A more interesting question would be why software programs, or databases, age and die. At some point, their own size and complexity will make them hard to change, and they will be left to slowly die.
When I was younger, I wanted to live forever. But now I came to believe that dying is actually good, for a similar reasons. As we age and learn, we become experts at many things, but at the cost of flexibility and speed of learning (this is actually expressed in myelin coating of synapses). So we need to have next generation of people starting from scratch, questioning everything, otherwise we would be stuck with the old ways of doing things.
So perhaps aging and death is an evolutionary adaptation, to changing conditions in our environment.
I'm selfish enough, but I'm not sure how enjoyable it would be once I reach 130, not to mention 1300, on the theory that even if much of the physical aging problem is solved, much of the mental aging problem will remain, and the same things making me increasingly mentally inflexible will make it all increasingly less fun.
I also think death is treated too seriously by people believing they're just a bunch of atoms but still thinking of themselves as an entity meaningfully separate from the rest of the world.
We have had successful cryonic restoration of brain tissue in rabbits? I believe, and have also had successful brain transplants of mice.
I easily figure in the next 100 years we will accept cloning as a replacement for death. Simply duplicate the body, and transfer the brain, maybe throw in some extra gray matter to replenish what is lost through aging. Of course "throw in some extra gray matter" sells the complexity a bit short, but we are definitely on track to accomplish it.
I anticipate never having a 130 year old body. I would just replace mine with a genetically enhanced one at 60, and start over from ~15 (or honestly whatever the earliest age to insert a brain is). Almost anyone should be able to raise the money in ~30 years to pay to have another clone grown.
And from there you can iterate a few generations on first generation tech until we can manipulate the living brain into being able to learn like you are five again, hopefully without the negative side effects present in current brains of that capacity.
> in the next 100 years we will accept cloning as a replacement for death. Simply duplicate the body, and transfer the brain
Cloning isn't the same thing as "Simply duplicat[ing] the body."
Cloning creates an embryo which turns into a human infant.
Then you have to wait 18 years for it to mature before you can transfer the brain.
There's an insurmountable moral barrier to raising a fully conscious child to adulthood and then killing it so you can have its body.
Some commenters down-thread have suggested removing the infant's brain and raising it, without consciousness, in a vat of some sort.
Aside from the obvious difficulty and huge expense of maintaining a fantastical life-supporting "vat" for 18 years, it just simply wouldn't work.
Human beings require social interaction, and consciousness, to survive. An infant deprived of social interaction and environmental stimulation, and the consciousness to experience it obviously, would die. Animals also require physical interaction; our bones and muscles and senses can't develop properly in a vat, so you'd end up with, at best, a pathetic excuse for a body, totally unable to function in any way you'd enjoy, if your clone survived at all (which it wouldn't).
In short, this idea is both morally appalling and biologically ridiculous.
>The human body does not literally require social interaction to continue operating. That's just silly.
I wasn't talking about you. I was talking about whether a human infant missing most of its brain and deprived of all social interaction, environmental stimulation, and physical activity would thrive and mature normally. It would not.
(Also, just for the record, there are things which aren't possible to do, no matter how many awesome engineers you have.)
I can't imagine why you would need a cloned body. With the level of technology needed to make that work, you should just be able to rejuvenate the one you already have. The body is already self-repairing, the problem is that the aging process makes this mechanism faulty. That can be fixed. If your cells can easily grow and multiply from a zygote into a mature adult, there's no reason you can't fix the flaws which prevent total rejuvenation. It might require nanites though. But that still sounds easier than a brain transplant and then manipulating the brain to learn like a 5yo again.
The later is surely science fiction, but brain transplants - which really, are just figuring out how to perfectly reconnect spinal tissue, which while incredibly hard is not something completely fictional since we have already done it in very reduced test cases (and we know that stem cells are likely going go give us an easy way eventually to just regrow the gaps in the spinal column) are not nearly as far out as nanites of the sophistication to modify organic cells are right now.
What about the ethical issue of clones? Will clones be raised in vats without ever achieving consciousness?
If you have to raise your clone by yourself as another human being, who's to say which one of you deserves to keep living?
It all sounds so very nice in theory, but the reality might be that only the very rich and the elite will be able to afford to undergo such procedures, mainly because of the secrecy needed to essentially grow sacrificial human beings to maturity.
Well, preferably you wouldn't be growing conscious clones. Ideally, you'd sabotage the brain's development so as to prevent consciousness from developing in the first place (keep the hindbrain, chuck the rest so to speak) or come up with a way to artificially control vital functions.
But don't worry. There are lots of other ethical concerns to focus on after you get rid of the conscious clone problem.
