Why isn't biological immortality a trait?

[wumpus]

How do genes die?  That is the question.  Death of the individual is irrelevant in the eyes of the gene.  Last I heard, giant sequoia are effectively extinct: even before man's climate change they no longer had the needed ecology/climate to reproduce.  They are pretty much one of the few examples of  (effectively) immortal species out there. 

[GeneralVeers]

10 hours ago, magnemoe said:

This will work just the same if you have a short life and reproduce rapidly, see my example with rabbits. In rapid reproducing animals tend to have pretty frequent booms followed by dieoff.

Yet those species survive the die-offs. Well, most of the time. Minor disadvantage compared to.....well, keep reading.

 

4 hours ago, wumpus said:

How do genes die?  That is the question.  Death of the individual is irrelevant in the eyes of the gene.  Last I heard, giant sequoia are effectively extinct: even before man's climate change they no longer had the needed ecology/climate to reproduce.  They are pretty much one of the few examples of  (effectively) immortal species out there. 

Most of the time, a gene dies out because it fails to adapt to whatever changes occur around it. (don't even get me started about climate change and humans )

Species with short lifespans almost always reproduce more rapidly; that means more opportunities to mix genes, therefore more opportunities for change, therefore faster evolution. That's a big advantage.

No, the species with short lifespans aren't going to evolve into super-advanced creatures with way too many teeth, an appetite for main battle tanks, and a species name with a lot of Z's and Q's in it. The thing about fast evolution is merely that you more quickly reach the optimum balance for whatever environment you're in. Once you reach that optimum and the pressure to survive is relaxed, you tend to stop evolving.

[tsotha]

It's not even clear biological immortality is possible in mammals.  As you age your DNA is degraded in numerous ways (radiation, viruses, chemicals, off the top of my head).  The way your body addresses genetic damage is to kill the damaged cells in order to prevent cancer (not always successfully, sadly).  Over time things start to break down as you begin to have too few of important cell types.  An immortality mutation would have have some way of fixing cells instead of just destroying them.  I can't imagine what the mechanism would be.

Beyond that, as others have noted longevity isn't a particularly desirable trait for a species no matter how desirable it is for individuals.

[WestAir]

2 hours ago, tsotha said:

It's not even clear biological immortality is possible in mammals.  As you age your DNA is degraded in numerous ways (radiation, viruses, chemicals, off the top of my head).  The way your body addresses genetic damage is to kill the damaged cells in order to prevent cancer (not always successfully, sadly).  Over time things start to break down as you begin to have too few of important cell types.  An immortality mutation would have have some way of fixing cells instead of just destroying them.  I can't imagine what the mechanism would be.

Beyond that, as others have noted longevity isn't a particularly desirable trait for a species no matter how desirable it is for individuals.

I imagine it would have something to do with stem cells, or however biologists plan to fix limb loss in humans by growing new limbs for them. I will say that I am not a specialist in biology - in fact - I'd have a hard time out-debating a 1st grader in matters of biology, but from what I've come across on the internet, there are a variety of ways to overcome DNA degradation.

[fredinno]

10 hours ago, GeneralVeers said:

Yet those species survive the die-offs. Well, most of the time. Minor disadvantage compared to.....well, keep reading.

 

Most of the time, a gene dies out because it fails to adapt to whatever changes occur around it. (don't even get me started about climate change and humans )

Species with short lifespans almost always reproduce more rapidly; that means more opportunities to mix genes, therefore more opportunities for change, therefore faster evolution. That's a big advantage.

No, the species with short lifespans aren't going to evolve into super-advanced creatures with way too many teeth, an appetite for main battle tanks, and a species name with a lot of Z's and Q's in it. The thing about fast evolution is merely that you more quickly reach the optimum balance for whatever environment you're in. Once you reach that optimum and the pressure to survive is relaxed, you tend to stop evolving.

Also, animals that reproduce a lot and life short lives often spend a lot more energy reproducing, making it ore difficult to become intelligent. 

[magnemoe]

1 hour ago, fredinno said:

Also, animals that reproduce a lot and life short lives often spend a lot more energy reproducing, making it ore difficult to become intelligent. 

Its two strategies, have few kids and take well care of them or have many as in quantity has an quality of its own. 
And yes smarter animals tend to take more care of kids, they require training and often has long childhoods, humans are the most extreme example. 

[GeneralVeers]

2 hours ago, fredinno said:

Also, animals that reproduce a lot and life short lives often spend a lot more energy reproducing, making it ore difficult to become intelligent. 

