DNA has a 521-year half-life (2012)(nature.com)
nature.com
DNA has a 521-year half-life (2012)
https://www.nature.com/articles/nature.2012.11555
95 comments
How about frozen embryos and artificial wombs for gestating those embryos X years before arrival?
Then you only need a crew of X people at any given time to keep the ship operational. Some generations would be born and die during the trip (kinda depressing, but I like to think I would be happy in that scenario)
If you don't like the idea of having a machine as your mother, you could also do IVF with the women that are alive and well and constitute ~50% of the crew keeping the ship operational
Then you only need a crew of X people at any given time to keep the ship operational. Some generations would be born and die during the trip (kinda depressing, but I like to think I would be happy in that scenario)
If you don't like the idea of having a machine as your mother, you could also do IVF with the women that are alive and well and constitute ~50% of the crew keeping the ship operational
I'm sure there are ways in which we are still learning and right out of the plot of a film that needs no mention: https://newatlas.com/science/extract-insect-dna-amber/
At the speed of travel you would want to traverse space, wouldn't the time dilation make the half life of passengers less of a problem?
A half-life of 10,000 years means the fraction (0 to 1) of healthy bonds at year t can be modeled by (1/2)^(t/10000). To have 1% bonds broken, it would take an expected 145 years.
EDIT: Fixed the numbers, my bad!
>>> log(0.99, (1/2)**(1/10000))
144.99569695122509I don't understand this. Does half-life even say anything else about the probability distribution?
aren't you assuming specific distribution here?
It's not a terrible assumption to make. We just need to assume[1] that the decay events are independent, that is, every bond flips a coin every 500 years and if it comes up heads, it breaks, independent of what the other bonds do. That is, the process is inherently "local", individual bonds having no way of knowing what the other bonds are doing.
[1] It may be a bit worse in the long run, since if many bonds break, the higher order DNA structure gets damaged and that may change the rate of decay experienced by individual bonds (?).
[1] It may be a bit worse in the long run, since if many bonds break, the higher order DNA structure gets damaged and that may change the rate of decay experienced by individual bonds (?).
half lives (specifically, the "decay" of any individual thing is stochastic but the aggregate of many molecules models exponential decay (in radioactivity. I have no idea what happens in a complex mash of DNA)
This shows the importance of mental gut checks.
If indeed 1% break after 15 years, then 10% (ignoring compounding) break after 150 years, and 50% after 750 years. That doesn’t square with a half life of 10,000.
If indeed 1% break after 15 years, then 10% (ignoring compounding) break after 150 years, and 50% after 750 years. That doesn’t square with a half life of 10,000.
I always forget Bernoulli's inequality. Your gut isn't as clever as mine :)
Your 15 years number is for 0.1%
Even in a -80C freezer with dehydrated and frozen cells they don't recommend over 5 years.
https://www.researchgate.net/post/How-long-can-fresh-frozen-...
https://www.researchgate.net/post/How-long-can-fresh-frozen-...
If you go fast enough, accelerating and decelerating at 1 g, you can travel a million light years in a perceived time of about 27 years.
Yes, but you also need nearly infinite fuel.
An efficient engine could use antimatter as its battery/fuel source and move itself forward by using antimatter to eject propellant close to the speed of light in the opposite direction right? That probably wouldn’t require a large mass of antimatter/propellant. Especially since you can collect propellant from the interstellar medium wherever you’re going
Even antimatter has limits, and those limits deny reaching a relativistic gamma of 1e6/27:
http://www.projectrho.com/public_html/rocket/enginelist3.php
But even if you ignore that limit, at that kind of speed you also need to account for your outer hull undergoing significant damage as each stray intergalactic hydrogen you hit has a kinetic energy of 34.75 TeV in your frame of reference, and while this will create a large supply of antimatter, it will do so in a way significantly less helpful to your goal than the fact we can transmute lead into gold by using the former as a radiation shield in a nuclear reactor is useful to someone who wants to get rich quick.
