is expensive and costs more per unit biomass, so going brain-only is thrifty.

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  • $\begingroup$ We could assume that this vat provides a optimal diet / waste disposal for the brain, possibly better than an actual body, and I would love to know it the life of the brain would be increased by that (although I suppose no one knows?). But it would likely be easier to maintain this optimal condition to a brain alone instead of a whole body, simply because it is smaller. And maybe, we can make the brain condition more optimal by isolating it than we could if we had to go through an entire body first. $\endgroup$ – Ciro Santilli 新疆改造中心法轮功六四事件 Jun 28 '16 at 15:55
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@hoffmale has as great answer! That said, while not increasing life expectancy directly, the indirect affects could increase an otherwise doomed physical existence. Of course, none of this discussion takes into account the mind or soul and the part that plays in a persons existence. But let's set that aside for now and just assume it transfers with a person's consciousness, as dictated by a normally active and functioning brain.

Let's start with the brain.
It will still need to be "fed" oxygen and other critical nutrients. These nutrients could be fed "pure", filtering out all of the contaminants that can cause disease and decay. This in itself could prolong life and make the "person" impervious to toxic environments, short term anyway, and disease.

The "vat" or brain bucket, cranium, whatever you want to call it, can be made of much tougher materials than organic bone in addition to better impact dampening than is present in a human skull. Better brain protection can prolong life.

This technology could also extend the life of a terminal patient.
Transplant patients that can't get an organ in time, cancer patients, genetic defects, catastrophic injury, etc. These people would definitely see a longer life!

Kids would benefit the most!
Kids with these issues or genetic defects that seriously hinder quality of life would be able to experience a full life! If the transplant process is not too traumatic, you could, conceivably, transfer the child to larger more adult like robots as they matured. And if a child is best identified by their brain, would abortion continue to be legal?

Think about the ramifications of halting death until its natural outcome was reached!

  • What breakthroughs could be made when a human brain inside a robot can withstand so much more?

  • How much tragedy could be avoided and the after affects of that tragedy?

  • What would the point of traditional war be?
  • How many Einsteins, Mozarts, or Michaelangelos would emerge?

While the maximum number of years a person has might not be affected significantly, the life of the human race could potentially be extended.

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