"Well, preferably you wouldn't be growing conscious clones. Ideally, you'd sabotage the brain's development so as to prevent consciousness from developing in the first place"
Arguably, if you're at that level of sophisticated biological manipulation, you're probably better-off simply growing the organs/replacement-parts/cells by themselves.
Read a SF novel recently [0] where the rejuvenation treatment that you take periodically to extend your life indefinitely also makes you sterile temporarily. If you chose to have children (which is socially frowned upon), you must stop taking the treatment forever.
Not sure that we would be able to implement such a rationale solution, but at least it was pretty logical. The novel is essentially about the other grim decisions you have to take to have a constant population.
[0] This was in a book with multiple short stories from Paolo Bacigalupi. I believe this is Pump Six and Other Stories. Most of the novel are rather pessimistic, but at the same times sounds plausible enough to happen. I also recommend The Wind Up Girl from the same author.
"Society might need death, but I still want to live forever."
This occurs in cell populations - the programmed self-death of cells (apoptosis) becomes corrupted and the individual cell acts selfishly (relative to the organism) and stays alive.
We have a word for this phenomenon and that word is "cancer".
I enjoyed this metaphor even though it's a bit misleading.
Suspension of apoptosis is necessary, but not sufficient, for cancer. We have plenty of non-cancerous cells that rarely or never undergo apoptosis such as neurons or stem.
The implication that immortality = cancer does not follow.
"The implication that immortality = cancer does not follow."
Indeed, cellular immortality may be cancer when it gets against apoptosis and it's just a natural thing when not. Cancer as well comprises a wider range of anomalous cellular developments that most often does not turn off the apoptosis. The metaphor however was about selfishness, on individual organism and cell level.
>> Society might need death, but I still want to live forever.
I've never understood people who say they'd like to live forever. It just doesn't make any sense to me. The oddest thing is to listen to someone who talks about how it is - not probably or hopefully - going to happen in their lifetime. I once had an acquaintance who spoke of it so seriously that it was religious; he honestly believed (possibly still does) that he will not die.
You have the ones who are so absolutely terrified of death that they desperately grip onto the concept of immortality; a science fiction replacement for an afterlife or reincarnation they do not believe in. (Tangent: Why do so many people reject the idea of open casket funerals. Death is just too horrible to even observe, let alone having to reconcile that it will one day happen to them? "Think of the children" is a common argument, which is bullshit; perhaps such a large number of adults are so fearful exactly because they were never exposed to it.)
You have people who use the idea as a fantasy that someday they will do all the things they want to do, but don't have the time, money, or motivation to do today. This category is depressing, because I don't understand how someone can believe that an extended future would magically fix whatever is holding them back right now.
Then there are those who treat our species like a special little snowflake in the universe. That somehow being sentient with a consciousness is intrinsically deserving of cheating death - self-righteousness at the species level. That science can solve any problem, and not only will it be possible, but that it unequivocally should be done. "I think, therefore I am, and should forever be".
tldr; Death is, at least presently, inevitable. Get over it.
I'm not afraid death. I wish to see, participate in, and develop the (if possible, far) future.
And yeah, I dream of the day I could do more far reaching stuff than what I do to pay the rent.
I see 2 pragmatic reasons for aging: enabling faster biological evolution, and escaping the lower performance/plasticity of older brain. We are at the brink of usefully being able to engineer human DNA and germ line. Once we get there (possibly not in my lifetime) - to the extent brain plasticity/performance can be kept up (and improved) - I see little reason for death through aging.
Society might need death, but I still want to live forever.
Anyone who is sufficiently math literate should know that they're very unlikely to live forever. If there's some finite chance you're going to die each year, as you consider longer theoretical lifespans, the probability you'll die gets so close to 1, it's basically a certainty. Anyone who is sufficiently science literate should know that thermodynamics and the heat death of the universe precludes anyone living forever.
All that said, if you offered me a life-span boost to 250, 1000, or a million years, I'd take it!
I think that once all the people of my generation are dead, and all the people I can relate to, who had the same formative experiences I had are gone, I won't want to live much longer.
I think even if we engineer away death, you will still have the psychological structure from the "formative years" -- adolescence to early adulthood-- that sort of fundamentally make you personality-wise.
The songs and movies that gave you emotional experiences, the events that happened, etc. For me and my cohort it would be groups like Nirvana, Pearl Jam, Beck, and movies like Reality Bites and Pulp Fiction. These were the things that spoke to us as we were becoming adults.
It's not that those groups or movies mean much to me nowadays, but I feel that, socially, I am a peer with someone who lived through those years at the same age I did. It's not simply that we share the same cultural references, nor is it just that we happen to be the same age. I think rather that we were formed by the same events at that age and time.
