6 ms·

The article addresses Gompertz' law: the probability of dying in any given year increases exponentially with age (older people have ever higher death rates). T

The article addresses Gompertz' law: the probability of dying in any given year increases exponentially with age (older people have ever higher death rates). This is an EMPIRICAL FACT. As you live longer, this probability accumulates exponentially, so the probability of being alive falls super-exponentially: p(being alive) = aexp(-exp(bt)). I'm pretty sure there ain't nothing you can do about this. Why not? Because evolution built it pretty strongly into our genes. Here's how I see it: if an organism arose which had this "death gene" turned off, it would not adapt to sudden changes in the environment. It might be susceptible to a novel infectious agent which wipes out the whole species. Thus evolution tends to weed out immortal or very long-lived organisms. Don't forget how natural selection works. It's not single creatures that adapt; it's about whole species. The only way for a species to adapt is for some of its individuals to die and be replaced by their offspring which differ genetically from their parents. Evolution needs death to work. Hence death is built-in. Look at this scary graph (with a logarithmic y axis!): https://en.wikipedia.org/wiki/Gompertz%E2%80%93Makeham_law_of_mortality#/media/File:USGompertzCurve.svg https://en.wikipedia.org/wiki/Gompertz%E2%80%93Makeham_law_o... and then tell me that medical advances will do anything to make you live to 200. Go on, I dare ya.

