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Previous EA discussions of this topic: here, here, here, and here. Note that these primarily focus on cryonics, although I prefer the term brain preservation because it is also compatible with non-cryogenic methods and anchors the discussion around the preservation quality of the brain. See here for more discussion of terminology.  

This post is split up into two sections: 

(a) Technical aspects, which discusses why I think preserving brains with methods available today may allow for revival in the future with long-term memories and personality traits intact. 

(b) Ethical aspects, which discusses why I think the field may be among the most cost-effective ways to convert money into long-term QALYs, given certain beliefs and values. 

In this post, I’m not discussing whether individuals should sign themselves up for brain preservation, but rather whether it is a good use of altruistic resources to preserve people and perform research about brain preservation. 

Technical aspects of brain preservation

1. What is the idea behind brain preservation? 

a. Brain preservation is the process of carefully preserving and protecting the information in someone’s brain for an indefinite length of time, with the goal of reviving them if technologic and civilizational capacity ever progresses to the point where it is feasible and humane to do so.

b. Our society’s definition of death has shifted over time. It depends upon the available medical technology, such as CPR and artificial respiration. In the future, the definition of death will almost certainly be different than it is today. One possible improved definition of death would be when the information in the person’s brain that they value is irreversibly lost, which is known as information-theoretic death.

c. Pausing life without causing information-theoretic death could be done with a long-term preservation method that is not yet known to be reversible today, but which has the goal of preserving enough information in the brain so that it could potentially become reversible in the future with improvements in technology. This is brain preservation. 

d. With current methods, we can potentially preserve enough structure in the brain over the long term to retain the information for valued cognitive functions like long-term memories. There are multiple possible methods to attempt to accomplish this, each with upsides and downsides. 

e. Plausible methods for the revival of people following brain preservation include whole brain emulation or off-board molecular nanotechnology-based repair

2. What in the brain is necessary to try to preserve? 

a. It is already possible to stop electrochemical neuronal activity (in humans) and biological time (in other animals) without loss of long-term memories. The cognitive functions that most people care about seem to be encoded by static structures in the brain. More on this here

b. Adequately preserving the brain alone would be enough to retain the information for long-term memories and core personality traits, because it is the only part of the body that is known to be irreplaceable without massive effects on this information. More on this here

c. Despite currently lacking complete models, we can use existing knowledge in neuroscience to evaluate the hypothetical process by which structural information for valued cognitive functions could be mapped in the future. More on this here

d. A wealth of evidence suggests engrams are encoded in neural structures distributed across the brain. More specifically, it seems to be the distributed activity of neuronal ensembles communicating through the biomolecule-annotated connectome that instantiates long-term memory recall. More on this here

e. Because of the correlated nature of structural information in the brain, it is likely that there are numerous topological maps of the biomolecule-annotated connectome that could retain the information needed for long-term memories. Even if many of these maps were damaged or destroyed by aspects of the brain preservation procedure, if at least one could still be inferred, then the information content would still be present. In the future, our inference capacities are likely to improve dramatically as a result of AI, making the inference of sufficient structural information in the preserved brain much more plausible. More on this here. (This is assuming that humanity survives the transition to transformational AI.)

3. What are the methods we can use to try to preserve structural information in the brain? 

There are numerous possible ways to do so. Broad categories include: 

a. Unprotected cryopreservation (also known as “straight freeze”). In the absence of cryoprotective agents, ice will certainly form during low subzero cooling and will mechanically crush cellular structures, leading to damage to the connectome. The question is whether that damage is enough to cause information-theoretic death. There is some evidence that structural preservation quality following unprotected cryopreservation may not actually be that bad (for example, Aschwin de Wolf discusses this here), although this is one of the most controversial questions in the field, and others vehemently disagree. Neural Archives Foundation offers this option in Australia, which costs AUS$30,000 (~$22,000 USD). 

b. ​​Cryopreservation with cryoprotective agents. By perfusing cryoprotective agents into the brain, ice formation and associated damage can potentially be prevented. Unfortunately, getting cryoprotective agents into the brain is a difficult problem. Also, this causes dehydration and associated damage to brain structure. However, Greg Fahy’s team at 21st Century medicine has reported that they can achieve good preservation quality with their cryoprotective agent perfusion protocol; for the most recent details on this, see page 496 of Robert Freitas’s book. Cryonics Institute offers this option for ~$30,000 for people who live locally in the Clinton Township, Michigan area. 

c. Aldehyde-stabilized cryopreservation. Aldehyde stabilized cryopreservation was introduced as a whole-brain preservation method in 2015. It has two main steps (to oversimplify quite horribly): aldehyde fixation, followed by cryopreservation. The fixation step seems to help with the distribution of cryoprotectants to the brain. The reasons for this aren't quite clear to me but likely involve quickly stabilizing the structure of blood vessels and/or cell membranes. 