If I live to be 230, I might feel somewhat disconnected from a 200-year-old, even as the age difference becomes relatively smaller and smaller, because that offset of 30 years made for a completely different formative experience. I'd still want to be friends with people who _get_ me.
My grandpa lived into his 90s. It got to the point where the children of his peers were dying. His main thing to do was read the obits and note how he knew that person. He had lots of family and friends, but no one could relate to his stories of old sports games, WWII, etc. etc. He was in good health and will mentally alert, but after my grandma died, it was just a matter of time. He died of a blood infection, no illness or anything.
So even if we can undo aging and death, we still might need to address the developmental process-- tweak it in some direction. Either have eternal formation, or re-formations-- something.
Maybe you can have it both ways. There is a good chance we live in some form of a multiverse and our experience depends on self locating uncertainty. The effect of this is big world immortality; we each live forever from our own perspective. There isn't scientific consensus on this yet, but my research and the simple logic behind it has convinced me enough to take it into account in my planning.
I'm probably getting this wrong since I haven't looked into it, but I think they're talking about the idea of an infinite number of universes that contain the totality of all that is possible. When one dies, they only cease to exist in that universe, but continue to exist in others.
I think it's fine if some people get to live as long as they want. Not all of us desire it and not all of us would make good use of it. The people that do it can then decide to stop whatever is helping them stay alive when they no longer want to. I see no downsides to this.
This is idealistic in the extreme. I think it could be easily argued that for our own sake and that of the environment we live in, humans could use more natural attrition, not less.
If we get to a point where large portions of our population are no longer oppressed or in poverty, where horrendous wars are largely a thing of the past, and we are already managing our population and environment in a healthy way -- then I'll be in your camp but right now we're doing exactly none of those things so, uh, no way getting rid of death is a good idea IMO.
What's your evidence that more attrition will create a greater society? If anything, greater longevity of people would allow for the accrual of more knowledge and wisdom. Living longer gives you a better long-term perspective. Give people a direct reason to care about what the environment will be like 150 years from now and maybe they'll care more about the CO2 they're putting out.
but right now
None of this is right now. We're right at the infancy of genetic manipulation. Even with the accelerating rate of technology growth, we won't understand our biology at a genetic level enough to be able to manipulate it in an everyday way for at least 50 to 150 years.
"So we need to have next generation of people starting from scratch, questioning everything, otherwise we would be stuck with the old ways of doing things."
This is a very important concept - and one I would like to help illustrate with a thought experiment:
Think of the most liberal, progressive thinker[1] you can from the 19th century. I don't know ... Karl Marx ? Tolstoy ? Lincoln ? Whomever ...
Now, hold that thought ... and think of the most reactionary, "conservative", bigoted, old-fashioned public figure you can ... Mike Huckabee, perhaps ?
I will now suggest that Mike Huckabee, in almost every imaginable measure, is more progressive and liberal than (whomever you chose in step one). Mike Huckabees wife has worn pants. Mike Huckabee has spoken to a divorced woman in public. Mike Huckabee has probably used birth control.[2]
See how fast that happened ? In less than 200 years, the political window has shifted far enough that the most reactionary, right wing member in 2016 is more liberal and more progressive than the most liberal and progressive figures from the prior period.
How will that work if people from 200 (or 300 or 400) years ago are not only still around, but presumably well funded with vast stores of capital ?
[1] let's limit it to very well known, universally recognized figures...
[2] Ok, I'm not sure about that one, but you get the point ...
The neoreactionaries flip it the other way; they would shove this thought experiment in the faces of "conservatives" and say, "Haven't you, by any reasonable measure, failed utterly and completely in achieving any of your political goals? Do you have any reason to believe this will change in the future?"
The evolution of aging is an arms race to the bottom. Very few species can succeed without aging once any competitors evolve aging, and this happened very early on. Here is thinking on "we age because the world changes." Of course what is great for evolutionary success has nothing to do with what is great for the individual, and the two should not be confused.
"Understanding why we age is a long-lived open problem in evolutionary biology. Aging is prejudicial to the individual and evolutionary forces should prevent it, but many species show signs of senescence as individuals age. Here, I will propose a model for aging based on assumptions that are compatible with evolutionary theory: i) competition is between individuals; ii) there is some degree of locality, so quite often competition will between parents and their progeny; iii) optimal conditions are not stationary, mutation helps each species to keep competitive. When conditions change, a senescent species can drive immortal competitors to extinction. This counter-intuitive result arises from the pruning caused by the death of elder individuals. When there is change and mutation, each generation is slightly better adapted to the new conditions, but some older individuals survive by random chance. Senescence can eliminate those from the genetic pool. Even though individual selection forces always win over group selection ones, it is not exactly the individual that is selected, but its lineage. While senescence damages the individuals and has an evolutionary cost, it has a benefit of its own. It allows each lineage to adapt faster to changing conditions. We age because the world changes."