Mmmmmm......ehhhhhh......<various other sounds people don't actually make when thinking hard>

I wouldn't say "become intelligent". Short lifespan = less time to learn things, yes. But it's surprising how much a critter can learn in, say, five years. Especially (as is the case with, for example, mice) when every day of your life carries the risk of going hungry or getting eaten by a cougar--risks we humans don't generally face, and which we would consider human rights violations to those humans forced to face those risks......

The capacity for intelligence is mostly genetic, and established before you're even born (larger brain = more storage space for data). After you're born, how much you actually learn and how much you pass on to your progeny is largely up to you and can vary widely. Some people invent nuclear weapons and quantum mechanics formulae; others are dumb as bricks and can't even get your Subway order right.

Gee, ran off on a tangent again. Bottom line: intelligence is certainly a factor, but we humans are unique in the way we applied it to ourselves; elsewhere in nature, evolution pretty strongly favors the critters with shorter lifespans.

[Kertech]

The thing about genetics is that anything that happens to you after the average age of reproduction does not matter from a selection perspective. It's the reason delayed onset of disease is common. Reproduction is quite tricky for us to begin with, and for ancient humans maternal mortality was high enough that menopause (and senescence) were not a problem! Also we do not have an infinite supply of eggs (ovum) and sperm quality decreases over time. 

[mikegarrison]

8 hours ago, Kertech said:

The thing about genetics is that anything that happens to you after the average age of reproduction does not matter from a selection perspective. It's the reason delayed onset of disease is common. Reproduction is quite tricky for us to begin with, and for ancient humans maternal mortality was high enough that menopause (and senescence) were not a problem! Also we do not have an infinite supply of eggs (ovum) and sperm quality decreases over time. 

Not really true in a species like ours. Grandparents can add a lot of survival expectancy to their grandchildren, so evolution isn't quite done with us when we stop having kids. For that matter, childless people can benefit copies of our own genes in other people and their kids (we all share mostly the same genes, of course, being all the same species). From the gene's point of view, altruism and contribution from oldsters is not at all useless.

[KerikBalm]

As to your earlier question, yes, there is a way to extend telomeres. One such gene involved in that is hTERT - human telomerase reverse transcriptase.

It is active to varying degrees in stem cells, germ line cells, and a whole lot of cancer cell lines (there is an hTERT independent way of doing it too). You've evolved to shut it off as a safety mechanism to prevent uncontrolled cell division (cancer)... it doesn't always work.

A body that will eventually become senescent is better than a body that becomes riddled with tumors early on. Just as organisms evolved and the ones that procreate the best become most common, so do cells, your cells in your body are evolving right now, and they are evolving towards an evolutionary dead end - cancer (in most cases its a dead end, there are cases of transmissible cancers in wolves and tasmanian devils - effectively a multicullular organism has evolved into a single cell pathogen).

Reproduction provides the selection needed to keep such mutations in check. A whole lot of germ line cells are not viable or selected against very early on, and then misregulation of cell division can cause developmental problems and a miscarriage.

billions of years ago there was a single cell that divided, it didn't die. It kept on dividing, it has never died. That is now you.

Everyone alive today is composed of cells with an unbroken line of division going back about 4 billion years.

If that's not biological immortality, I don't know what is.

[magnemoe]

13 hours ago, mikegarrison said:

Not really true in a species like ours. Grandparents can add a lot of survival expectancy to their grandchildren, so evolution isn't quite done with us when we stop having kids. For that matter, childless people can benefit copies of our own genes in other people and their kids (we all share mostly the same genes, of course, being all the same species). From the gene's point of view, altruism and contribution from oldsters is not at all useless.

For humans this is true, even if old and too weak to hunt its plenty of task to do back in camp, taking care of and later training kids is the most important. 
This has probably made longer life an benefit on tribe level. 

For animals the gene don't benefit from living after you can not reproduce. Yes you want an safety factor who is most of the reason. 
Animals in captivity has far less stressful life and tend to live far longer. 
 

[radonek]

On 2. února 2016 at 10:52 AM, Kobymaru said:

Early organisms didn't know what death was, but by inventing death we out-evolved those.

out-evolved? Hell, I think I just found me a new favorite word.

On 3. února 2016 at 0:43 PM, GeneralVeers said:

Mmmmmm......ehhhhhh......<various other sounds people don't actually make when thinking hard>

I wouldn't say "become intelligent". Short lifespan = less time to learn things, yes. But it's surprising how much a critter can learn in, say, five years. Especially (as is the case with, for example, mice) when every day of your life carries the risk of going hungry or getting eaten by a cougar--risks we humans don't generally face, and which we would consider human rights violations to those humans forced to face those risks......