For this method, 21st Century Medicine (where Robert McIntyre and Greg Fahy worked) won the Brain Preservation Foundation prizes -- the small mammal prize in 2016 and the large mammal prize in 2018. These prizes were for showing that the method could preserve the microstructural anatomy (i.e. the connectome) of whole brains using a method that would be capable of storage for the long term -- at least 100 years. Clearly, aldehyde stabilized cryopreservation is an extremely promising approach for people who prefer brain structure preservation. Oregon Cryonics is currently offering an option similar to this for $28,000. 

d. Fixation followed by long-term liquid preservation in aldehyde. Aldehyde fixatives act to preserve tissue primarily by covalently cross-linking biomolecules, mainly proteins. This dramatically strengthens natural gel-like structures in the brain such as the cytoskeleton and extracellular matrix and has been shown to cause gel formation in brain tissue. Gel formation is a way for a liquid to have solid-like properties and stability. Vitrification and gel formation actually share many biophysical properties

Might gel formation alone be sufficient to preserve brain structure for the long term? There are some studies suggesting that neuronal morphology is maintained for decades when preserved even at room temperature in formalin. One study found that neuronal morphology was well-preserved in brain tissue stored in formalin for 50 years. Another study found that there was “excellent preservation of fine and even cellular details in the tissue” in brain tissue preserved in formalin for ~80 years. Formalin only came into use in the 1890s, and there isn’t that much brain tissue preserved this way for such a long time, so it’s unclear how long this tissue would maintain its structure. There are also a lot of biomolecular alterations resulting from formalin storage, although they may not be sufficient to cause information-theoretic death. 

Oregon Cryonics is currently offering liquid preservation in aldehyde for $1000. When combined with the fees of a local funeral director or pathology specialist to do the initial preservation, the total cost for this is likely around $3000-10,000. Note that the average funeral cost in the US is around $7000

e. Fixation followed by plastic embedding. For example, brain plastination. This offers the potential for more stable long-term preservation at ambient temperatures. As far as I know, this is not currently offered anywhere in the world. 

Fixation-based options (#3-5) are potentially more scalable because they offer the possibility of tapping into the existing brain banking infrastructure, which exists in much of the world. However, doing so also depends on how long one can wait following legal death but prior to starting the preservation procedure, which is another unknown question.  

I want to be clear that I am not endorsing any of these organizations. I am just listing these prices for the purposes of discussing how much brain preservation currently costs because this is clearly relevant to its potential as an effective altruism cause area. Hopefully, it is apparent that there is a range of possible approaches and that room temperature methods in particular have the potential to be quite cheap. 

Open questions

- Which structural aspects of the brain are necessary for preserving the information contained in long-term memories and personality? 

- Which brain preservation method is the most cost-effective way to preserve a sufficient amount of brain structure for long-term memories and other valued aspects of personal identity? 

- Can we improve the expected structural preservation quality of room temperature options using methods that are still cheap? 

- How long can one wait after legal death but prior to starting the brain preservation procedure, without causing information-theoretic death? 

Ethical aspects of brain preservation as an EA cause area 

I'm going to discuss four areas here: importance, tractability, neglectedness, and scalability. 

Importance: To the extent that it might work, the ethical importance of brain preservation is very high, from both a QALY improvement and QALY extension perspective. 

1. QALY improvement: The badness of involuntary death – for oneself, one’s loved ones, and others (including non-human animals) – is a huge psychological burden on most people. Involuntary death is widely considered one of the great harms of life, even by anti-natalists. An influential psychological hypothesis, Terror Management Theory, shows that people find the idea of death so aversive as to ward off even thinking about related topics. Even if brain preservation was credibly seen as giving people an optional and realistic chance at living longer, this could be a valuable improvement to people’s quality of life, as Tim Urban has discussed

2. QALY extension: If brain preservation is successful and the person is revived, then they are likely to be revived in a future in which aging and many other forms of death are no longer a problem, either through improved biomedicine or via whole brain emulation. This has the potential to create an enormous number of QALYs. 