alejohausner 11y ago
This also gets me thinking about pesticides in apples, of all things. I read Michael Pollan's "The Botany of Desire" a while ago, and was really struck by the story of Johnny Appleseed. For those of you who didn't grow up in the USA, he travelled through the country planting apple seeds, so that later settlers would find whole apple orchards in place when they moved in. The interesting thing is that apples don't "spring true" from seed. In other words, an tree that bears sweet apples will almost certainly have seeds that lack the gene for sweetness. Apple trees grown from seed will certainly bear crab apples. They are sour, and are only good for fermenting and making alcoholic apple cider. Settlers were certainly happy to have crab apples, because cider is fun and easy to make. But they certainly didn't eat those apples. If you want sweet apples, you have to use grafting: if you are lucky enough to get a tree with sweet apples, you will probably immortalize it, but taking cuttings from its branches, and grafting them onto ordinary crab-apple root stock. The part of the tree above ground will be genetically different from the part below. If the root stock nears death, you'll take cuttings from the part above ground and graft them onto new roots. This is all very nice, but it sidesteps evolution: you've created an immortal organism, which won't be able to fight off insects, fungus, and bacteria that attack apples, and which are constantly evolving to overcome a plant's defenses. Since the tree can't generate new chemicals that kill or repel these attackers, humans have to invent fungicides and insecticides to do it for them. That's why apple farming relies so heavily on spraying scary chemicals on the trees. Any war you declare on time and change is a war you will lose.
dorgo 11y ago
My theory about evolution and aging is that evolution just doesnt care about individuals after they created offspring. There is no advantage for an individual (or a species) to live longer than to create offspring. Hence evolution never cared to optimize us for a longer life.
- GFK_of_xmaspast 11y ago
  Didn't your grandparents ever baby-sit you.
  - darkmighty 11y ago
    Baby-sitting and also verbal/demonstrative knowledge before written language was a thing.
- secabeen 11y ago
  There's something to that, but it doesn't explain menopause in women. If reproduction is the end-all-be-all, why not evolve the ability to reproduce throughout the natural lifespan. See the Grandmother Hypothesis for a possible explanation: https://en.wikipedia.org/wiki/Grandmother_hypothesis https://en.wikipedia.org/wiki/Grandmother_hypothesis
  - alejohausner 11y ago
    Humans are different from other primates, in this respect. For example, chimpanzees don't have menopause: female chimps continue to give birth until death. Elephants too. And Galapagos tortoises, I think. This fact argues against the theory that "nature just wants you to reproduce and then die". Why do chimps (and many other species) keep on reproducing in old age? Why are human women different?
    - dorgo 11y ago
      >Why are human women different? Some mutation in early histroy maybe? Evolution never cared to fix it, because it happens later in life and most woman are done with reproducing at this point in life. >"nature just wants you to reproduce and then die" No. Nature just wants you to reproduce. Wheter you die afterward doesnt matter.
Symmetry 11y ago
I'm not sure that makes any sense. If there are sudden changes in the environment then the less fit animals will die off without any need for a death gene. If there aren't any changes in the environment then there's no need for animals to die off. Evolution works just fine with prokaryotes which don't really get old in the sense that we do. Also technology allows us to do many things that aren't allowed for by our evolution, like flying to the Moon. Evolution isn't an all-powerful force but something that works strictly through variation and selection. If we find the physical process that cause aging and how to stop them then there's nothing evolution can do to stop us.
- alejohausner 11y ago
  Granted, sudden changes to the environment would kill off the less fit individuals. So I'll change my argument a bit: Suppose you've overcome infant mortality, and have also solved the problem of adult mortality, so all subsequent people are immortal. Suppose moreover that young adults insist on having more than zero children (that's likely to continue, you'll agree). Now you've got a population that won't stop growing. Resources are finite, and there will be mass starvation. What are your options in such a scenario? Should you kill off old people, kill off young people, or prevent all future babies? Suppose you prevent all future babies. Then you end up with no more sex, no more genetic variability, and now the whole species might be susceptible to a sudden environmental change. So my argument is that old people must die to make room for genetically-different young people. Without natural death, there will be less room for evolutionary adaptation.
  - Symmetry 11y ago
    The question you're asking there is one of human morality and politics rather than evolution or technological feasibility. I'll tell you what solution evolution "wants" to pick: population increase, starvation, and may the fittest win. Obviously that's not something you or I would want but it's why evolution doesn't have any problem with creatures living indefinitely.
    - deleted 11y ago
logfromblammo 11y ago
Medical advances will make me live to 200 by replacing some of my body's stem cells once every 20 years, followed by additional critical advances during my "borrowed time". Modeling past behavior is not going to accurately predict future behavior. The model suggests that older people are steadily losing some quantity of a finite resource that acts as a protectant against otherwise fatal conditions. Replenishing that resource would therefore allow some people to move backwards on the age-mortality curve, effectively transforming the super-exponential curve into an exponential curve. That would make your probability of living to 160 years after your treatments begin around 90%, rather than an iota more than 0% (assuming average 1/1500 annual mortality rate). That gives you a lot more time to find and eliminate the individual risk factors which contribute to various causes of mortality. Recent research has found very old individuals whose entire red blood supply is likely to be derived from a single hematopoietic stem cell. Other research has demonstrated regular transfusions of whole blood from younger donors into older recipients as improving specific age-related health conditions. (See also [0],[1].) That old sci-fi trope about people cloning themselves for the spare parts will eventually become reality, except the clones will be harvested at 18 days old from an artificial growth medium instead of after 16 years in a secret island facility. Some nations will ban the practice under political pressure from religions, and it will just move to the black market. What's really going to close the door on clinical immortality is economics and politics, not medical science. [0] http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4021776/ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4021776/ [1] http://www.nature.com/nri/journal/v13/n5/full/nri3433.html http://www.nature.com/nri/journal/v13/n5/full/nri3433.html
reasonattlm 11y ago
Aging is caused by damage accumulation. There are very good ways to model how that works, see for example reliability theory [1]. There is little difference at this level of modeling between a human and a car. It is just a complex system of redundant components subject to breakage. If you repair it well it enough it has an indefinite mean time to failure. The important thing to appreciate about medicine is that no present medicine does anything to repair damage. All advances in medicine and related technologies relevant to control over disease that have led to longer lives across the board have only modestly slowed accumulation of damage. Slowing damage accumulation more deliberately or via engineering metabolism is very hard and the best of approaches can't beat the outcomes of exercise or calorie restriction, they aren't moving the needle any further. I don't expect them to, either. Fortunately, there is the alternative approach of repair, with the outcome of indefinite healthy life spans for sufficiently comprehensive repair. The future is one in which the root cause damage is periodically repaired. Lines of research related to SENS for example, such as senescent cell clearance. Other than some forms of stem cell replacement, there are no implementations of damage repair today, but that will change very rapidly once things get going. [1]: https://en.wikipedia.org/wiki/Reliability_theory_of_aging_and_longevity https://en.wikipedia.org/wiki/Reliability_theory_of_aging_an...
- sliverstorm 11y ago
  Aging is caused by the accumulation of damage, but damage accumulates because your repair systems stop working as well (for reasons I don't really know). As even just a very simple example, an adult takes longer to heal from cuts, scrapes, bruises and breaks than a young child.
quizzas 11y ago