The capacity for intelligence is mostly genetic, and established before you're even born (larger brain = more storage space for data). After you're born, how much you actually learn and how much you pass on to your progeny is largely up to you and can vary widely. Some people invent nuclear weapons and quantum mechanics formulae; others are dumb as bricks and can't even get your Subway order right.

Gee, ran off on a tangent again. Bottom line: intelligence is certainly a factor, but we humans are unique in the way we applied it to ourselves; elsewhere in nature, evolution pretty strongly favors the critters with shorter lifespans.

I can see a connection. If you have for example icebergs racing down from poles, a gene for longer,warmer fur is a hot thing, right? And having a shorter life-span is one of things that  make it propagate through genepool faster. Now throw in intelligence: if you can make warm clothes or ignite fire, you can compete with furred ones. But your 'adaptation' can be transfered as meme, freeing you from pressure on  rapid generation exchange.

There are a lot of evolutionary arms races going on most of the time - with viruses, parasites, predators… If you want to outrun a tiger in red queens race, you are gonna need lots and lots of offsprings :-)  But make yourself a spear and race is over. Instead of pressure to spew offsprings and get out of the way, it becomes advantageous to stick around a gather memes. 

[swjr-swis]

I see a lot of assertions of 'laws of nature' that supposedly make immortality an impossible or self-defeating trait. That statistics or evolution do not favour it or make it undesirable. That physics, or DNA, or environmental constraints would never allow it. That unlimited lifespans would effectively turn a species into the equivalent of a pest or a cancer. Etc etc etc. Basically, all the usual responses one could expect from a sentient species who have yet to master living in peace and balance with themselves and their environment long enough to even observe and experience a longer lifespan first hand, let alone learn what actually defines it or how to thrive in that 'condition'.

I think we are afraid to admit that we simply do not know.

We do know there are observable examples in nature of species with (to us) extremely short and extremely long lifespans, and everything in between. For any supposed direct or inverse correlation we think to have found with size or evolutionary 'advancement' or environmental constraints, there are examples of successful species that show the opposite to also be possible.

There are actually examples of species we have never observed dying of old age at all - although that by itself is not considered a proof that it wouldn't happen ever (physics case in point: we still don't fully accept that a proton may be inherently 'immortal', even though we've never observed the natural decay of it).

I submit the following pieces of biological evidence to this exchange:

• Turritopsis dohrnii (the immortal jellyfish) - indication that biological aging can not only be stopped but fully reversed, then back again, at 'will', as far as we know indefinitely.
• Hydra - indication that tiny organisms could be immortal, without overrunning the environment, and that this is not linked to either sexual or asexual reproduction (Hydra can do both).
• Planaria (flatworm) - indication that full regeneration is possible for all organs and body parts, including nervous systems
• Pinus longaeva (bristlecone pine) - indication that immortality does not necessarily require mobility
• Populus Tremuloides (quaking aspen) - indication that huge organisms could be immortal
• Lomatia Tasmanica (king's lomatia) - indication that immortality does not necessarily require genomic diversity
• Tardigrade (water bear) - indication that a single species can survive large variations of environmental extremes and dangers without first having to change, adapt or diversify in evolutionary sense or reach technological 'independence' from the environment. Iow, survival of a biologically immortal species is not inherently made impossible by environmental changes or extremes. And intelligence or technological advancement is not a requirement.

There's also tortoises, lobsters, sturgeons, that for all we have observed may be biologically immortal despite complexity, reptilians that teach us that regeneration is possible for complex organisms, sharks that show that cancer is not an absolute inevitable result of living 'too' long, etc.

All taken together, I think there is quite a bit of evidence that biological immortality is not only very possible, but that a biologically immortal species does not necessarilly end up destroying itself or the environment, and that the trait does not by and of itself inhibit success as a species. So the OP question is very very valid: why indeed isn't it everywhere around us. Why sacrifice the individual for the survival of the species, if it does not seem to be a requirement?

Very interesting discussion so far, but I feel that some of the responses are more indicative of how we try to 'justify' our own lack of longevity, than of how much we truly know about it.

[Kobymaru]

15 minutes ago, radonek said:

There are a lot of evolutionary arms races going on most of the time - with viruses, parasites, predators… If you want to outrun a tiger in red queens race, you are gonna need lots and lots of offsprings :-)  But make yourself a spear and race is over. Instead of pressure to spew offsprings and get out of the way, it becomes advantageous to stick around a gather memes. 

Except even with intelligence and memes going around, simply sticking around the longest is not the most advantagous thing in my opinion. I don't know if you have made the experience, but I find old people to be consistently... stubborn. They have formed opinions in theiry youth, and rarely ever change them.

