I have been thinking a lot recently about the optimal time in life to have one’s brain frozen with the hopes of having it revived in the future. Of course, the field of cryonics is still quite young, so the probability of having one’s brain revived from a frozen state any time in the near future is about as low as the detection of intelligent life elsewhere in the universe within the same limits (see this prior post, and this one), but that shouldn’t stop us from thinking about the particulars of the process. After all, both cryonics and SETI are high-yield scientific long-shots — they are not very likely to yield results at any given moment, but over a long period of time, the chance of discovery or appropriate technological development rises towards significance. At this point in time, though, there are, naturally, several issues that seem insurmountable. In the first, when organic tissue is frozen, ice crystals form that tear apart the tissue, which is particularly destructive for brain tissue. Even when the liquid in the tissue is replaced with antifreeze, we find that the soft neural tissues of a brain will fracture on the microscopic level, leaving the brain largely intact, but with enough micro-fracturing that resuscitation to the pre-freeze state is particularly unlikely. With current technology, it would be like going to bed one day healthy and waking up the next with severe Alzheimer’s. At this point, it’s unknown whether we will ever fully conquer that aspect of the cryonics process — doubtless we will find ways to reduce it, but, looking forward, what seems to be the best possibility for brain-fracture-repair lies in as-of-yet undeveloped nanotechnology. Theoretically, scientists of the future will be able to send microscopic robots through the thawed cryo-preserved tissue to somehow repair all the micro-fissures. Clearly, a solution that is still very much in the realm of science fiction.
However, aside from all the current technological shortcomings, the other aspect of cryonic preservation that is currently wanting rests in the window of a person’s life when their brain can be harvested and stored for future revival. In the present world we live in, taking a brain out of a person who is still alive constitutes either murder or, at the very least, assisted suicide (both of which are, not too surprisingly, illegal). In order to provide the best chances of future revival, then, cryonic specialists have to wait until a person has reached a stage of legal death, after which point the brain may be extracted, prepared (filled with anti-freeze), and inserted into a bath of liquid nitrogen for perpetual(?) preservation. There are downsides to this, naturally. In the first, the task for future cyonicists becomes much more difficult, in that they will have to bring people back from a suspended state of “mostly-dead” rather than from a suspended living state. The cryonics process might be so detrimental to the stored person, as well, that it would take the person from “mostly-dead” to “all-dead,” at which point there’s usually only one thing you can do…. The other major issue to this sort of treatment is that most people at the end of their lives do not have the brains that they did in their prime, and a number of my colleagues and friends have commented that they wouldn’t really want to have their life extended if it’s merely going to draw out the slow decline of their twilight years. (This criticism, naturally, does not apply for preservation after young deaths due to disease or trauma.) So, if end of life preservation is suboptimal, then when is the optimal time to decide to call it quits on current living and place your fate in the hands of future scientists (remembering, of course, that resuscitation from the cryo-preserved state is not a sure bet, and may turn out to be impossible or infeasible in the long run)?
There is no easy answer to that question. We’re essentially dealing with a situation of maximization of utility on a piecewise function where half of the variables are unknown and the other half are highly subjective. So, let’s look at it piece by piece —
In normal life, a person’s enjoyment of their life over time produces a utility value. In general, we might expect that a basic utility curve would look something like this:
Here, the enjoyment out of life is generally fairly high until later in life. (Now, I realize that this is probably a rather cynically drawn graph, but I’m not alone in this sort of assessment, with Dr. Ezekiel Emanuel, brother of politician Rahm and noted bioethicist, catching some flack from the public media for a similar graph published in a paper he co-authored describing how to best allocate rare medical treatments in order to provide the greatest number of enjoyed life-years to the populace. I’m guessing politics came into play on this one, in that the concept of quality-adjusted life years has been around for years, and serves as the basis for the Emanuel paper. In any regard…) After age 70 or so, with bodily decline and the increasing percentage of deaths of friends and loved ones, the joy taken from life tends to decrease. (I am reminded of this recently, in that, in visiting aging relatives over the past few days, ALL of them have told me, in the same words, even, “Getting old is hell, Dave. Don’t get old if you can avoid it.” My response to this was to then point out that getting old is way better than the alternative state, but this, in more than one way, tended to fall on deaf ears….) The utility of your life, then, is represented by the space under the curve, which can be gotten by summing utility over time.
Averaging across people, life, even in its decline, still provides positive utility — that is, it is still worth living. In some cases of drawn out terminal illness, the utility of continuing to live may become negative. At this point, continued living actually detracts from the aggregate utility accumulated during the lifetime, at which point discussions of euthanasia may start to enter the picture.