There is a question of how long humans can live in a way that achieving a QALY would still be possible. Some feel that living a high-quality life for thousands of years is not possible. However, I’m not sure where people are getting this from, especially given the vast and obvious quality of life improvements that one could imagine in the future. For the purposes of these calculations, I will assume 10,000 QALYs is possible, given the potential for playing games, exploring the universe, understanding the secrets of the universe, learning about the past and future, connecting with other people, etc. One can imagine 10,000 QALYs as being like living 100 different lives, each 100 years long. Given the vast diversity in lives imaginable, if anything, 100 seems to me like an underestimate. If one assumes that more QALYs than 10,000 is possible, then subsequent calculations become stronger (and vice versa). 

As of 2016, one estimate is that via bed nets for malaria prevention, $3500 buys 35 QALYs, or $100 per QALY. On the other hand, if a brain preservation procedure costs ~$10,000 and yields 10,000 QALYs, it has the potential to have a cost of $1 per QALY. Naturally, a key question is what is the probability of successful revival from brain preservation. If the probability of success is 1%, then brain preservation would be at $100 per probabilistic QALY, on par with bed nets for malaria prevention. Given our uncertainty in probability estimates, then more research to determine the probability of the success of brain preservation also seems very valuable. 

One might argue that it is unfair to distribute all of the QALYs to one person and that they should be shared more broadly. However, there is no reason that ​brain preservation ​could not be made available to everyone who wants it. 

Others might argue that these QALY arguments are misguided because future society will be able to create more people at will. For example, as Nuno Sempere describes

> One could also argue "that cryonics doesn't create many additional QALYs because by revival time we've probably hit Malthusian limits. So any revived cryonics patients would be traded off against other future lives." 

As I discuss above in QALY improvement, I disagree with this viewpoint that humans are fungible and one can just create more people to achieve the same QALYs, because of the psychological and relational harms caused by involuntary death. But, if someone views humans as replaceable, then I can see why they might think that brain preservation doesn’t really create many QALYs over alternatives possible in the future. 

3. Brain preservation may also have effects on people’s propensity for long-term thinking. Having more “skin in the game” for humanity’s future may make people’s behavior more pro-social. This is much discussed and seems plausible. But it also could have complicated second-order effects and seems hard to precisely estimate, so I don’t consider it an EA reason to promote brain preservation.   

4. Brain preservation doesn’t seem to contribute to S-risks. For example, if an S-risk were to occur via a malevolent AI that wanted to torture humans, then that AI could simply simulate human minds sampled from mindspace, regardless of whether those people had chosen to pursue brain preservation. 

Tractability: Uncertain. Structural brain preservation is already possible and already happening. On the other hand, revival is very much not happening. In my opinion, it is very difficult to know what the probability of success of brain preservation is. There are ways to bound it based on societal factors (for example, the probability of social collapse), but the core problem of sufficient preservation quality is very challenging to predict and is correlated with other forms of uncertainty in the project

I have studied this topic for years and I have no idea how people are making these probability estimates. Aggregating success probability estimates by those individuals who are willing to speculate despite our current uncertainty doesn’t seem very helpful. Revival also seems to be too far away for a working prediction market given today’s prediction market methods. Instead, all we can have today is feelings about how likely it is to work. So for tractability, opinions likely vary significantly. 

Neglectedness: High. There are very few people in the world working full-time on structural brain preservation research for the purposes of preventing involuntary death; probably less than five to ten people. There are also few working full-time on preserving people; probably less than twenty-five to fifty people. 

The practice is also highly stigmatized. Brain preservation is thought to run contrary to societal mores and break taboos regarding death. For example, Tucker Carlson called cryonics “obviously grotesque and ghoulish and kind of revolting”. This is a win from a neglectedness perspective because it suggests a clear reason why it is neglected that is orthogonal to its likelihood of success. 

Scalability: High. One survey suggests that around 6% of people have already decided to pursue cryopreservation, although they currently lack options to do so. With 178,000 people dying per day, a naive extrapolation means that brain preservation has the potential to probabilistically dramatically extend the QALYs of 10,000 people a day if the infrastructure to perform this was expanded. 

Another survey suggests that around 20% of people could imagine doing brain preservation. People would probably be more likely to actually do it if it were a more widespread practice and cheaper. 