Wonderful argument by the way. But the fly in the ointment here is the following analogies: 1. Human evolution never meant for man to fly, but human ingenuity figured out a way to circumvent these biologic limitations. 2. Man was never meant to go faster than 20MPH in a sprint, but here we are regularly traveling 80MPH on freeways. Similarly, your argument holds true until man's ingenuity circumvents these limitations, such as transposing mental/emotional state onto a cybernetic machine that can be indefinitely updated/fixed for as long as the materials are available to do so. We may not be there now, but in 100 years?
xlm1717 11y ago
I wouldn't put a limit on human ingenuity to overcome this problem. Evolution has already become a tool for humanity to further itself. See: Farming. It will only come under greater human control as genetic engineering continues developing. Maybe one day, we will be able to turn this "death gene" off. What happens then? If a novel infectious disease pops up, sure it will cause widespread death, but it's highly unlikely it will cause the death of the species. We'll either save a few of us in some deep underground bunker, or we'll figure out how to beat it. That's really the only Earth-based threat that can still threaten the species as a whole. Evolution operates on a scale of decades and centuries. Human ingenuity operates on much shorter time scales. We don't fall under natural selection anymore. We are the ones who select now. We don't need some of us to die for us to adapt. We can adapt to every single biome and environmental condition on Earth without waiting for genetic variation to produce individuals who can. Evolution may need death to work, but we no longer need evolution for us to work.
- dummy7953 11y ago
  I don't think extra longevity is economically viable. I mean, it was a gigantic tooth-pulling process to pass health care reform. At some point it just becomes too expensive to remain alive.
- jfoutz 11y ago
  The ebola vaccine was developed ridiculously quickly. Compared to 20 years ago, it's practically magical. Yeah, There is probably something worse than spanish flu in our future. We may not survive, but our odds so much better off now. I think our most serious earth based threat is us. Nuclear war, engineered diseases, or (imho most likely) destruction of the environment.
summerdown2 11y ago
The thing is, technological advances can be exponential, too. Moore's law is one example, but there are others. Here's a quote from Ray Kurzweil, who's a leading exponent of this idea: > "People declared the Human Genome Project a failure halfway through, when one percent had been decoded -- they said it'd take 700 years. My reaction was, no, we're almost done. It was finished seven years later." Personally, I think Kurzweil is an optimist and I suspect it'll be too late for most of us, but we are just beginning to learn to rewire our genes. Take a look at this link, and notice how many significant events happened in the last fifteen years: https://en.wikipedia.org/wiki/Gene_therapy#History https://en.wikipedia.org/wiki/Gene_therapy#History Now, imagine that level of change accelerating, because we're still in the early days.
happyscrappy 11y ago
Wow, if you survive birth you don't have that level of risk until your almost sixty? Can that be right?
- alejohausner 11y ago
  Yep. So, enjoy yourself and ignore death until you reach retirement age. Then, keep looking over your shoulder to see if the grim reaper is catching up on you.
  - happyscrappy 11y ago
    Thanks. I still can't stop thinking about death though.
BjoernKW 11y ago
As Steve Jobs eloquently put it in his Stanford commencement speech: "Death is very likely the single best invention of Life. It is Life's change agent." In my opinion this not just applies to the species as whole but to individuals, too: Old people tend to become set in their ways. It's not overpopulation but this very issue that's the most evident problem with extreme longevity or immortality: As soon as a significant amount of people will be able to live forever, change and human development will likely cease to exist in the long run. Perhaps this can be delayed by not just rejuvenating the body but at the same time also preventing the biochemical processes that lead to fossilization of thinking but in the end this might be unavoidable and ultimately lead to the extinction of the human race due to sheer boredom.
- alejohausner 11y ago
  Then again, maybe Jobs' view of death was colored by knowing he had pancreatic cancer. It might have made him more fatalistic. Also, can it be said that the older Steve was more set in his ways than when he was younger? His example argues against characterizing old people in that way. Mind you, he's just one data point.
  - BjoernKW 11y ago
    Perhaps he wasn't in a way that would've kept him from innovating our industry but there's a thin line between knowing your purpose and becoming single-minded to the extent that you become stubborn and don't accept criticism or new ideas anymore. Steve Jobs showed some signs of that later in his life. Besides, 56 certainly isn't old age, especially nowadays and even more so when your daily activity involves thinking about new product ideas that have the potential to change the world.
    - alejohausner 11y ago
      I see your point. I was kind of equivocating "being set in one's ways" with "being uncreative". Jobs was certainly single-minded throughout his life. In a way, he was set in his ways from an early age, at least in that sense.
saurik 11y ago
...and yet there are things that last both ludicrously longer than us and things that seem to be theoretically capable of lasting forever but in practice fail anyway by eventually screwing up and either damaging itself beyond repair or getting dismantled by another organism. It is not clear that planned obsolescence is a necessary trait everything must have to achieve market domination, even when considering a defensive strategy for a potential disruptive competitor.
AndrewKemendo 11y ago
The unstated assumption here is that the evolutionary process is good for humanity in the long run. I would argue that is not the case, as in the long run there will be some event that puts humanity at existential risk. Better then to self direct our own evolution to something that is more robust. I find these discussions funny because so many of the tech crowd are big advocates of terraforming mars or some other such "insurance" for humanity's survival - yet very few say, instead of keeping the fragile human as the future model, lets change the model and transform what was human biology into something more durable. That's not to say we have the answer as to how to do that, but it's at least a better eon level goal.
scythe 11y ago
>I'm pretty sure there ain't nothing you can do about this. Why not? Because evolution built it pretty strongly into our genes. Here's how I see it: if an organism arose which had this "death gene" turned off, it would not adapt to sudden changes in the environment. It might be susceptible to a novel infectious agent which wipes out the whole species. Thus evolution tends to weed out immortal or very long-lived organisms. Your prediction is right, but you've expressed the conclusion wrong: thus long-lived organisms are unlikely to persist, i.e. removing a single "death gene" only allows you to experience one of the many other forms of death. The species is never at risk because any potential cause of death is always present. I believe that the current hypothesis is essentially that evolution does not need you around longer than it takes to produce and raise healthy offspring, and furthermore, it does not need you to reproduce beyond prime years when your offspring are likely to be healthiest. So genes having these effects are not selected for; furthermore because most genes have side-effects (e.g. sickle-cell anemia), they are likely selected against. >Look at this scary graph (with a logarithmic y axis!): >https://en.wikipedia.org/wiki/Gompertz%E2%80%93Makeham_law_o.. https://en.wikipedia.org/wiki/Gompertz%E2%80%93Makeham_law_o.... >and then tell me that medical advances will do anything to make you live to 200 I wouldn't be surprised if we reach 150. "Medical advances" is a broadly-defined category. Indefinite extension is rather unlikely in the foreseeable future, though.
- alejohausner 11y ago
  > removing a single "death gene" only allows you to experience one of the many other forms of death I see your point. On the other hand, why are there so many ways to die when you grow old? If one form of death doesn't get you, whey are there so many built-in mechanisms for death, in each of us? Why does your body betray you without fail, eventually? Why do mayflies die so young, just after they reproduce? Perhaps evolution has no need of them after they reproduce, but that's not how it looks like to me, in the case of mayflies. It is one thing to say that there is no advantage to living after reproduction, and another to say that you MUST die after reproduction. It is perfectly conceivable to imagine post-reproductive mayflies surviving for many years. Heck, post-reproductive humans survive again as long after the end of fertility. > Indefinite extension is rather unlikely in the foreseeable future, though I agree with you there. That was pretty much my point all along. And I was trying to put forth a rational argument for WHY I think that, but I can't come up with a totally convincing explanation.
eevilspock 11y ago
I think this Quora answer says what you're saying, arguing that "the human lifespan [is] not a limit but an optimization":http://qr.ae/L5v6z http://qr.ae/L5v6z
- Animats 11y ago