Now, what makes choosing a “best time” to be frozen so difficult is that you have to try and estimate what the future utility will be of a post-cryonics suspension life. In the best case scenario, the utility of a future life will be higher than what you left in the past. If, for example, you are a video-game enthusiast, the video-games of the far future are likely to be many times more complex and immersive than today’s games, so you might be enthralled to live in the future, whereas now you are merely content. If this is the case, then you would want to be frozen as early as possible, minimally in your prime.
If life expectancy has gone up in the future, as well, then you are especially well off in turning in your present chips early.
However, this is the best case scenario. In the case of the future dystopia, you may find that, though your life expectancy is longer, every day is barely livable, causing you to think back fondly on the times and people you traded in for this misery.
Or, you might suffer terribly from the cryonics process, leaving you a barely functioning vegetable. In that case, utility might be hard to estimate, but will probably be pretty low.
Of course, then there’s the distinct possibility that you might not be able to be brought back at all…
… in which case you fouled up, cheating yourself of the life you could have lived in the present. (Sucks, don’ it?)
What might also be the case, however, is that the future is not all that different from the present, with the possible exception of a longer life-span. In this case, you are merely drawing out your decline.
In my opinion, this option is the most likely, especially considering the number of people who look back fondly on the halcyon days of their youth. Sure, the comfort and excitement of the present are great, but people tend to claim that they were happier back in the good old days when they were young. (I’m not actually convinced that the past was quantitatively happier, but, then, I’m not an anthropologist, historian, or sociologist.) In any regard, in terms of preservation, barring some sort of brain-rejuvenation procedure that would reverse some of the negative symptoms of aging that could be applied after your thawing (unlikely, in my opinion, but then again… so is being brought back to life from a near-dead state in cryonic suspension), it would seem that the best time to put your faith in the future would be before or just about at the onset of senility. My initial reasoning for this is that we are, as human beings, defined by our memories and by our ability to form new memories. Our memories are what, in large part, separate the human experience from that of other animals.
In support of this claim (which is, in itself, not terribly novel), consider a cat. Researchers over the last few decades have noted that in tasks involving tests of feline memory span, house cats (Felis silvestris catus) tend to do do worse after 5 seconds, and fall to near chance by 30 seconds. For an overview, see Fiset & Doré (2005). (But c.f. Goulet (1996).) This means that a cat would seem to live its life in short 30 second windows, acting largely out of momentary desire, leading to the capricious tendencies which render the animal so adorable. In comparison, consider an aged human being whose memory is pretty well degraded. (Many of us have had personal contact with such a relative, but for those who haven’t, consider some famous cases such as Henry Molaison or Clive Wearing.) To say that we are our memories is never so clear as when observing a person whose memory is damaged or degraded. Out of these persons, we are likely to hear the same stories over and over again as the moods that provoke such recall shift, themselves partially modulated by current experience and environment. At the extreme end of memory decline, the appearance of a relative or companion may be greeted with great excitement, even if that person had just stepped out of the room a moment prior. We become, without our memories, much like the animals — merely a set of biological states, falling back into the same states again and again — operating, like the cat, on caprice. It is only with our memories that we are able to sew together the events of the day, to make sense of our surroundings, to indulge in and appreciate complex systems like language or music or motion pictures. To be able to fully enjoy the future, then, it would be optimal to go into stasis while the memory is still fit, perhaps as early as age 60 or 70.
However, again remembering that resuscitation from cryonic preservation is at best uncertain, then we are forced to arrive at a different conclusion — cashing in one’s chips early deprives us all late-life utility. Thus, it would seem optimal to get the most enjoyment we can out of present life and push back preservation until as late as possible.
Amusingly, this leaves us exactly where we are with the current system: wait until legal death has set in, and then have yourself cryo-preserved. This maximizes the “sure-bet” utility, and, if resuscitation will ever be possible, then you will have also earned yourself a few more years.
This also means that, if, in your autumn years, you are finding yourself senile, then it’s probably best to forgo the preservation, give the money that you would have spent on it to your kids or to charity, and die knowing you made the best of what you had.
As a life-long champion of cryonic preservation as a way of seeing the future, it almost pains me to admit that in most cases, it’s really not worth it to be frozen. But, I guess, when it comes down to it, why should you trade in today for tomorrow unless there is a sure net gain in utility? It would seem, rather, that the old wisdom holds true — go with what you know. Keep on Keepin’ on.