Why would survival of older individuals be in any way detrimental to the species' success? In the absence of aging, organisms living longer simply means that they are still sufficiently-well adapted to the environment. When the environment changes beyond what they can adapt to, they die off and (hopefully at least parts of) the new(er) generation will carry on.
Because we are social creatures and there are still limited resources. Older generations have outsized influence on the tribe based on their experience which can drag the rest down.
For a contemporary example, consider the real estate bubble. When the bubble burst and everyone realized how badly the banks had screwed up, what happened? Well, everyone who owned a home worried about losing its value. The banks took some stock off the market to hide it, and all the leadership up to the president vowed to do everything possible to "maintain real estate values", even though the "value" was predicated on sub-prime mortgages that people couldn't actually afford.
In this way, the older generation whose experience is tied to a particular environment exerts its influence in a way that damages the younger population. Being young and inexperienced means being adaptable but naive and inefficient, being old and wise means knowing how things work and a vested interest in keeping them that way.
Speculating - older individuals take resources and even if they were continuing to reproduce advancement comes through successive generations of genetic mixing. It's probably advantageous for the species if an individual has a child (mixing up genetic code) and then that child has children while the parent dies.
Otherwise you might have less biodiversity which may make the species less adaptable overtime (and maybe lose to another species with aging).
Immortality has a specific meaning here, which is that risk of death due to intrinsic causes does not increase over time. This is distinct from negligible senescence, which is more a case of few manifestations of aging until very late life.
Immortality is also observed for flies in late life (http://discovermagazine.com/2001/may/breakdialogue). They have a very high mortality rate at that point, but it doesn't increase further over time. That doesn't seem to be the case for humans, though, based on the very sparse data for people at extreme old age.
A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.
This is a non-trivial benefit of mortality. Not just in science, but in politics too. Wouldn't it be horrible if, oh, Genghis Kahn was still alive and in charge? Death may limit the good that some people do, but it limits the bad that people do, too, and roughly speaking it seems to be worth the trade-off. Even the most ruthless dictator of the most powerful, untouchable empire will eventually fall to entropy.
(One of the reasons _1984_ is such a nightmare was not it's cruelty and horror, but it's all-too-believable stability, even with human mortality. Orwell's appendix gives a ray of hope, however, when he discusses the fact that human language itself would, in the long run, prevent even that world from continuing indefinitely.)
> but it's all-too-believable stability, even with human mortality. Orwell's appendix gives a ray of hope, however, when he discusses the fact that human language itself would, in the long run, prevent even that world from continuing indefinitely.
This a probably true as a matter of status quo, but it is not necessitated by anything. Science advances because it is designed to advance. It just advances faster when social power cycles regularly.
One of Heinlein's books plays with this concept. There's a Martian race that are essentially immortal, at least from natural causes. Every 40-50 years they go through a change and become childlike for 5 years. Lack of awareness, playfulness, no interest in sex, and an emotional state that changes quickly. It's explained that it's how they are able to rejuvenate themselves.
Or better yet engineer a more efficient replacement for the central nervous system. 100 years in the future at increasing rates of technological development, it seems very likely that we could engineer a substance that could interface with the brain to augment it and eventually replace it seemlessly with no jarring loss of consciousness.
This also a reply to similar comment about "cleaning myelin".
The big question here is (to which I allude in my comment): How do you control the "resetting" process, so that you wouldn't lose the information that you consider important? I simply don't think there is a good way to do it.
We already have a way to be immortal - have kids and teach them what you know and think is important. Which is an arduous and complicated process; I don't think this "myelin cleaning" or whatever will be any easier.
I don't think I want this reset. It may mean you become entirely different person, or your memories get lost. Let's say you and your wife resets, and forget most memories you have of each other, pretty much why you're together. Or you reset and you become a different person to your kids, and they become different to you.
I personally find either having kids, or teaching (if you can't have kids for whatever reason), a more interesting proposition than some magical procedure that will clean my brain. If anything, it sounds really irresponsible to your future self - kinda like leaving your kids in the forest to take care of themselves.
> I don't think I want this reset. It may mean you become entirely different person, or your memories get lost. Let's say you and your wife resets, and forget most memories you have of each other, pretty much why you're together. Or you reset and you become a different person to your kids, and they become different to you.
This already exists in the forms of psychedelic drugs and transcranial magnetic stimulation. There is no memory loss, you just start thinking and feeling about things differently. It can and does lead to divorce and changes in relationships to relatives: http://well.blogs.nytimes.com/2016/03/18/an-experimental-aut...