  That's much closer to reality. Death is mostly a timeout, not a wearout, and this has evolutionary benefits. Medicine has made great progress on wearout and damage problems, but hasn't yet made much progress on the timeout issues, the ones which degrade the self-repair mechanisms over time. This will probably be solved eventually, although it may only work for new organisms created from genetically engineered DNA. Bear in mind how new our understanding of how life works really is. The role of DNA wasn't understood at all until 1953. DNA manipulation is still at the "hack and see what works" level; designing and editing DNA from first principles is not yet here.
Buttons840 11y ago
> Evolution needs death to work. Wouldn't it be, "evolution needs birth to work"? Death only helps evolution insomuch as it helps birth. Death often does help birth because old genes aren't hanging around using up all the resources and preventing the birth of new genes.
maratd 11y ago
> Evolution needs death to work. Hence death is built-in. Yes, but life duration is an equation. The main component of that equation is parasite load. > Here's how I see it: if an organism arose which had this "death gene" turned off, it would not adapt to sudden changes in the environment. It's not about sudden changes. Those almost never happen. It's about the Red Queen. https://en.wikipedia.org/wiki/Red_Queen_hypothesis https://en.wikipedia.org/wiki/Red_Queen_hypothesis Parasites are constantly shuffling their genes, so we must as well, to resist them. So going back to our equation ... life duration is directly correlated to parasite load. Tons of viruses/bacteria/etc. trying to kill you, death gene tweaks the lifespan into the low numbers to decrease the duration between variation to adapt to the parasites. Almost no parasites? You live for thousands of years. And there are creatures on this planet that do. They have few/no predators or parasites that ail them. Want to increase humanity's life span? Kill off all the parasites. Your death gene will adapt over time and increase the lifespan.
- ringwalt 11y ago
  Wouldn't parasites be a constant factor in the death rate? How do you explain an exponentially rising death rate? The "criminals" in the article's example are more like mutations or other damage that builds up in cells, which increase the death rate exponentially as your body's ability to catch them falls linearly over time. If you have bacteria in your bloodstream you're already in septic shock, infections can't explain, say, heart disease or most types of cancer.
  - maratd 11y ago
    > Wouldn't parasites be a constant factor in the death rate? How do you explain an exponentially rising death rate? I don't think the death gene works that way. It doesn't just turn on and poof! you're dead at the exact time specified. More like a factor that controls average life span, which would result in an exponentially rising death rate. Recent research suggests it's something in the blood. http://www.theguardian.com/science/2015/aug/04/can-we-reverse-ageing-process-young-blood-older-people http://www.theguardian.com/science/2015/aug/04/can-we-revers... > If you have bacteria in your bloodstream you're already in septic shock, infections can't explain, say, heart disease or most types of cancer. Those disorders may be caused by parasites, we simply don't know. But even if they aren't ... they simply wouldn't be a part of the equation. I'm not saying this "death gene" determines lifespan absolutely. It determines it on average. Other shit can still go wrong. Like a lion might eat you.
Houshalter 11y ago
This is a bullshit "just-so story". In the wild most animals die long before they reach their age limit. There isn't enough selection pressure for evolution to spend resources to prolong life. Evolution doesn't work on whole species. Or even individuals. It works on genes. If there is a gene that prolongs the life of an animal by 10 years, and it has 1.5x more babies in that time, then that gene will spread itself 1.5x more than the alternative genes. It doesn't matter if it's detrimental to the species in the long run. Lots of genes are. Sure evolution needs death to work, but that's a very different claim than saying it selects for death. It's certainly possible to defeat aging. There are a number of animals that don't age at all: https://en.wikipedia.org/wiki/Negligible_senescence https://en.wikipedia.org/wiki/Negligible_senescence Medical advances could definitely make you live to 200. We are very close to the ability to grow organs, and eventually entire bodies. Even if your body ages, you could just replace it. That would extend your life a ton on it's own. Add new brain tissue over time as the old stuff dies, and rejuvenate it a bunch with young blood (which has been shown to improve old brains a lot.) Or you could get cryopreserved and wait until the really distant future, when have nanotechnology and gene editing and who knows what.
- outofcuriosity 11y ago
  I apologize for the disillusionment that will follow: 1) Negligible senescence occurs mostly in organisms radically-different from humans and we have no idea how to edit those pathways into humans or if those pathways actually hold any value to humans. Hydra cells still die but the organism itself doesn't age. If you want to apply a gene-level anti-senescence therapy to an organism, you have to transfect the traits correctly into every cell of the organism--trillions of opportunities for catastrophic failure. 2) Gene editing probably has downstream cascades that we can't foresee. 3) Organ transplants become more risky with age, and the mortality risk from anesthesia does as well. If you were to replace your body, your brain would necessarily be the same age--and since we can't fix the (conjectured) senescence pathways in a living organism, you'd eventually be a senile individual in a young body. There's some neuroregenerative therapies that hold promise, but any "regenerative cell therapy" could also be read as "may create proliferative tumors" 4) Cryopreservation of a living organism is assumed to kill it, or at least alter it radically enough that its original functions will never be restored. Reconstructive nanotechnology is probably impossible due to heat dissipation and brownian motion--you'd have to hope that somehow a human scientist figures out how to engineer a new class of cell that is capable of navigating and repairing all extant human cells, which is more-or-less Clarke's Law. We are not here forever. Oxygen metabolism literally rusts our bodies over time, disrupting and destroying countless pathways. Aging and death was part of the mitochondrial bargain. Tortoises have been evolving against the bargain's drawbacks for longer than humans have been around, and they still aren't immortal.
rue 11y ago
> Thus evolution tends to weed out immortal or very long-lived organisms. […] Evolution needs death to work. Hence death is built-in. The description of a process in the past that we refer to as evolution could be argued to have benefited from death. Mutation happens anyway. Offspring happens anyway. It does not require death. You could say that death is good because it frees resources for the younger generations—but there is a hidden assumption there: that at some point, there has been some preceding form that did have a vastly longer lifespan and it was less viable because of that. In reality, we have evolved from very, very short-lived organisms, and the trend has been upwards as benefits of those long-surviving members (wisdom, experience, etc. beyond merely bearing offspring) have given an advantage to the survival of species. … However, none of that is actually necessary for the evolution of a species in the sense of a mechanism that reacts or proacts to environmental changes—it can just as well be artificial.
colin_mccabe 11y ago
I think you are misunderstanding how natural selection works. You seem to be implying that there is some guiding hand behind the evolution of each species. In fact, if longer life were an advantage for an individual member of any species, the gene pool would gradually shift towards longer life. Some species do indeed have extremely long lives-- some trees live for thousands of years, and some whales and turtles can live and even reproduce for more than a hundred years. Instead, life length is a tradeoff that is made at the individual level. A longer life means more opportunities to reproduce (or help your offspring), but it also means that you have to set a higher limit for the number of divisions each cell can make, which can decrease cancer resistance. A slower metabolism will produce fewer harmful byproducts, but give you less energy than a fast-burning metabolism. And so on. Longer life makes more sense for more intelligent organisms, since they can be more effective when they're older due to what they have learned. Often, they need teach the young, which can have relatively long gestation times. But an organism's lifespan is always going to be oriented around its reproductive cycle. With all that being said, humans are very clever and I wouldn't be surprised if ways were found around human mortality eventually. I can't help thinking of all the "humans were never meant to fly" arguments that people used to pooh-pooh heavier than air flight in the old days. There's no fundamental reason why life extension couldn't be done except time and effort. But I am not as optimistic as Kurzweil about the timeframe (who is?)