Bonus fact: this energy level is higher than the LHC, so you may have some extra weird mass-modification effects besides relativity as the front of your spaceship is now a Higgs Boson torch.
http://www.projectrho.com/public_html/rocket/enginelist3.php
But even if you ignore that limit, at that kind of speed you also need to account for your outer hull undergoing significant damage as each stray intergalactic hydrogen you hit has a kinetic energy of 34.75 TeV in your frame of reference, and while this will create a large supply of antimatter, it will do so in a way significantly less helpful to your goal than the fact we can transmute lead into gold by using the former as a radiation shield in a nuclear reactor is useful to someone who wants to get rich quick.
Bonus fact: this energy level is higher than the LHC, so you may have some extra weird mass-modification effects besides relativity as the front of your spaceship is now a Higgs Boson torch.
Nah, just 3e18 kg ;)
That's a more difficult problem compared to DNA repair, crew rotation, or material erosion.
I like your thinking! A couple of points:
(1) we don't really know the threshold yet to be beyond repair I think. It may be 1% but may be 20%.
(2) as others noted, it's 15 years for 0.1% damage using your math.
(3) your timeline directly contradicts the article doesn't it, which suggests keeping people in ideal conditions would have a DNA half life of millions of years.
(4) it's not a given that you need to wake people up to repair DNA. Maybe you just need to bring them to 1 degree Celsius or something. Or maybe nanobots can work on you while completely frozen. I think we are quite far from knowing right now.
So yes, for long term travel DNA repair will be important but how it actually works I think we know little about.
(1) we don't really know the threshold yet to be beyond repair I think. It may be 1% but may be 20%.
(2) as others noted, it's 15 years for 0.1% damage using your math.
(3) your timeline directly contradicts the article doesn't it, which suggests keeping people in ideal conditions would have a DNA half life of millions of years.
(4) it's not a given that you need to wake people up to repair DNA. Maybe you just need to bring them to 1 degree Celsius or something. Or maybe nanobots can work on you while completely frozen. I think we are quite far from knowing right now.
So yes, for long term travel DNA repair will be important but how it actually works I think we know little about.
Good points, but why is it 15 years for 0.1%?
>> crew would probably be awake at all times for repairs etc
If the ship requires human crews to conduct regular repairs, then the ship probably won't last long enough to get where it is going. A ship that is going to last for 10,000 years will need to be built like an Egyptian pyramid, solid enough to last forever and be functional despite millennia of erosion. Putting someone on that pyramid to conduct repairs might sound good, but after 10,000 years those repairs would become just another source of erosion. The activities of that one person would wear down any system with which they interact.
If the ship requires human crews to conduct regular repairs, then the ship probably won't last long enough to get where it is going. A ship that is going to last for 10,000 years will need to be built like an Egyptian pyramid, solid enough to last forever and be functional despite millennia of erosion. Putting someone on that pyramid to conduct repairs might sound good, but after 10,000 years those repairs would become just another source of erosion. The activities of that one person would wear down any system with which they interact.
Erosion in space is much different than on earth. Even the rovers left on the moon 50 years ago should in theory still work.
Except the batteries on that rover are long dead. Many, if not all, of the plastic and paper insulators exposed to vacuum are now brittle and broken. All labels or painted surfaces are likely bleached white. Differential expansion during lunar daylight cycles has likely snapped a few things here and there too. Fifty years of exposure to static electric charges on the moon has put lunar dust in all sorts of places it doesn't belong. Powering up the electrical systems would be interesting/scary. Any metal parts that have been touching each other, again in vacuum, are now contact/cold-welded together. The wheels might still turn, but the bearings are likely shot. And that is all before any talk of micrometeors.
The above poster is talking about physical erosion by human interaction. There are ruts worn into solid rock in many parts of the world with old roads that are only 1000 or 2000 years old. Over 10,000 years anything that is touched by humans will be worn away to no material at all.
Those areas received a lot of traffic, and the rocks in question are not particularly durable as durable rocks such as quartzite are much harder to use in large scale construction projects.
Depending on the speed of an interstellar craft, even trace amounts of dust between stars could be a source of significant erosion over a long enough period of time.