This is not at all the downside you portray it to be. Many people use these methods to change or leave dysfunctional relationships.
The person you are right now will be dead in 20 years. In its place will be a person who has access to some of your more important memories as well as the resources you have made available for it. After a long enough period of time, the difference between wiping your own brain and starting over vs having children will be small.
Or unless retirement is legally enforced, voids voting rights and lasts forever, so people past a certain age are prevented from having any influence (except to the extent that they can persuade other people using their wisdom and experience).
Quite how that'd work economically though, I have no idea.
"Aging" is what costs you flexibility and speed. If you reverse aging, you'll maintain your flexibility and speed.
Moreover, aren't you assuming that we couldn't possibly manage loss of flexibility? Even if most people are inflexible because they've aged, this doesn't prohibit them from having a base level of flexibility and thus find a workaround for whatever limitation you're imagining this imposes.
I think they are different topics under different environment. Software changes, a lot, over time. You can hardly recognize a software's source code if you don't touch them for a decade. The features changed, new features added, old features deprecated, etc. On the other hand, over the life time of a person, their DNA will not be changed dramatically. What their cells need to do is just an exactly copy of its genes. There won't be a case where one person needs to grow a third arm, while in software world, we constantly change requirements.
Software evolves more like the evolution of a species: Small changes over time to adapt the ever changing environment.
>we become experts at many things, but at the cost of flexibility and speed of learning
It's partly because you are an expert at a unique combination of many things that you have great irreplaceable value. This is threatened by aging diseases even before you die.
Also I don't think that more knowledge makes it harder to learn.
This would be true if knowledge was purely about breadth. However it's really about explanatory depth, and depth ultimately wins. For instance, your mind has formed many connections between those aforementioned different fields of expertise, and some of these ideas reach into yet more fields.
yeah, if dying wasn't a thing anymore, we would need to at the very least boost the brain plasticity of everyone by quite a lot, or we would be facing a complete stop in the progress of societal values. We would still have slaves probably, for exemple, and racism would be much crazier.
The article explains that different organisms exhibit different patterns of aging, when we consider aging as either defined by increases in the probability of death, or decreases in the probability of reproduction.
Taken together with the evolution of species, this implies a plasticity in both the mechanisms and utility of aging - something which is otherwise considered to be a rather solid constant of life.
The takeaway then is that we must 1) widen our definition of aging to accommodate the variety of natural phenomena, and 2) reconsider the intuition that a specific pattern of aging, such as the one found in humans, is necessary for the survival of the organism and/or the species.
I'm a little troubled by the argument that an increase in the probability of death signifies or is equivalent to an increase in the rate of aging. I feel like that conclusion doesn't follow and is misleading, but I'm not sure. Am I off base?
If we suppose humans live to around 85 years on average, and rarely if ever die before 65, then there's a big bell curve normal distribution on 85, and what looks like a non-linear exponentially increasing probability of death up to about 80. But that doesn't mean everyone started aging faster at 65, it just means people started dying around 65.
Imagine that you go bowling and throw 20 mph balls on average. The distribution would look similar. Bell curve on a pin dropping at around (say) 5 seconds, but the curve starts at around 4 seconds and ends at 6ish. Does this mean the ball suddenly accelerated at the end? No, in fact the opposite happened, it was slowing down. But the rate of probability that a pin goes down is exponentially increasing from 0-5 seconds.
Not a perfect analogy to aging by any stretch, but am I right that an increase in the probability of death is unrelated to aging - the speed at which we approach death?
If we suppose humans live to around 85 years on average,
and rarely if ever die before 65, then there's a big bell
curve normal distribution on 85, and what looks like a
non-linear exponentially increasing probability of death
up to about 80.
You're suggesting that the probability of dying after 85 decreases. That's not the case, it continues to rise. If it decreased that would suggest an improvement in health (un-aging) at 85, which doesn't occur.
Having an average at some point doesn't mean there's a bell curve around it. The average of a uniform distribution [0-100] may be 50, but there's no bell curve around 50. It's just a uniform distribution all the way through.
You misunderstood me and confused the probability of dying by 85 with the probability of dying at 85. You're talking about the cumulative distribution and I was talking about the probability distribution.
The chance of death at a given age is a bell curve.
The chance that I'll die at 150 years old is zero, it is less than the chance that I'll die at age 70. The chance that I'll die by the time I'm 150 is 100%.
The chance of death at a given age oughtn't be a bell curve. The chance of me (33) dying at 60 are much higher than the chance of my coworker (65) dying at 60. There's a shear drop off at the age in question. After that point you have 0 chance of dying at the particular age, it's not a bell curve.