Open questions

  • How much might the possibility of not definitely undergoing involuntary death improve people’s quality of life today? 
  • How many QALYs are possible for a human to experience assuming an indefinite lifespan?  
  • Are lives fungible, so that if one person dies we can just create another one with no significant loss to QALYs? If not, how should this affect our QALY calculations for brain preservation? 
  • How will future society feel about creating more people until reaching Malthusian limits? 
  • Given low costs (perhaps around the same cost as a typical funeral or less), what percent of people would be interested in brain preservation? 


It seems to me that: 

(a) Most current technical arguments against brain preservation, to the extent that there are any at all, don't grapple with the possibility of structural inference.  

(b) Most extant arguments in the effective altruism community against brain preservation as a cause area don't grapple with QALY improvement/extension, and for unclear reasons treat humans as replaceable units, neglecting relational and psychological factors. If people think humans are replaceable, I think they should justify this, and also consider whether they are being consistent about it. 

(c) With today’s methods, brain preservation may already be among the best altruistic investments available from a QALY improvement/extension perspective, given reasonable estimates about the probability of success. 

(d) With more research, substantially cheaper methods for structural brain preservation could potentially be developed, which could further improve the cost/benefit calculus. With more research, our uncertainty about different aspects of the brain preservation project could also be better clarified. 

As a result of the above, and given its neglectedness, I think brain preservation for the prevention of involuntary death is one of the best areas for people interested in helping others to work in. I also think it is a great place for people who are interested in helping others to donate money. If you disagree, I would love to hear from you why that is. If you agree, I would love to discuss with you practical topics of how to best improve the field. Thanks for reading! 

Further reading

- Francesca Minerva is a leader in the ethics of cryonics. She has a book on the topic here and has a video discussing QALY extension via cryopreservation here; both are recommended if you’re interested in this topic. 

- The Brain Preservation Foundation website: https://www.brainpreservation.org/

- John Smart’s essay: “Do we need a noncryogenic brain preservation prize?” 

- My in-progress essays on brain preservation (feedback welcome!): https://brainpreservation.github.io/ 

Sorted by Click to highlight new comments since:

You didn't mention what I see as one of the biggest considerations: that current cryonics costs are dominated by fixed costs, because there are so few current customers. WIth a lot more customers the chance of success could also go way up. 



Are there any other products that could be leveraged by current cryonics facilities that could also help decrease those costs in the interim before moving to plastination? I know sperm storage is becoming increasingly popular; maybe there are other products that someone already interested in cryonics would also be interested in that could leverage the facility?

Thanks for the effortful post Andy! I agree so strongly with the importance of exploring this topic that I am halfway through writing a book on the subject. I'll respond to the technical points first, than the ethical ones.

Regarding some of the technical points:

  • Cryopreservation with cryoprotective agents, but without prior aldehyde fixation, produces unavoidable brain shrinkage of around 50%. Although it's possible that all important structural and biochemical information survives this shrinkage, it's very plausible that critical synaptic connection information will be lost due to non-uniform shrinkage, tearing or receptor hyperconcentration. Perhaps its better than no option at all, but aldehyde-stabilised cryopreservation provides a much higher guarantee of successful information preservation.
  • The long-term storage costs of an aldehyde-preserved brain is currently an open question, as we're unclear on how cold a brain has to be kept to prevent lipid drifting over the long-run. You do need to keep the brains below room temperature, as otherwise the lipids in the neuron cell membranes will slowly drift and obscure your synaptic information. However, it might be possible to slow this sufficiently at only -20C or so, which will make it much cheaper than the current requirement of -135C.
  • The point of information-theoretic death relative to current legal death very much depends on the condition of the patient during their final dying phase. For someone who suffers a sudden unexpected cardiac arrest, but who was otherwise healthy previously, evidence from the time to synapse degradation following loss of blood supply suggests it may be around 21 hours. For those who already had extensive health issues including poor circulation and liver failure, it may be much sooner. If you're interested, see my sample chapter below on 'What is Death?'

Regarding the ethical points, I mostly just agree with your comments. Deciding whether lives are fungible is a key part of the debate between 'person-affecting' and 'total' utilitarians, and as of-yet unsettled as I see it in the EA community. Even if one takes the total view though, your points that 1) 'people don't like dying' and 3) 'it might improve their long-term planning' are very compelling. 