And it’s silly to think about. Who cares. 300 years from now people will be taking trash out in mars and people will be picking it up. We will spread our disease at least within out universe.
There's no biosphere on Mars, nothing alive there, our Terran notion of pollution makes no sense on Mars.
Our Terran notion of pollution makes no sense anywhere without Terran compatible atmospheres.
In a ship with 20 million parts, 19.9 million can probably be automated, but there’s simply 100k parts that can’t always be fixed 100% in advance.
Don’t we have highly durable generational spaceships already? They’re called asteroids. If we find an asteroid that’s large enough to have internal geothermal activity, you could put a bunch of people in an underground system and nudge it into a trajectory towards another star system.
As long as it can support crops, oxygen generation, etc the passengers just proceed to live a “normal” life for the next couple generations until they arrive in orbit around a brand new star.
The hardest part would be maintaining culture to still identify with the purpose of the mission after there’s no one of the original passengers left over
As long as it can support crops, oxygen generation, etc the passengers just proceed to live a “normal” life for the next couple generations until they arrive in orbit around a brand new star.
The hardest part would be maintaining culture to still identify with the purpose of the mission after there’s no one of the original passengers left over
Don’t we have highly durable generational spaceships already? They’re called asteroids.
A planet. You're describing a planet. And we're doing a pretty terrible job keeping this planet we're traveling on sustainable for human habitation.
A planet. You're describing a planet. And we're doing a pretty terrible job keeping this planet we're traveling on sustainable for human habitation.
Well the one we’re on has made it 4 billion years. Getting one to last 10,000 years should be a lot easier
It has only been about 5000 years since humans became sedentary and formed civilisations and we're already seriously disrupting the ecosystem. That's the timeline you'd have to look at.
If we get to a point where we can acquire a planet and hurl it in a specific direction with meaningful speed, then we must’ve developed enough to also keep the planet livable long enough.
Well if you’re gonna do that, you might as well have it accompany a star to give it energy for that journey.
Add a gas giant or two (or 4) to protect it against incoming space debris and help stabilize orbits.
Add some neighboring rocks to also help with that + give them extra material to use once they arrive.
Implant ideas of leaving the rock and coming from a place of great power into the colony’s generational memory.
Include some infrastructure to aid them.
Add a gas giant or two (or 4) to protect it against incoming space debris and help stabilize orbits.
Add some neighboring rocks to also help with that + give them extra material to use once they arrive.
Implant ideas of leaving the rock and coming from a place of great power into the colony’s generational memory.
Include some infrastructure to aid them.
This scenario looks oddly familiar.
Less than a flash in the physical history of this world. Crazy!
> sustainable for human habitation
Even the worst outcomes predicted by climate change models leave some inhabitable regions right? Definitely not sustainable for current population levels though...
Even the worst outcomes predicted by climate change models leave some inhabitable regions right? Definitely not sustainable for current population levels though...
At least on a barren rock, we don't have to worry about disrupting existing natural systems and throwing them into chaos? Starting from scratch as it were, presuming we are responsible enough to maintain it...
How structurally solid are asteroids, comets? I thought they were mostly balls of 'snow'.
I don't think most asteroids are large or dense enough to have adequate geothermal heat to sustain a human population?
Anyone got a back-of-the-envelope calculation for what size asteroid we'd need for this?
Anyone got a back-of-the-envelope calculation for what size asteroid we'd need for this?
For clarification:
Half-life of atoms as in "radioactive decay" (weak, strong and EM force) cannot really be modified by perservations methods. Here [0] a precise answer.
The decay-time of bio-molecular strucutres/bonds (containing information like DNA) can be modified in many ways very easily: low temperatures, exclusion of oxygen (amber) ... I guess "half-life" of DNA is just some fast and crude laboratory proxy for chemical "stability" in a specific setting.
[0] https://www.wtamu.edu/~cbaird/sq/mobile/2015/04/27/can-the-d...
Half-life of atoms as in "radioactive decay" (weak, strong and EM force) cannot really be modified by perservations methods. Here [0] a precise answer.
