Natural environment to force evolution to Immortality

Question

Which natural conditions are needed to force the evolution to immortality? I've read on a page (I don't remember the page) that if the environment is safe, the animal would evolve to have a shorter lifespan and large amounts of offspring and if the environment is dangerous the animal would evolve to have longer lifespan and small amounts of offspring, because it's too complicated to take care of a baby animal in a dangerous environment. But I've read on other site that the more dangerous an environment is, the more offspring would be produced to increase the chances of survival of the race.

So my question is: which natural conditions are needed to force the evolution to longer lifespan and even immortality?

Bonus: Which natural conditions are needed to force humans (humanoids) to evolve to immortality?

Answer 1

tj1000 mentioned the idea of optimizing accumulated knowledge. I will explore and develop that idea.

What we need is a situation where knowledge continues to be accumulated over time, and cannot be passed on during a normal growing-up period. One reason might be because the elders remember places or situations that don’t occur every season, or even every generation if using the traditional span of growing up, reproducing, and passing on skills to children as they grow up. The Grandmother Effect (mentioned by Palarran) might be a primitive form of that.

Consider that animals learning only by doing and being shown by adults have no other way of recording history and passing it on as abstract knowledge. A troupe following the food sources may range over a large area, and not return to the same area for a time greater than a generation. Furthermore, you have a cross product of location and climate. So, to plug in some numbers, if a childhood is 15 years, the parents will be 30 when they are done teaching their own kids and the cycle repeats. But knowledge about where to find a fresh-water spring during a dry year in this specific region is not something the parents ever experienced themselves. In fact, the last few times the troupe passed this way, it was wet weather. So, where’s that spring? Maybe an elder does remember.

Having memory-keeper elders live longer and longer will allow them to recall more situations, which is only collected from their own direct experience. The younger elders-to-be are shown the spring. They might need to remember that 5 or 6 generation-cycles later, only then passing it on in turn.

The water example is inspired by the case of Elephants. It was long rumored that they have “generational memory” but actually they simply live 60–70 years: compare with females being sexually mature at 9 and adults at 18. So an old elephant may be a grandmother at 40 and a great-grandmother at 60 and remember things that she wasn’t able to pass on to her children earlier.

To recap, favor extended lifespan in a social animal by having a large variety of changing conditions that are not repeated frequently.

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Meanwhile, we have the issue of actually living that long. Cells have a pre-programmed number of copies they will make because they do degrade. It’s interesting that the rate of cancer in animals doesn’t scale with the lifespan and overall size — the amount of compensating traits will improve to match the need. But that can’t scale up indefinitely.

Macroscopic living things with specialized tissues that do seem to be immortal will actually go through rebirth, not actually lasting without tissues wearing out. Plants, you understand, spread vegetativly, growing all new parts from a shoot. A certain jellyfish reverts to an earlier stage in its lifecycle and metamorphosises again.

So, how about starting with species that do undergo metamorphosis? Consider butterflies: they don’t gradually turn into adults; rather, they undergo a full development process in the same way as a fetus in an egg does.

So imagine a phylum descended from ancestors that had a complex lifecycle with different instars and underwent metamorphosis. As evolution took it towards more advanced life, it kept the ability and undergoes partial metamorphosis so that it can keep the brain with its learned experiences. They might have different forms at different ages or have different casts with different bodies, all based around this inherited original lifecycle. Now, an adult might morph again to become an “elder”, and continue renewing its form every generation by repeating the metamorphosis but targeting the same form again.

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Why can't body parts be regrown? If an animal can have offspring, then clearly it’s possible to fire up the development process from a single “good” cell. I think that’s getting off topic and is worth its own question. I’ll just leave you with the idea that targeted, partial metamorphosis could evolve into such an ability. Essentially, your offspring keeps your old brain with everything you learned, but can evolve physically otherwise!

Answer 2

There is a (fictional) talk about this by the protagonist in Fragment. He makes an argument that lifespan is evolved to prevent inter-generational reproduction, and different lifecycles and lifestyles give rise to different spans. In a situation where an animal is unlikely to meet its own direct offspring (e.g. mating is done in an annual mass congregation as opposed to a small local community) that pressure does not exist.