alejohausner 11y ago

This also gets me thinking about pesticides in apples, of all things. I read Michael Pollan's "The Botany of Desire" a while ago, and was really struck by the story of Johnny Appleseed. For those of you who didn't grow up in the USA, he travelled through the country planting apple seeds, so that later settlers would find whole apple orchards in place when they moved in. The interesting thing is that apples don't "spring true" from seed. In other words, an tree that bears sweet apples will almost certainly have seeds that lack the gene for sweetness. Apple trees grown from seed will certainly bear crab apples. They are sour, and are only good for fermenting and making alcoholic apple cider. Settlers were certainly happy to have crab apples, because cider is fun and easy to make. But they certainly didn't eat those apples. If you want sweet apples, you have to use grafting: if you are lucky enough to get a tree with sweet apples, you will probably immortalize it, but taking cuttings from its branches, and grafting them onto ordinary crab-apple root stock. The part of the tree above ground will be genetically different from the part below. If the root stock nears death, you'll take cuttings from the part above ground and graft them onto new roots. This is all very nice, but it sidesteps evolution: you've created an immortal organism, which won't be able to fight off insects, fungus, and bacteria that attack apples, and which are constantly evolving to overcome a plant's defenses. Since the tree can't generate new chemicals that kill or repel these attackers, humans have to invent fungicides and insecticides to do it for them. That's why apple farming relies so heavily on spraying scary chemicals on the trees. Any war you declare on time and change is a war you will lose.

dorgo 11y ago

My theory about evolution and aging is that evolution just doesnt care about individuals after they created offspring. There is no advantage for an individual (or a species) to live longer than to create offspring. Hence evolution never cared to optimize us for a longer life.

GFK_of_xmaspast 11y ago
Didn't your grandparents ever baby-sit you.
- darkmighty 11y ago
  Baby-sitting and also verbal/demonstrative knowledge before written language was a thing.
secabeen 11y ago
There's something to that, but it doesn't explain menopause in women. If reproduction is the end-all-be-all, why not evolve the ability to reproduce throughout the natural lifespan. See the Grandmother Hypothesis for a possible explanation: https://en.wikipedia.org/wiki/Grandmother_hypothesis https://en.wikipedia.org/wiki/Grandmother_hypothesis
- alejohausner 11y ago
  Humans are different from other primates, in this respect. For example, chimpanzees don't have menopause: female chimps continue to give birth until death. Elephants too. And Galapagos tortoises, I think. This fact argues against the theory that "nature just wants you to reproduce and then die". Why do chimps (and many other species) keep on reproducing in old age? Why are human women different?
  - dorgo 11y ago
    >Why are human women different? Some mutation in early histroy maybe? Evolution never cared to fix it, because it happens later in life and most woman are done with reproducing at this point in life. >"nature just wants you to reproduce and then die" No. Nature just wants you to reproduce. Wheter you die afterward doesnt matter.

Symmetry 11y ago

I'm not sure that makes any sense. If there are sudden changes in the environment then the less fit animals will die off without any need for a death gene. If there aren't any changes in the environment then there's no need for animals to die off. Evolution works just fine with prokaryotes which don't really get old in the sense that we do. Also technology allows us to do many things that aren't allowed for by our evolution, like flying to the Moon. Evolution isn't an all-powerful force but something that works strictly through variation and selection. If we find the physical process that cause aging and how to stop them then there's nothing evolution can do to stop us.

alejohausner 11y ago
Granted, sudden changes to the environment would kill off the less fit individuals. So I'll change my argument a bit: Suppose you've overcome infant mortality, and have also solved the problem of adult mortality, so all subsequent people are immortal. Suppose moreover that young adults insist on having more than zero children (that's likely to continue, you'll agree). Now you've got a population that won't stop growing. Resources are finite, and there will be mass starvation. What are your options in such a scenario? Should you kill off old people, kill off young people, or prevent all future babies? Suppose you prevent all future babies. Then you end up with no more sex, no more genetic variability, and now the whole species might be susceptible to a sudden environmental change. So my argument is that old people must die to make room for genetically-different young people. Without natural death, there will be less room for evolutionary adaptation.
- Symmetry 11y ago
  The question you're asking there is one of human morality and politics rather than evolution or technological feasibility. I'll tell you what solution evolution "wants" to pick: population increase, starvation, and may the fittest win. Obviously that's not something you or I would want but it's why evolution doesn't have any problem with creatures living indefinitely.
  - deleted 11y ago

logfromblammo 11y ago

Medical advances will make me live to 200 by replacing some of my body's stem cells once every 20 years, followed by additional critical advances during my "borrowed time". Modeling past behavior is not going to accurately predict future behavior. The model suggests that older people are steadily losing some quantity of a finite resource that acts as a protectant against otherwise fatal conditions. Replenishing that resource would therefore allow some people to move backwards on the age-mortality curve, effectively transforming the super-exponential curve into an exponential curve. That would make your probability of living to 160 years after your treatments begin around 90%, rather than an iota more than 0% (assuming average 1/1500 annual mortality rate). That gives you a lot more time to find and eliminate the individual risk factors which contribute to various causes of mortality. Recent research has found very old individuals whose entire red blood supply is likely to be derived from a single hematopoietic stem cell. Other research has demonstrated regular transfusions of whole blood from younger donors into older recipients as improving specific age-related health conditions. (See also [0],[1].) That old sci-fi trope about people cloning themselves for the spare parts will eventually become reality, except the clones will be harvested at 18 days old from an artificial growth medium instead of after 16 years in a secret island facility. Some nations will ban the practice under political pressure from religions, and it will just move to the black market. What's really going to close the door on clinical immortality is economics and politics, not medical science. [0] http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4021776/ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4021776/ [1] http://www.nature.com/nri/journal/v13/n5/full/nri3433.html http://www.nature.com/nri/journal/v13/n5/full/nri3433.html