I strongly agree with the comment Robin Hanson made as well that the current paucity of uptake both reduces the  chances of neuropreservation being successfully implemented (due to a lack of robust infrastructure and auditing) and makes everything far more expensive (due to a lack of economies of scale). I'm fairly certain that at mass scale the preservation procedure could be done for <$5000 and the storage costs would be only a few dollars per year, meaning that it would certainly be a competitive intervention.

If any comment readers are interested in reading a bit more on this, here are two sample chapters from my upcoming book: '1. Why Don't We Get More Time?' and '6. What Is Death?'. Also, I'm currently in the process of looking for a literary agent to get a publishing house to take up my book proposal, so please PM me if you know any agents who would be interested.

Nice to see other people interested in the topic! 

Robert McIntyre, the CEO of Nectome, the brain preservation startup, is probably the person who knows the most about this space.

For those interested, I did a writeup on a talk Robert  gave that summarizes his thoughts and process here:


And I interviewed him here:


Not sure if you considered it as a potential benefit but my understanding is that right now the government and health care systems/insurers spend an inordinate amount of money mainly to extend life for the last 5-10 years of an elderly person now. This imposes broad costs on state run health systems and private insurers which need to charge people more from younger ages to cover these expected costs. It's possible that more elderly people are inclined to engage in cryopreservation just before they enter this "sickly period" (for lack of a better term) if they believe in the future they could be revived helping to spare a huge amount of costs on medical systems today. 


P.S. Great writeup; I've thought occasionally about trying to build a business in the space focused on longevity and making cryo more approachable for the average person. I know some folks in Germany started a startup around it which gives me some hope that it isn't too crazy an idea for venture funders and has some potential for returns.

Thanks for your kind comments! Much appreciated. 

I agree that brain preservation could potentially be cost-saving for healthcare systems if combined with medical aid in dying and people were interested in this rather than pursuing painful care that is likely futile. However, my guess is that healthcare systems in general are not very cost-efficient from an effective altruism perspective, so it's hard to see how this would affect overall QALYs. 

As a former neuroscientist, I am very in favor of brain plastination, particularly of 'soft' plastination (e.g. the CLARITY technique). I think there's a huge amount of long-term cost savings and safety improvement from making the brain info stable at room temperature and easily readable multiple times over without destruction. The value of soft plastination is that you can still infuse antibody labels and such into the tissue to non-harmfully study the tissue. 

The only reason I am not encouraging people to donate to this as a cause area is that it seems so small impact compared to x-risk causes. The people who will live in the next couple hundred years are potentially dwarfed by the people of the far future  so... lets just try to get to the far future without being too self-obsessed. 

That being said, I do hope to preserve my brain and the brains of my spouse and children and their children, etc. It's just a small consideration all things considered.

So if I am understanding right, the main benefit of reviving a preserved brain, over creating a new person would be “relational and psychological factors”. I am interpreting that loosely as friends and family wouldn’t be sad that they are dead.

Is that enough to justify the costs? Presumably, by the time of reviving, friends and family of most people who’s brains have been preserved would either be dead or have had their own brains preserved. The obvious exception being those who died just before the technology developed.

It seems like the question is maybe, how many QALYs would you estimate from friends/family in that situation and how does the cost effectiveness work out for that?

Hi Jeremy, as far as I can tell, nearly all of the QALYs are dependent upon the idea that it's better to extend someone's life than to replace them with a new person. Because by the time that revival is possible, we will likely be able to create new people at will. (This is assuming that society does not decide to not create more people before reaching Malthusian limits.) 

Basically, we get rapidly into population ethics if you want to debate whether lives are fungible. As Ariel points out elsewhere in the comments - I was not aware of this connection, but it seems fruitful - "Deciding whether lives are fungible is a key part of the debate between 'person-affecting' and 'total' utilitarians, and as of-yet unsettled as I see it in the EA community." 

To me, the idea that humans are fungible and that it doesn't matter if someone dies because we can just create a new person, goes so strongly against my altruistic intuitions that the whole notion is difficult to think about. There is a reason that similar reasoning leads to the repugnant conclusion

This is part of why I said "I think the field may be among the most cost-effective ways to convert money into long-term QALYs, given certain beliefs and values"; the idea that humans are not fungible is one of those values. I'm not sure how to calculate the QALYs without assuming that value. I don't think it's possible to quantify the "sadness". Do you have any ideas? 

Thank you for the thoughtful reply. I jotted down the original comment out on my phone and I am realizing it came across more argumentative than I intended. I apologize for that. 