Eventually, they explore an ecosystem where predation is so severe that there was no need to evolve an obsolescence mechanism; meanwhile they also have a system like with bees where an animal only mates once and stores the material for life, thus no inter-generational mating was possible and that pressure was not needed. The intelligent life they discovered has individuals that live for tens of thousands of years and never grow old.

Answer 3

Try looking at this List of longest-living organisms, and you'll get a clue of what animals potentially live longest.

The closest you can have is prolonging the lifespan, maybe into hundreds, or even thousands. But no immortality. Nature has dropped a "wear and tear" rate on each and every single organism, which is designed to allow natural selection pressure evolution.

I became interested in this topic back when I read a book about genetic (I forgot the name or the author, but he was a journalist).

What is aging? Google it, you won't be disappointed.

Everytime your cells multiply, your DNA strand is cut shorter than its original length. That's why the longer we live, the more we accumulate malformed cells, manifested as wrinkled skin, blurry eyes, forgetful memory, and such. It's because the newer cells have their DNA strand cut short on their endpoints - might be a very important information about a certain enzyme.

ABCDEFGHIJ -> ABCDEFGHI -> ABCDEFG -> ABCDEF

However, nature has developed an interesting protection against this: telomere, a "useless" repetition of a meaningless section, placed on the ends of a DNA strand, giving a margin to protect important information. It delays the "aging" of the DNA.

ABCDEFGHIJtttt -> ABCDEFGHIJttt -> ABCDEFGHIJt

An organism with a longer lifespan has longer telomere. A short lived one has shorter.

However, dangerous environments (predators, or such) remove the advantage an organism with longer telomere has (they die before using up their telomere), causing them to evolve with shorter telomere. Therefore, "endangered" animals - usually small animals, which are prey to many predators - usually have a short lifespan with a lot of offspring.

Longer lifespan vs reproduction

In nature's view, after the reproduction age, you are basically useless. It's better for you to die quickly and efficiently, allowing the food and effort to maintain the survivability of your offspring.

An aged body means that you have accumulated many failures in your body: heart, liver, kidney, reproductive system - that's why it's even better for you to die quickly, to prevent you from passing down cut genes to your offspring. To maintain this body you spend energy to repair the damage internally and externally. If you are not about to give birth to more healthy offspring, then nature deems it's better to reallocate the energy to other things.

Thus, it's far more efficient to have babies rather than maintaining an aged body - which consumes energy that can be reallocated to having more babies.

If they have no or few endangering factors, the pressure of natural selection will encourage individuals with longer telomere to survive better.

Bonus: There is an enzyme called telomerase that is able to "repair" cut telomere, but it is not active continuously. However, in some organisms this telomerase is active more often.

For human/humanoid, the key factor is stress. Removing stress will greatly increase individual human to live (because stress suppresses the defense system), allowing individuals with longer telomere to have advantage, thus evolving humanity to have longer and longer telomeres.

Answer 4

This is dependent on the species as much as the environment. I would recommend a creature with slow reproduction and few offspring that is slow to reach maturity, set in an environment with very high infant mortality. If a species has to have a long life simply to breed enough to carry on the species, either that species will go extinct or evolution will find a way.

For an example, let's imagine some species of mammal that is pregnant for a year or more to give birth to a single child. For the purpose of this example, say it takes twenty years between a child being born and it becoming sexually mature (and thus able to reproduce). Let's also stipulate that the environment is dangerous enough that most children die before they reach that age. In principle, this doesn't even require any special environment; prior to the Industrial Revolution, fewer than half of all humans lived to adulthood (with the result that lifespan figures tend to give a misleading picture of how long people could live back then), and humans are (supposedly) intelligent. It doesn't take much exaggeration from there to envision an environment where four-fifths or more of a large mammal's offspring die before reaching sexual maturity.

If it takes this species, say, eighteen months at minimum between births, and four-fifths of those children die before they become mature enough to themselves reproduce, that species will require a high maximum life span simply to perpetuate itself. Under that scenario, you would get roughly one adult every eight years under ideal circumstances. This mandates that adults live thirty-five years at the barest minimum, and there will need to be a considerable margin for safety (ideal circumstances being practically non-existent in reality). A species like that would have to live fifty years or more in practice (barring accident, predation, illness, etc.) just to produce enough offspring; assuming this species also raises its young, cares for them, etc., that adds another fifteen or twenty years before members of the species can afford to enter into old age.