reasonattlm 11y ago

Aging is caused by damage accumulation. There are very good ways to model how that works, see for example reliability theory [1]. There is little difference at this level of modeling between a human and a car. It is just a complex system of redundant components subject to breakage. If you repair it well it enough it has an indefinite mean time to failure. The important thing to appreciate about medicine is that no present medicine does anything to repair damage. All advances in medicine and related technologies relevant to control over disease that have led to longer lives across the board have only modestly slowed accumulation of damage. Slowing damage accumulation more deliberately or via engineering metabolism is very hard and the best of approaches can't beat the outcomes of exercise or calorie restriction, they aren't moving the needle any further. I don't expect them to, either. Fortunately, there is the alternative approach of repair, with the outcome of indefinite healthy life spans for sufficiently comprehensive repair. The future is one in which the root cause damage is periodically repaired. Lines of research related to SENS for example, such as senescent cell clearance. Other than some forms of stem cell replacement, there are no implementations of damage repair today, but that will change very rapidly once things get going. [1]: https://en.wikipedia.org/wiki/Reliability_theory_of_aging_and_longevity https://en.wikipedia.org/wiki/Reliability_theory_of_aging_an...

sliverstorm 11y ago
Aging is caused by the accumulation of damage, but damage accumulates because your repair systems stop working as well (for reasons I don't really know). As even just a very simple example, an adult takes longer to heal from cuts, scrapes, bruises and breaks than a young child.

quizzas 11y ago

Wonderful argument by the way. But the fly in the ointment here is the following analogies: 1. Human evolution never meant for man to fly, but human ingenuity figured out a way to circumvent these biologic limitations. 2. Man was never meant to go faster than 20MPH in a sprint, but here we are regularly traveling 80MPH on freeways. Similarly, your argument holds true until man's ingenuity circumvents these limitations, such as transposing mental/emotional state onto a cybernetic machine that can be indefinitely updated/fixed for as long as the materials are available to do so. We may not be there now, but in 100 years?

xlm1717 11y ago

I wouldn't put a limit on human ingenuity to overcome this problem. Evolution has already become a tool for humanity to further itself. See: Farming. It will only come under greater human control as genetic engineering continues developing. Maybe one day, we will be able to turn this "death gene" off. What happens then? If a novel infectious disease pops up, sure it will cause widespread death, but it's highly unlikely it will cause the death of the species. We'll either save a few of us in some deep underground bunker, or we'll figure out how to beat it. That's really the only Earth-based threat that can still threaten the species as a whole. Evolution operates on a scale of decades and centuries. Human ingenuity operates on much shorter time scales. We don't fall under natural selection anymore. We are the ones who select now. We don't need some of us to die for us to adapt. We can adapt to every single biome and environmental condition on Earth without waiting for genetic variation to produce individuals who can. Evolution may need death to work, but we no longer need evolution for us to work.

dummy7953 11y ago
I don't think extra longevity is economically viable. I mean, it was a gigantic tooth-pulling process to pass health care reform. At some point it just becomes too expensive to remain alive.
jfoutz 11y ago
The ebola vaccine was developed ridiculously quickly. Compared to 20 years ago, it's practically magical. Yeah, There is probably something worse than spanish flu in our future. We may not survive, but our odds so much better off now. I think our most serious earth based threat is us. Nuclear war, engineered diseases, or (imho most likely) destruction of the environment.

summerdown2 11y ago

The thing is, technological advances can be exponential, too. Moore's law is one example, but there are others. Here's a quote from Ray Kurzweil, who's a leading exponent of this idea: > "People declared the Human Genome Project a failure halfway through, when one percent had been decoded -- they said it'd take 700 years. My reaction was, no, we're almost done. It was finished seven years later." Personally, I think Kurzweil is an optimist and I suspect it'll be too late for most of us, but we are just beginning to learn to rewire our genes. Take a look at this link, and notice how many significant events happened in the last fifteen years: https://en.wikipedia.org/wiki/Gene_therapy#History https://en.wikipedia.org/wiki/Gene_therapy#History Now, imagine that level of change accelerating, because we're still in the early days.

happyscrappy 11y ago

Wow, if you survive birth you don't have that level of risk until your almost sixty? Can that be right?

alejohausner 11y ago
Yep. So, enjoy yourself and ignore death until you reach retirement age. Then, keep looking over your shoulder to see if the grim reaper is catching up on you.
- happyscrappy 11y ago
  Thanks. I still can't stop thinking about death though.