This extends to ideas or attitudes in societies, that don't actually "change" in the minds of people but simply the people that harbor those ideas die out. Think of racial separation for example: it's not that old people "realized" that they were wrong, they simply got less and less compared to young people who learned that from the beginning.

[KerikBalm]

for many many many creatures, they will die from external causes before their "internal clock" says time is up.

Others die off seasonally because they wouldn't survive (for example) the winter anyway... mate, get those eggs out, and your job is done.

Historically, most humans didn't last past 30. Yet clearly we can live much longer than that. If you die of starvation at 12, or get mauled by a bear at 24, or eaten by a big cat at age 5... there's not much selection for what you'll look like at 60... After a woman reaches menopause... no more eggs, very little selection left to have a benefit for longevity (some studies have suggested that human lifespan is as long as it is not to selection for caring grandmothers who help offspring, but rather to the effect of horny old men who are fertile past their 70s... often wealthy men who well... just imagine a lot of Bill Clinton's in the days before birthcontrol and electronic communication).

It does you no good to have a large population of stem cells ready to divide at 80, if at 20 you start having tumors all over the place.

As you body ages, evolution at the cellular level selects for cells that survive and reproduce in their environment the best ... ie cancerous cells. Ultimately it will doom the organism, the only way to prevent this, is selection at the level of the organism. So organism develop mechanisms to prevent cells from uncontrolled division. Senescence is one defense, and yes it contributes to symptoms of ageing... and you'd be worse off without it.

Its not the perfect solution, but its a solution that evolution has found. Its good enough ofr nature, even if an individual human wishes for a different way.

[radonek]

2 hours ago, Kobymaru said:

Except even with intelligence and memes going around, simply sticking around the longest is not the most advantagous thing in my opinion. I don't know if you have made the experience, but I find old people to be consistently... stubborn. They have formed opinions in theiry youth, and rarely ever change them.

No offense, but your personal opinions of old people are not what directs evolutionary change :-) Look at it this way - during most of its existence Homo Sapiens and its predecesors lived in small clans. Civilization is just small, barely perceptible layer on that, not old enough to actually change us from evolutionary standpoint. And for hunter-gatherer a milion years ago, stubbornes was probably good strategy. Their world did not change nearly as fast, information about landscape and animals can stay valid for generations.

2 hours ago, Kobymaru said:

This extends to ideas or attitudes in societies, that don't actually "change" in the minds of people but simply the people that harbor those ideas die out. Think of racial separation for example: it's not that old people "realized" that they were wrong, they simply got less and less compared to young people who learned that from the beginning.

A year or a generation, does not matter here. Even if it took thousand of years to root out, it would still be blazingly fast compared to evolutionary rate of change. Religions, some of oldest known memes ARE thousands of years old (and mutated all that time). Human race is about two million years old (and still not diverged enough to stop so called races having fun exchanging genes. There is a moral in that.). We are talking completely different scale here. 
 

[GeneralVeers]

5 hours ago, radonek said:

I can see a connection. If you have for example icebergs racing down from poles, a gene for longer,warmer fur is a hot thing, right? And having a shorter life-span is one of things that  make it propagate through genepool faster. Now throw in intelligence: if you can make warm clothes or ignite fire, you can compete with furred ones.

Heheheh. Uhh, no. You don't "compete" with the furred ones. You completely leave them at the starting line. That can't be called a competition.

 

5 hours ago, radonek said:

There are a lot of evolutionary arms races going on most of the time - with viruses, parasites, predators… If you want to outrun a tiger in red queens race, you are gonna need lots and lots of offsprings :-)  But make yourself a spear and race is over. Instead of pressure to spew offsprings and get out of the way, it becomes advantageous to stick around a gather memes. 

Truth be told, this isn't a case of "instead of". Nature tries everything, to see what works. Various species have used both of the above approaches, and clearly they both work.

Humans are actually evolutionarily backwards in a lot of ways. No fur or other protection from cold. No natural armor. No natural camouflage. No claws, poisonous fangs, or other natural weaponry. Slow running speed. Etcetera. Fact is, we're the exception; evolution just doesn't matter to us any more. And it's not really our intelligence, either. It's things such as language, writing, printing presses, and computers--that allow us to store huge amounts of information and then shoehorn lots of knowledge into our kids extremely quickly. Humans have these particular things, possibly flukes (seeing as how no other species on the planet has come up with a real spoken language yet) that allow us to make maximum use of our intelligence, which by itself isn't that much different from the intelligence of whales or elephants.