Under this example, you'd end up with an average life expectancy for adults (excluding the many, many casualties who die before adulthood) of at least seventy years, and this isn't even an example that stretches very far beyond humanity; exaggerate the figures for pregnancy/time to maturity/infant mortality/all of the above, and you can get an even larger figure simply as an evolutionary requirement. Raise the duration of pregnancy to thirty months, for instance, and you end up with an average of one living adult every twelve or thirteen years (again, under ideal circumstances) instead of every eight; your average lifespan for adults would then become something closer to a hundred years. If you want more focus on the environment, exaggerate its dangers (high number of predators, high disease rates, whatever works) and spike infant mortality, with a similar result.

None of this will select for outright immortality, however. If you want that, you're going to need a way to avoid overpopulation. There's also a problem of genetic dominance; a handful of immortal individuals could go on having children forever, making their genes too widespread, which would effectively create inbreeding within a few generations due to nearly everybody being descended from the same great-grandparent or some such scenario. If they have some equivalent of menopause, you instead run into the problem of justifying why they live forever, consuming resources that could be going to their offspring, when they can no longer reproduce; the Grandmother Hypothesis might give you some pointers for that, but on its own I don't think that would ensure immortality.

Answer 5

The Telomeres and Telomerase have already been mentioned in an answer. But in my opinion not sufficiently explained.

First of, a Telomere is the repeating sequence that prevents aging by absorbing your DNA shortening; telomerase is the enzyme and adds more repeats to your telomeres after you loose a bit.

"But wait!" You probably think "If we already have an enzyme that repairs this damage why do we even age?" Only two cell types express Telomerase:

1. Stem cells. Your stem cells have more preserved DNA than your normal cells, from a stem cell replication one cell stays a stem cell, the other becomes a 'normal' cell. Normal cells also replicate and their DNA damage accumulates, but a certain percentage of them each 'generation' of cells originate from stem cells and will have long telomeres.

"This enzyme sounds incredibly useful! Why doesn't every cell simply express Telomerase?" That's where we come into contact with the second cell type that has to express telomerase.

2. Cancer. An incredibly amount of cancer cells will die before they replicate. Your immune system attacks cancer, cancers are under constant food and oxygen shortages, cellulair defense mechanismes will self-destruct the cell as soon as they notice they are a cancer cell. Not to mention all the mutations might leave a cancer cell simply unable to function. One of those cellulair defense mechanismes I mentioned is the telomeres. Due too their incredibly high attrition rate and accompanying high reproduction rate cancers will go through their telomeres fast, and if they don't make specific mutations to express telomerase they will die. It is safe to say that every single person reading this has had a mutation and a cancer in their life, but this cancer would have died off before it became noticeable because it ran out of its telomeres; didn't make a "lucky" mutation to express telomerase and died. I will repeat this: Every one of you has been saved from having a tumor because your normal cells do not express telomerase.

Cell immortalization is a giant hurdle; the fact that your cells have a build in self-destruct timer that will go off after a set number of generations is what enables complex life to exist.

If you want immortal life you again have two options:

1. Your beings produce telomerase in every cell and your cells have no other major differences from Human cells. Your beings are immortal but plagued by cancer and tumors.

2. Your beings produce telomerase in every cell but they have additional cellulair defence mechanisms. I'm not going to give an entire lecture on Oncology so let's just say that your Telomeres are not your only way your cells 'realize' they are a cancerous growth and self-destruct. If you say those other mechanismes are sufficiently advanced and numerous they might very well offset the massively increased cancer risk that telomerase expression gives.

Answer 6

Really sorry for the long answer. It's the product of too much coffee.

tldr;

Kill off the people that weren't going to live long with, for example, a virus that shortens your telomeres.