So I feel like I still don't understand what you're getting at in your example.
Do you want to understand? I'll try to help, but it seems like I'm using math terminology and concepts you're not familiar with, and I don't want to presume you're interested in learning math.
Sadly, we're not even talking about the meat of my point, you got stuck on the uncontroversial preface to my real point. My point was that Nautilus is wrong and maybe being sneaky by saying that aging accelerates near the end of life because the probability of dying is going up. That's not true, and the bowling analogy shows why.
Over time, the probability of pins being knocked over goes up. But you can't conclude that the bowling ball is accelerating. The author made an incorrect conclusion from the data to make his point. It might be intentionally misleading, or it might be a mistake, but it's nonetheless incorrect to suggest that an increase in the probability of death must have been caused by an increase in the rate of aging.
I'm not saying that the PDF of death by age should be a bell curve, I'm stating a fact. It already is a bell curve. Go look at the data. You're trying to argue against reality with logic. You're right, it doesn't have to be a bell curve. But it IS a bell curve.
Very few people die of old age at 55. Many people die of old age at 80. Very few people die of old age at 100, because there are very few people left. That's a bell curve. Does that make more sense?
Half way through the article the author starts to confuse 'aging' and 'dying'. I would argue both are inevitable, we all age and we all die but not at a constant rate. Isn't that what inevitable means?
The author defined aging in terms of the probability of death. I found this definition helpful rather than confusing. You noted that we age and die at a constant rate; how would you define aging if not in terms of the probability of death?
There are some problems with the definition. Humans have very high relative probability of death during their first five years, but this quickly declines and then starts to rise again. This means that humans "age" backwards for the first part of their life, which is not particularly intuitive or helpful. However, the definition is helpful in the context of understanding how our aging compares to aging in other animals.
I would imagine that the folk definition of aging is more closely align to your body improving itself vs declining/plateauing.
For the first 1/3 - 1/2 of our lives our bodies are building themselves up through growth, but then you hit middle age-ish, hang up the football cleats, and start caring more about your health because "you're not a teenager anymore".
The premise that aging is defined as the probability of death feels artificial, or at least out of line with typical understandings of the word.
I think the folk definition of aging is actually aligns quite closely with the probability of death definition.
Consider the phrase "He looks like he aged 20 years, but it has only been 5 years since I last saw him." Everybody understands this to mean that he looks like his health has declined in 5 years the way most people's health would decline in 20 years.
If you replace "health has declined" with "probability of death has increased", then it means roughly the same thing.
It is true that the folk understanding of "health has declined" could be based on several proxies such as skin texture, baldness, etc. I think what the probability of death definition does is bring some precision to what you mean when you say "health has declined".
If you limit your examples to health declines/old age, then - yes. My point is that the term "aging" doesn't always relate to the old and infirm.
When my three-year-old nephew ages ten years I would hardly agree that means he's more likely to die, just the opposite. A thirteen-year-old is significantly more fit for survival.
The purpose of the definition is not to evaluate individual aging, but the aging of populations. The probability of death neatly summarizes all the risks that the population experiences at different ages. Although the probability for a single person is difficult to measure, and can vary wildly with varying behaviour, the probability is easy to measure at the population level. By summarizing over the whole population, you can see the risks that are common to all humans, rather than just particular populations.
So smokers or people who jump from planes may not be older compared to those who don't. We don't have a single, reliable instrument that can measure individual level aging.
The author is somewhat confusing aging and dying. Aging is a mechanism. It is there for (probably) many reasons. One of them is to protect against cancer, and therefore from dying. You either age or you get cancer.
"Aging" might have evolved in part because of cancer, but that does not mean that aging is the best solution to cancer. It's just a method of dealing with it, which might be totally subpar. Evolution never leads to best-case scenario, it leads to good-enough scenario. Saying "either you age or get cancer" is just... not correct.
If we find a way to not age and not get cancer, then we have (presumably) evolved.
>That is not true. It could lead to the most optimal solution.
There is no such thing as "the most optimal solution". Optimality is a human imposition on the world. Fitness functions do not actually exist, they are merely a way for us to conceive of the operation of selection. Evolution is not performing gradient descent.
This sort of adaptivism has got to go. First of all, nothing is there for any reason; it just is. Evolution is an ad hoc process where things happen because they need to, and they happen based on expediency. There are many facets of life that escape adaptive constraint - selection has a limited reach.
This comment supposes that aging protects cells against cancer; I think this presumption is based on the antitumor properties of telomeres, which impose the 'Hayflick limit' on cellular division.
It is presumed by humans that this mechanism may have some adaptive role in tumor suppression. However: this is not why it appeared (all eukaryotes have telomeres, even unicellular ones), so any antitumor properties are an ancillary benefit.