BjoernKW 11y ago

As Steve Jobs eloquently put it in his Stanford commencement speech: "Death is very likely the single best invention of Life. It is Life's change agent." In my opinion this not just applies to the species as whole but to individuals, too: Old people tend to become set in their ways. It's not overpopulation but this very issue that's the most evident problem with extreme longevity or immortality: As soon as a significant amount of people will be able to live forever, change and human development will likely cease to exist in the long run. Perhaps this can be delayed by not just rejuvenating the body but at the same time also preventing the biochemical processes that lead to fossilization of thinking but in the end this might be unavoidable and ultimately lead to the extinction of the human race due to sheer boredom.

alejohausner 11y ago
Then again, maybe Jobs' view of death was colored by knowing he had pancreatic cancer. It might have made him more fatalistic. Also, can it be said that the older Steve was more set in his ways than when he was younger? His example argues against characterizing old people in that way. Mind you, he's just one data point.
- BjoernKW 11y ago
  Perhaps he wasn't in a way that would've kept him from innovating our industry but there's a thin line between knowing your purpose and becoming single-minded to the extent that you become stubborn and don't accept criticism or new ideas anymore. Steve Jobs showed some signs of that later in his life. Besides, 56 certainly isn't old age, especially nowadays and even more so when your daily activity involves thinking about new product ideas that have the potential to change the world.
  - alejohausner 11y ago
    I see your point. I was kind of equivocating "being set in one's ways" with "being uncreative". Jobs was certainly single-minded throughout his life. In a way, he was set in his ways from an early age, at least in that sense.

saurik 11y ago

...and yet there are things that last both ludicrously longer than us and things that seem to be theoretically capable of lasting forever but in practice fail anyway by eventually screwing up and either damaging itself beyond repair or getting dismantled by another organism. It is not clear that planned obsolescence is a necessary trait everything must have to achieve market domination, even when considering a defensive strategy for a potential disruptive competitor.

AndrewKemendo 11y ago

The unstated assumption here is that the evolutionary process is good for humanity in the long run. I would argue that is not the case, as in the long run there will be some event that puts humanity at existential risk. Better then to self direct our own evolution to something that is more robust. I find these discussions funny because so many of the tech crowd are big advocates of terraforming mars or some other such "insurance" for humanity's survival - yet very few say, instead of keeping the fragile human as the future model, lets change the model and transform what was human biology into something more durable. That's not to say we have the answer as to how to do that, but it's at least a better eon level goal.

scythe 11y ago

>I'm pretty sure there ain't nothing you can do about this. Why not? Because evolution built it pretty strongly into our genes. Here's how I see it: if an organism arose which had this "death gene" turned off, it would not adapt to sudden changes in the environment. It might be susceptible to a novel infectious agent which wipes out the whole species. Thus evolution tends to weed out immortal or very long-lived organisms. Your prediction is right, but you've expressed the conclusion wrong: thus long-lived organisms are unlikely to persist, i.e. removing a single "death gene" only allows you to experience one of the many other forms of death. The species is never at risk because any potential cause of death is always present. I believe that the current hypothesis is essentially that evolution does not need you around longer than it takes to produce and raise healthy offspring, and furthermore, it does not need you to reproduce beyond prime years when your offspring are likely to be healthiest. So genes having these effects are not selected for; furthermore because most genes have side-effects (e.g. sickle-cell anemia), they are likely selected against. >Look at this scary graph (with a logarithmic y axis!): >https://en.wikipedia.org/wiki/Gompertz%E2%80%93Makeham_law_o.. https://en.wikipedia.org/wiki/Gompertz%E2%80%93Makeham_law_o.... >and then tell me that medical advances will do anything to make you live to 200 I wouldn't be surprised if we reach 150. "Medical advances" is a broadly-defined category. Indefinite extension is rather unlikely in the foreseeable future, though.

alejohausner 11y ago
> removing a single "death gene" only allows you to experience one of the many other forms of death I see your point. On the other hand, why are there so many ways to die when you grow old? If one form of death doesn't get you, whey are there so many built-in mechanisms for death, in each of us? Why does your body betray you without fail, eventually? Why do mayflies die so young, just after they reproduce? Perhaps evolution has no need of them after they reproduce, but that's not how it looks like to me, in the case of mayflies. It is one thing to say that there is no advantage to living after reproduction, and another to say that you MUST die after reproduction. It is perfectly conceivable to imagine post-reproductive mayflies surviving for many years. Heck, post-reproductive humans survive again as long after the end of fertility. > Indefinite extension is rather unlikely in the foreseeable future, though I agree with you there. That was pretty much my point all along. And I was trying to put forth a rational argument for WHY I think that, but I can't come up with a totally convincing explanation.

eevilspock 11y ago

I think this Quora answer says what you're saying, arguing that "the human lifespan [is] not a limit but an optimization":http://qr.ae/L5v6z http://qr.ae/L5v6z

Animats 11y ago
That's much closer to reality. Death is mostly a timeout, not a wearout, and this has evolutionary benefits. Medicine has made great progress on wearout and damage problems, but hasn't yet made much progress on the timeout issues, the ones which degrade the self-repair mechanisms over time. This will probably be solved eventually, although it may only work for new organisms created from genetically engineered DNA. Bear in mind how new our understanding of how life works really is. The role of DNA wasn't understood at all until 1953. DNA manipulation is still at the "hack and see what works" level; designing and editing DNA from first principles is not yet here.

Buttons840 11y ago

> Evolution needs death to work. Wouldn't it be, "evolution needs birth to work"? Death only helps evolution insomuch as it helps birth. Death often does help birth because old genes aren't hanging around using up all the resources and preventing the birth of new genes.

maratd 11y ago

> Evolution needs death to work. Hence death is built-in. Yes, but life duration is an equation. The main component of that equation is parasite load. > Here's how I see it: if an organism arose which had this "death gene" turned off, it would not adapt to sudden changes in the environment. It's not about sudden changes. Those almost never happen. It's about the Red Queen. https://en.wikipedia.org/wiki/Red_Queen_hypothesis https://en.wikipedia.org/wiki/Red_Queen_hypothesis Parasites are constantly shuffling their genes, so we must as well, to resist them. So going back to our equation ... life duration is directly correlated to parasite load. Tons of viruses/bacteria/etc. trying to kill you, death gene tweaks the lifespan into the low numbers to decrease the duration between variation to adapt to the parasites. Almost no parasites? You live for thousands of years. And there are creatures on this planet that do. They have few/no predators or parasites that ail them. Want to increase humanity's life span? Kill off all the parasites. Your death gene will adapt over time and increase the lifespan.