I have similar intuitions that creating a new person doesn't make up for the badness of someone dying, but if it is better, I would like to have an idea how much better and why. 

Assuming we could create new people for some cost, and that those new people have value, it would be important to be able to compare that with the cost/value of reviving someone, to most efficiently spend limited resources.

Focusing on the subject of the intervention, the value of 1000 years lived to a new person would be the same as the value of 1000 years lived to the revived person, no?

The only difference would seem to be the value to anyone else - other people who care about them. 

I can't say precisely how you would quantify that, but additional relevant factors might be

  • how long it might take the technology to develop, and, by that point, how many preserved people would have anyone who cared about them remaining
  • the probability of revival technology working

I'm sure there's more I haven't thought of.

Thanks for this post! It was great to read and learn about a topic about which I know nothing.

My primary reservation, which I'd be curious to get your thoughts on is something like this:

It seems to me that in the abstract there is a finite amount of space available for humans on the planet. Whether that space is taken up by me or some other human being is not too important to me. Similarly to life-extension research it seems to me that brain preservation is spending resources so that people who currently occupy the planet will do so for longer, at the expense of the child that wasn't born due to resource limitations. So the net-value created by extending or preserving life is close to neutral.

What are the counter-arguments to this? Are there weird philosophical bullets I need to bite to hold that position (ie. needing to think malaria is also net-neutral since it creates space for more humans, to remain consistent)?

Thanks for the kind feedback! 

The main counter-argument to the idea that there is limited space is that in the future, if humanity ever progresses to the point that revival is possible, then we will almost certainly not have the same space constraints we do now. For example, this may be because of whole brain emulation and/or because we have become a multi-planetary species. Many people, myself included, think that there is a high likelihood this will happen in the next century or sooner: https://www.cold-takes.com/most-important-century/ 

There is also an argument that we actually do not have limited space or resources on the planet now. For example, this was explained by Julian Simon: https://en.wikipedia.org/wiki/The_Ultimate_Resource. But that is a little bit more controversial and not necessary to posit for the sake of counter-argument, in my opinion. 

A related question is: what is the point of (a) extending an existing's person's life when you could just (b) create a new person instead? I think (a) is much better than (b), because I what I described as "the psychological and relational harms caused by involuntary death" in the post. But others might disagree; it depends on whether they think that humans are replaceable or not. 

There is also a discussion about this on r/slatestarcodex that you might be interested in: https://www.reddit.com/r/slatestarcodex/comments/tk2krv/brain_preservation_to_prevent_involuntary_death_a/i1o2s1d/

I have a few questions on the more practical side of brain preservation. Are there any organisations working on this problem with more room for funding? I know about the Brain Preservation Foundation and Nectome, but as an outsider it is hard to tell how active they are and what they could do with extra money. 

In my opinion, it is very difficult for a company offering brain preservation to hit the market. At the beginning, there are possibly only a few customers scattered throughout the world. You will probably need a standby team at the bed of the terminally ill patient to ensure high quality preservation. This will make the costs skyrocket. The optimal solution would be if a hospital offers brain preservation as a part of their service. However, this seems to be unlikely since the topic is rather controversial. Do you have  thoughts about this problems?  

Thanks for your interest in this topic! 

I agree with you that it is hard as an outsider to tell what the current scope of the situation is regarding the need for more funding. This post was more of a high-level overview of the problem to see whether people agreed with me that this was a reasonable cause area for effective altruism. 

Since it seems that a good number of people do agree (please tell me if you don't!), I am hoping to work on the practical area more in the future. For now, I don't think I know enough to publically say with any confidence whether I think that any particular organization could benefit from more EA-level funding. If pressed, my guess is that the most important thing would be to get more researchers and people in general interested in the field. 

I also agree with you about the chicken-and-egg problem of lack of interest and lack of quality of the service. One approach is to start locally, rather than trying to achieve high-quality preservation all over the world. This makes things much cheaper. An obvious problem with the local approach is that any local area may not have enough people interested to get the level of practical feedback needed, although this also can be addressed. 

I forgot to mention that you should be careful about how brain preservation increases or decreases the probability for suffering or existential risks. On the one hand, many patients waiting for whole brain emulation (WBE) could be a reason to push forward WBE without thinking about the possible negative effects deeply enough. On the other hand, if there are reasons to believe that some people alive today could live for millenia, this may ecourage longterm thinking. Since I cannot determine the sign of the risk, I am cautiously for brain preservation because of the positive nearterm effects.   