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When you think about evolution you have to think about one thing above all the others. Reproduction. Evolution is driven entirely by and for reproduction. If we're smarter than homo heildelbergensis then it's because being smart helped us reproduce. It either helped us find resources or stay away from danger, but the reason for being smart is so that you can indirectly, reproduce better. To turn it on its head, if being smarter only meant that we all became basement dwellers and never saw the light of day, we wouldn't be very sexy, and probably wouldn't reproduce. If that were the case the species would not become smarter.

Fitness is a term that in this context means reproductively fit. Your fitness is basically how well you reproduce. So if it's a thousand of years ago and you're big and strong and you're able to hunt and protect your family, then you reproduce. Your genes get passed on. Your offspring survive to become big strong people and so on. There are counter examples where being bigger might be a disadvantage but let's leave those for another discussion. This is just a simple example.

Another important thing to remember is that evolution does not go towards anything. There is no end goal in mind. A bear has a white coat when its brothers and sisters all have brown coats. The white coat helps him hide in the snow. There was no force that was driving him towards whiteness, it just happened randomly and it turned out to be a little better than brown. He hunted better, got fed and that let him reproduce more than everyone else.

Now let's start the experiment. We want immortal human beings. How do we get there? Currently, "all things being equal" (they're not, I know), everyone of breeding age is reproducing. That means that people who will live to be older than 100 and people who will kick it in their mid 60s are all reproducing. Right now there's no fitness related to longevity. Everyone can start breeding when they're done puberty regardless of how long they're going to live. So that would need to change.

Let's just say that since we do have a goal in mind (immortality), we can build to that goal gradually and have intermediate goals (longevity). So we allow for some circumstance that takes people who weren't going to live that long out of the gene pool. They are no longer reproducing. Not with our octogenarians, not with each other, nobody. Their short lived genes will die with them. Now we have a breeding population of very old people.

As other posters have mentioned, it really is about that reproductive age. Once you hit menopause you are no longer passing along your genes. Whatever you already passed along is what you passed along. If you live to be 300 after you hit menopause it won't matter because no one knew you were that sexy and you never reproduced more than the average person, let's say. So it's not enough to just live longer in and of itself, you must retain your ability to reproduce in order for that to be a fitness factor.

So that's it really. Those that won't live long must not reproduce (or reproduce as much, depending on how long you want the immortality process to take), and those that live longer must reproduce more. The question is how do you know? And that's what your original question is all about. What natural conditions will lead to this outcome?

Without knowing ahead of time who is going to die of natural causes early and who is going to age like wine, natural conditions can't really select those people. So you're going to need to invent a mechanism that can tell who is going to die early, either directly or indirectly. Here's where it gets interesting.

Imagine a virus like any other virus, except that it doesn't kill the host. It makes a copy, leaves a gene in your cell that says "do not infect me" and then leaves you alone. It's a whole other class of virus, real smart and sustainable virus. Let's add one curious effect of this virus: it decreases your telomere length (if you believe this is the basis of all aging and not a cumulative set of deteriorating genes or other mechanisms). So it makes everyone age. Everyone gets the disease, everyone is infected. Everyone is aging way faster than they should be. See where I'm going with this? :) So who lives? The people whose cells just happen to be slightly better at repairing telomeres. So they reproduce and only they reproduce, which leads to the start of generations of ubertelomeremensch.

This is one way but you could do it other ways. Maybe radiation from a star makes everyone age and mutate and only organisms with strong DNA repair (not just shielding) can survive. Basically, you want the people to die off who aren't going to live long anyway. That'll do it. You make the people who will live long more reproductively fit and they'll evolve to at least very long lives.

And we are talking about the species as a whole. If you wanted to do an offshoot and say "these jungle people over here bred mortality right out of their stock", you could do that too.

To be ever weary of the randomness of the process however, and as a counter example, evolution might prefer people with a certain protein or a certain overactive organelle. And, at first, it may have nothing to do with longevity, but through the course of random evolution it will provide the key function to repairing cells and DNA indefinitely.

Other interesting things to consider: the cells in your body come from your parents, those cells came from their parents, those cells came from their parents. If you follow the line all the way back you end up with some thing in our sweet mother Earth's history that found a way to reproduce itself over and over until we ended up with you. It might not be the same person, but it's life. That's called germ line immortality, and it's pretty dog gone amazing.