ringwalt 11y ago
Wouldn't parasites be a constant factor in the death rate? How do you explain an exponentially rising death rate? The "criminals" in the article's example are more like mutations or other damage that builds up in cells, which increase the death rate exponentially as your body's ability to catch them falls linearly over time. If you have bacteria in your bloodstream you're already in septic shock, infections can't explain, say, heart disease or most types of cancer.
- maratd 11y ago
  > Wouldn't parasites be a constant factor in the death rate? How do you explain an exponentially rising death rate? I don't think the death gene works that way. It doesn't just turn on and poof! you're dead at the exact time specified. More like a factor that controls average life span, which would result in an exponentially rising death rate. Recent research suggests it's something in the blood. http://www.theguardian.com/science/2015/aug/04/can-we-reverse-ageing-process-young-blood-older-people http://www.theguardian.com/science/2015/aug/04/can-we-revers... > If you have bacteria in your bloodstream you're already in septic shock, infections can't explain, say, heart disease or most types of cancer. Those disorders may be caused by parasites, we simply don't know. But even if they aren't ... they simply wouldn't be a part of the equation. I'm not saying this "death gene" determines lifespan absolutely. It determines it on average. Other shit can still go wrong. Like a lion might eat you.

Houshalter 11y ago

This is a bullshit "just-so story". In the wild most animals die long before they reach their age limit. There isn't enough selection pressure for evolution to spend resources to prolong life. Evolution doesn't work on whole species. Or even individuals. It works on genes. If there is a gene that prolongs the life of an animal by 10 years, and it has 1.5x more babies in that time, then that gene will spread itself 1.5x more than the alternative genes. It doesn't matter if it's detrimental to the species in the long run. Lots of genes are. Sure evolution needs death to work, but that's a very different claim than saying it selects for death. It's certainly possible to defeat aging. There are a number of animals that don't age at all: https://en.wikipedia.org/wiki/Negligible_senescence https://en.wikipedia.org/wiki/Negligible_senescence Medical advances could definitely make you live to 200. We are very close to the ability to grow organs, and eventually entire bodies. Even if your body ages, you could just replace it. That would extend your life a ton on it's own. Add new brain tissue over time as the old stuff dies, and rejuvenate it a bunch with young blood (which has been shown to improve old brains a lot.) Or you could get cryopreserved and wait until the really distant future, when have nanotechnology and gene editing and who knows what.

outofcuriosity 11y ago
I apologize for the disillusionment that will follow: 1) Negligible senescence occurs mostly in organisms radically-different from humans and we have no idea how to edit those pathways into humans or if those pathways actually hold any value to humans. Hydra cells still die but the organism itself doesn't age. If you want to apply a gene-level anti-senescence therapy to an organism, you have to transfect the traits correctly into every cell of the organism--trillions of opportunities for catastrophic failure. 2) Gene editing probably has downstream cascades that we can't foresee. 3) Organ transplants become more risky with age, and the mortality risk from anesthesia does as well. If you were to replace your body, your brain would necessarily be the same age--and since we can't fix the (conjectured) senescence pathways in a living organism, you'd eventually be a senile individual in a young body. There's some neuroregenerative therapies that hold promise, but any "regenerative cell therapy" could also be read as "may create proliferative tumors" 4) Cryopreservation of a living organism is assumed to kill it, or at least alter it radically enough that its original functions will never be restored. Reconstructive nanotechnology is probably impossible due to heat dissipation and brownian motion--you'd have to hope that somehow a human scientist figures out how to engineer a new class of cell that is capable of navigating and repairing all extant human cells, which is more-or-less Clarke's Law. We are not here forever. Oxygen metabolism literally rusts our bodies over time, disrupting and destroying countless pathways. Aging and death was part of the mitochondrial bargain. Tortoises have been evolving against the bargain's drawbacks for longer than humans have been around, and they still aren't immortal.

rue 11y ago

> Thus evolution tends to weed out immortal or very long-lived organisms. […] Evolution needs death to work. Hence death is built-in. The description of a process in the past that we refer to as evolution could be argued to have benefited from death. Mutation happens anyway. Offspring happens anyway. It does not require death. You could say that death is good because it frees resources for the younger generations—but there is a hidden assumption there: that at some point, there has been some preceding form that did have a vastly longer lifespan and it was less viable because of that. In reality, we have evolved from very, very short-lived organisms, and the trend has been upwards as benefits of those long-surviving members (wisdom, experience, etc. beyond merely bearing offspring) have given an advantage to the survival of species. … However, none of that is actually necessary for the evolution of a species in the sense of a mechanism that reacts or proacts to environmental changes—it can just as well be artificial.

colin_mccabe 11y ago

I think you are misunderstanding how natural selection works. You seem to be implying that there is some guiding hand behind the evolution of each species. In fact, if longer life were an advantage for an individual member of any species, the gene pool would gradually shift towards longer life. Some species do indeed have extremely long lives-- some trees live for thousands of years, and some whales and turtles can live and even reproduce for more than a hundred years. Instead, life length is a tradeoff that is made at the individual level. A longer life means more opportunities to reproduce (or help your offspring), but it also means that you have to set a higher limit for the number of divisions each cell can make, which can decrease cancer resistance. A slower metabolism will produce fewer harmful byproducts, but give you less energy than a fast-burning metabolism. And so on. Longer life makes more sense for more intelligent organisms, since they can be more effective when they're older due to what they have learned. Often, they need teach the young, which can have relatively long gestation times. But an organism's lifespan is always going to be oriented around its reproductive cycle. With all that being said, humans are very clever and I wouldn't be surprised if ways were found around human mortality eventually. I can't help thinking of all the "humans were never meant to fly" arguments that people used to pooh-pooh heavier than air flight in the old days. There's no fundamental reason why life extension couldn't be done except time and effort. But I am not as optimistic as Kurzweil about the timeframe (who is?)