It is incorrect to assume it impute reason to evolution. It seems highly likely that aging rests close to the border of selective influence, and it is highly presumptive to imagine it is governed by consequence.
This is not a presumption I made. This is believed by many scientists. Telomeres are just part of the story. There are many other reasons[1,2,3]. The third link is not a paper so very readable.
The cell has many ways to combat oncogenesis and when these protections fail, it tries to go into senescence (SIGTERM) or die(SIGKILL).
Nanobots that would replace damaged cells with new non-cancerous ones are not yet here.
I'm a cancer biologist, so I appreciate the relation to oncogenesis. But you said "It is there for (probably) many reasons". This is what I am contending; aging is simply there, because that is what happened. 'Reason' is a judgment we apply, and it's important to appreciate that much of what exists is not driven by anything we might call "reason". I do not believe that the collection of phenomenon we call "aging" is uniformly the product of adaptive consequence. Notably, we die in part because evolution simply doesn't care, or isn't able, to keep us alive indefinitely.
It's important to note that aging is not so much a mechanism to protect against cancer as it is a method to avoid cancer (that is, by dying before cancer develops).
The cell dies or stops working as effectively as before and is potentially replaced by other cells, but the organism lives. So overall, the cell's DNA is more likely to be transmitted.
If the cell lived (selfishly), it could take down the whole organism with it and not reproduce.
They are much the same thing in many discussions of aging. The generally agreed upon definition of aging in the geroscience community is that it is an increase in risk of death due to intrinsic causes. You are more aged if you have a higher risk of death, and you are aging if your risk of death due to intrinsic causes is higher today than it was yesterday.
Then we can get into primary aging (think of the SENS list of damage, internal mechanisms like mitochondrial damage and cross-link deposition) versus secondary aging (think of smoking and getting fat, things that increase the pace of damage accumulation), and further complexities after that. But the core definition of aging is very simple, and it is all about dying.
Coming from the biochem community (I'm not a scientist and was just a tech there + grad school classes), aging in the labs I worked in was seen as more of a mechanism. Sure, it leads to deterioration of cellular function which inevitably leads to death.
However, aging!=dying since aging can protect the whole organism (as opposed to individual cells) from dying and some would argue that it is there primarily to protect the organism from dying from cancer and for healthy reproduction.
What?! Please don't call cell senescence "aging". Our cells do destroy themselves and replenish from stem cells but the accumulated damage called "aging" causes cancer.
If you age, you get cancer, eventually. Sometimes some other pathology gets you first but everyone is afflicted with every "aging disease" but we seem to only care about which one kills you first.
Senescence (/sɪˈnɛsəns/) (from Latin: senescere, meaning "to grow old," from senex) or biological aging (also spelled biological ageing).
One of the reasons cells age is to not get cancer. The cells that age can still get cancer! And probably more likely to get cancer than young cells. But less likely than if they didn't go into senescence at all.
>"From the perspective of natural selection, once you’re no longer able to reproduce, you might as well be dead."
Both today's article and yesterdays said something to this effect, which is blatantly wrong. A now-infertile parent affects the survivability of their offspring, possibly positively or negatively. Since their offspring share their genetics, the parent thus is still involved in the natural selection process.
I'll note that the authors here favor programmed aging, a vocal minority in the research community at the moment. This has a number of varieties, but essentially boils down to the root cause of aging is considered to be epigenetic changes. So epigenetic changes -> damage.
The majority view in the research community is vice versa, that damage -> epigenetic changes. Aging is an accumulation of cell and tissue damage, something that spirals down ever faster as the damage starts to cause damage repair systems to fail. The forms of fundamental damage that cause aging are actually well agreed upon, but there is a lot of argumentation over which are more important and how exactly they cause specific age-related conditions.
How can a field sustain two such diametrically opposed sets of theory? Because while we know the differences between old and young tissue, we still don't have a full accounting of cellular metabolism, and certainly don't have a full map of how a->b->c for all molecular biology at any given time, let alone over the entire course of aging sufficent to explain from start to finish any specific age-related condition.
This is why SENS ("repair the damage, don't try to understand why it causes age-related disease, just fix it and things will become clear one way or another") is so important. We can repair the damage. That is much, much easier and cheaper than trying to understand the full chain of cause and effect.
The next five to ten years should see one or other side proven conclusively wrong. The challenge is that addressing secondary effects in aging can still produce benefits. The water is muddy.
On the damage viewpoint, we have things like senescent cell clearance now under development in companies like Oisin Biotechnologies and UNITY Biotechnology. Clearance extends life in mice. Senescent cells are known to contribute to many age-related diseases.