I don't disagree with you. Although I think that existential and global catastrophic risks are the most important cause area, there are good project ideas in the life extension community without easy access to venture capital. Since biological aging is a major source of suffering, life extension and brain preservation are worthwhile cause areas.   

This assumes that “reviving” someone, by somehow recreating activity from a preserved brain that has previously fully ceased all activity, is somehow extending/continuing that past consciousness (thus preventing death), instead of creating a similar but separate one (failing to prevent any death). Essentially, the “teletransportation paradox”, just with different flavoring for why/how a working brain is being “destroyed” and later “recreated”.

Is this considered a non-issue somehow?

The short reply to this is that there are already circumstances where people have brains that have completely ceased all (electrical) activity and we don't normally consider people who've gone through these processes to have been "destroyed" and then "recreated". 

This can happen in both cold-water drowning and in a surgical procedure called deep-hypothermic circulatory arrest. In both circumstances, a person's body temperature is brought below 20C and their brain completely stops all electrical activity for ~30 min. When later brought out of this state, people retain their memories and sense of personal identity. Nobody typically treats these people as 'mere copies' of their previous selves.

Anyway, it's a reasonable question and not a "non-issue", but this plus other considerations make it seem not so problematic. Another consideration is the fact that over time you replace essentially all the components of your body through consumption and excretion, so survival can't be based purely on physical continuity either.

As @Ariel_ZJ wrote, it is already possible for brain activity to fully cease and then restart, and people don't typically think that they were "destroyed" and "recreated" after that. 

With some revival strategies, such as whole brain emulation, some people are concerned about a "copy problem", because it would not be the same atoms/molecules instantiated, just the same patterns. Personally, I don't think that the copy problem is an actual concern, for reasons explained here: https://www.brainpreservation.org/content-2/killed-bad-philosophy/

I don't have a short answer for you unfortunately.

The Quantum Physics Sequence does address this to some extent.

Thanks for writing this! I'm interested in brain preservation, and thought maybe this area would be competitive with existential risk stuff given certain philosophical pre-commitments, but now I'm actually not sure.

Even on a person affecting view, I'm not sure this is cost competitive with x-risk. If there are ~8 billion people who would be alive at the time of a human extinction event, then reducing the risks of extinction by 0.01% would save 800,000 of them (on expectation). Doing this might cost $100MM - $1B, for a cost of $125-$1,250/person.

This is cheaper than I think even fairly optimistic estimates of the cost of brain preservation.


  1. This analysis assumes that the people who survive an extinction event would go on to have a similar quantity and quality of life as those who have been preserved. I think this is a reasonable assumption if the extinction event is AI-singularity-shaped, but not if it's something like a pandemic.
  2. Certain methods of reducing extension risk (e.g. civilizational refuges) still result in almost everyone dying, so the cost-effectiveness of X-Risk reduction on person affecting grounds is probably lower than what I'm assuming above.
  3. These caveats might get you the extra 10-100x you need to become cost competitive, but I'm not sure, and even then you're only getting to cost competitiveness, not being much better.

I think I basically agree that if someone can identify a way to reduce extinction risk by 0.01% for $100M-1B, then that would be a better use of marginal funds than the direct effects of brain preservation. 

I don't see high value ways to donate money for this. The history of cryonics suggests that it's pretty hard to get more people to sign up. Cryonics seems to grow mainly from peer pressure, not research or marketing.

Hi Peter, I agree with you that right now there are not any obvious high-value ways to donate money to this area. Although as I just wrote in a comment elsewhere in this thread, I am hoping to do more research on this question in the future, and hopefully others can contribute to that effort as well. 

I also agree with you that the history of cryonics suggests it's hard to get people to sign up. But, I do think that the cost of signing up is an obvious area where interventions can be made. My understanding is that the general public's price sensitivity has not really been tested very thoroughly. 

My main hesitation with cryonics technology is that I expect the marginal cost of providing an extra year of life is increasing as the age goes higher. So I expect making a person live 1000 years would be much more expensive than making 10 people live 100 years each. So I would be interested in arguments on how could marginal costs of increasing lifespan stay constant over age.

My expectation is that in the future, with anti-aging technology or whole brain emulation, aging will not significantly add to the marginal cost of providing another year of life. 

Does this address your hesitation? I'm not sure if you're referring to something else. 

This was what I was referring to. Thank you!

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