I had another point to make but I forgot it. Must be getting old.

Answer 7

I will sort of answer this by pointing out that immortality is contrary to evolution, because it stops the improvement process.

Evolution, which we can observe, occurs during reproduction. If we assume that the evolved version may contain improvements over the original, then the original is now just wasting resources by continuing to live. The individual creature may be at odds with that goal, but that's how living creatures as a whole operate - they reproduce to spread the species, and to improve the species.

Human intelligence may lead to some form of intervention to either stretch life further or make it immortal, possibly by engineering DNA strands with super long telometers, or mods to the replication process to stop the loss. But, if one follows how life has evolved naturally, immortality is just not one of the goals the evolution process seeks to achieve.

Perhaps the next stage of evolution is intellectual evolution, where the individuals are preserved so they can continue to contribute based on their accumulated knowledge. But, it will be up to humans to intercede in the evolutionary process, to achieve that goal. The natural mechanism itself is not set up to achieve immortality.

Answer 8

The humanoid species would have to develop and evolve in an environment that maximized intelligence and skills and abilities necessary for technical work. Also, they would need to develop the psychosocial factors towards self-centredness.

Once the humanoids created science and technology eventually as their technical culture increased they will develop advanced biomedical technology capable of enhancing and extending longevity. Given sufficient time the humanoids might find a way of developing technologically mediated immortality.

In summary, the humanoids need to evolve to be capable of producing high level advanced technology. This will lead to increasing levels of life extension and longevity which eventually could turn into immortality.

Answer 9

There may be a natural way to immortality.

Evolution, like others already mentioned, is tightly coupled with mortality. So, let's imagine an environment that has no need for evolution. A environment with very, very constant conditions. In that environment, an organism can reach its "optimal form". Once optimal form is reached, any modifications to that form would be detrimental. So, if everything going according to plan, that environment eventually will get populated by that only form of the organism. Next thing, it would be very beneficial for such organism to be long-living, and replicating all the time. Sure, it may lead to overpopulation, but all forms would suffering from it. Longevity ensures proliferation of the optimal form. A form with shorter lifespan would, over the course of its life, produce less offspring and therefore is not optimal. At the end, we would end up with the environment populated by of potentially immortal organisms competing with each other for limited resources.

Answer 10

fet's answer is really good, and I will use that mechanism to try to give the OP a method to achieve the desired outcome.

Indirect natural selection means that some individuals reproductive fitness might be influenced by others. This is a form of social natural selection.

If you accept that the way to immortality starts trough longevity you want a selective pressure that allows the elderly to keep being productive and helpful to they families after they cant reproduce anymore.

For cavemen that could be two natural challenges, one that cannot be overcame by elders and one that can. Lets imagine a village of hunters. This hunters need to walk a long journey everyday to catch their prey, and at night there are predators outside. Elders have a hard time hunting for lack of agility and stamina.

Now lets add trouble at home... say, deadly ants. Our village has plenty of anthills and no way to kill them. Also the ants can get aggressive if disturbed, which children often end up doing.

So a small family of 3: father, mother and one child needs food and protection for the child. If the mother can help with the hunting/gathering of food she will not be able to without leaving the child unattended.

If this family included a grandmother the mother would be able to go and help hunt without endangering the child. In this way the father/mother chances of raising a child would be increased by the longevity genes os his/her mother.

Answer 11

In no natural environments, immortality will arise in complex life forms. For complex life forms to arise, many mutations must take place. If mortality were to take place, it would reduce the rate of these mutations since life forms have to reach equilibrium with their resources. This means exhaustion of those resources and it is not beneficiary to feed an older generation when you can feed the new ones.

Many are often confused that evolution is an extremely random process. It is not! The whole point of sexual reproduction and desires is to make it semi-supervised. Similarly, aging is another tool to make life more diverse.

So, to answer your question, once the perfect life form for a particular environment has been reached, deviations from it are undesirable. Hence, in such a case, immortality can be a solution to preserve the perfect living code. I doubt that such a solution exists for a dynamic and a self-interacting systems/environment in which life will arise and in which life will reshape it.