On the epigenetic alteration side we have things like restoration of youthful GDF11 levels, which improves health in mice by signaling stem cells to go back to work. From the damage viewpoint, those stem cells are in decline as a reaction to damage, and the signaling therapy is an override. From the programmed aging point of view the signaling change is the primary cause.
I think that the most compelling argument against programmed aging and for damage is that some forms of damage cannot be repaired by our biochemistry. Specifically persistent glucosepane cross-links in the extracellular matrix, for example, causing loss of structural properties such as elasticity. Also some of the constituents of liposfusin that builds up in long-lived cells and causes their lysosomes to malfunction. It doesn't matter how youthful your epigenetic patters are, you cannot break them down.
Any possible news on how to isolate glucosepane so we could even get started? Last time I checked, there were no solution that wouldn't also dissolve the surrounding cells.
Essentially the few people working on this are still looking for drug candidates, largely based on mining the bacterial world for suitable enzymes to use as a basis. They have bacteria that consume glucosepane, so that's a starting point.
I prefer the SENS approach where the assumption is that different types of damage accumulate, but that there are ways to improve the cells machinery to repair or improve the problems.
> The way this graph [of surviving population size over age] has been constructed, a straight line going diagonally downward is neutral, or no aging at all.
Um, no. They introduced age as probability of dying within that context. Therefore a constant age would produce a population size that shrinks exponentially, but never reaches the zero line, just like with radioactive isotopes' constant decay rate.
It kind of fits with Kurzweil's guess that in 15 years or so we'll be extending life expectancy faster than we age. Though he's big into the nanobots idea which I'm skeptical of. But with advances in AI and DNA sequencing I can see people figuring out which bits of DNA do what and being able to modify the aging process.
I'm not so sure this is how brains work. I get the impression both from what I've read and uh... personal operation.. that the resolution of memories fades with time/disuse which likely makes "space" for new information. Brains have a very high plasticity. You might say well if you forget what you once knew are you still you. I'd argue you go through this several times already in our relatively short current lifespan. Are you the same guy at 35 as you were in your early 20s? I'm sure not.
Mine seems to do a halfway-decent job of emptying obsolete data automatically. It's much more adaptable than a PC that goes into a kernel panic when the hard drive fills and it can't swap anymore.
However, right now my brain can't remember where I left my wallet, and it's stuck on a loop remembering some stupid kids song, so you may have a point.
In any case, the remembered parts of a millennium may not be complete, but that would be better than a still-incomplete memory of a century.
Computer analogies aside, I think that the longevity community (perhaps justifiably) is ignoring some really critical aspects of aging and dying.
In the same way as relatively new diseases such as cancer and heart disease have confounded the progress of medicine upon finally mastering the treatment/prevention of infectious disease, what new maladies await us when we "defeat" those and start living well past 100? What does the psychological health of a 100++ year old even look like? Will we _really_ want to live that long, and if so, who dies to make room for the living?
> Then we'll have to choose: do we want newborn babies or really old people?
That's the interesting question isn't it? And _who_ gets the privilege to answer?
I have no idea to what extent we'll defeat aging and extend life. However, it is reasonable to expect that we'll at least manage to go far enough that concerns about population will enter the picture as well as much more strange problems that have never existed but which should be considered.
Since when are cancer and heart disease relatively new? They've been around for as long as people have, just most people didn't live long enough to get them for other reasons.
By "new" I mean that only relatively recently in human history (in the last ~100 years) have people been able to live long enough that these become health problems of concern. Before the 20th century, most folks just got sick as a result of an infection of some kind and died.
All I am saying is that there will be other new problems that are uncovered as we continue to extend human life-span.
It's not like our brain is filling up and then we hit some point where it's full. If you ask me about something that happened a few weeks ago, I'm going to barely remember any details. Our brain is constantly flushing out old memories to make new ones.
If life is a dice, even the biological immortal throw it every time they climb into a car. In the long run, every methusalem is bed ridden, when statistics catch up to him/her.
even in the most optimistic of views, we're all dying some time before the heat death, that's for sure, unless we alter the laws of physics or move to an other universe
PS: Consider, if people are having kids at 12-15, then at 100 someone might be your great, great, great, great, great, grandparent. Why they must be 200 ;0
When I was younger, I wanted to live forever. But now I came to believe that dying is actually good, for a similar reasons. As we age and learn, we become experts at many things, but at the cost of flexibility and speed of learning (this is actually expressed in myelin coating of synapses). So we need to have next generation of people starting from scratch, questioning everything, otherwise we would be stuck with the old ways of doing things.
So perhaps aging and death is an evolutionary adaptation, to changing conditions in our environment.