The decay-time of bio-molecular strucutres/bonds (containing information like DNA) can be modified in many ways very easily: low temperatures, exclusion of oxygen (amber) ... I guess "half-life" of DNA is just some fast and crude laboratory proxy for chemical "stability" in a specific setting.
[0] https://www.wtamu.edu/~cbaird/sq/mobile/2015/04/27/can-the-d...
How does DNA half-life factor into cells and seeds that last thousands of years and are still viable? [1]
I assume seed cells probably aren’t dividing, but I guess maybe they could be using energy and slowly reproducing? And apparently bacterial spores can basically freeze themselves in time for thousands of years and wake themselves up once conditions are favorable.
[1] https://www.newscientist.com/article/dn14125-jesus-era-seed-...
I assume seed cells probably aren’t dividing, but I guess maybe they could be using energy and slowly reproducing? And apparently bacterial spores can basically freeze themselves in time for thousands of years and wake themselves up once conditions are favorable.
[1] https://www.newscientist.com/article/dn14125-jesus-era-seed-...
Bdelloid rotifers over 20K years old have been revived and propagated, and these are actual animals, so we know that in the case of creatures capable of cryptobiosis, there's enough high quality DNA after 20K to sustain life.
To reach cryptobiosis involves packing the interior of cells with materials and reducing metabolism tremendously (I suspect there is still some tiny residual activity, barely measureable), and probably also some repair enzymes for the inevitable strand breaks.
To reach cryptobiosis involves packing the interior of cells with materials and reducing metabolism tremendously (I suspect there is still some tiny residual activity, barely measureable), and probably also some repair enzymes for the inevitable strand breaks.
I believe here they’re referring to the half-life of free DNA. In cells (plant or human) the DNA will be bound by a range of different proteins, wrapped up and packaged (e.g histones, but there are many other types too).
Presumably the half-life of these proteins is shorter than free DNA but their presence will still change the overall half-life.
Environmental conditions are another factor. The inside of a seed could have a more controlled pH, temperature, humidity when compared to the surrounding environment. That would also change the effective half-life.
Presumably the half-life of these proteins is shorter than free DNA but their presence will still change the overall half-life.
Environmental conditions are another factor. The inside of a seed could have a more controlled pH, temperature, humidity when compared to the surrounding environment. That would also change the effective half-life.
I love how the article says that ground water and microbes are responsible for most of the degradation, then blithely quote the computational evolutionary biologist “This confirms the widely held suspicion that claims of DNA from dinosaurs and ancient insects trapped in amber are incorrect" though things trapped in amber are protected from exterior microbes, groundwater, and even oxygen. If they did the study on things trapped in amber they could have come to that conclusion, but they didn’t. Scientists are people and have the same flaws as the rest of us.
There has been some evidence that DNA can be preserved far longer than the half-life would suggest.
https://academic.oup.com/nsr/article/7/4/815/5762999
https://academic.oup.com/nsr/article/7/4/815/5762999
That half-life is obviously applicable only at a given temperature and at a given humidity, because water or similar substances are required to hydrolize, i.e. break, the bonds between nucleotides.
If the DNA molecule is immobilized in a solid, either by freezing or by extreme drying, the half-life will be much longer.
That half-life was for bird bones preserved at 13.1 Celsius degrees.
Even in this paper it was mentioned that at minus 5 Celsius degrees some information from the DNA should remain even after 1 million years.
Unfortunately, there are very few, if any, places on Earth where ancient DNA would have the chance to be preserved for a long time either by freezing or by extreme drying.
If the DNA molecule is immobilized in a solid, either by freezing or by extreme drying, the half-life will be much longer.
That half-life was for bird bones preserved at 13.1 Celsius degrees.
Even in this paper it was mentioned that at minus 5 Celsius degrees some information from the DNA should remain even after 1 million years.
Unfortunately, there are very few, if any, places on Earth where ancient DNA would have the chance to be preserved for a long time either by freezing or by extreme drying.
Look at the link! Claim of possible DNA from a dinosaur. It’s a bold claim (although carefully caveated) but doesn’t seem crackpot to me, especially considering there are other surviving macromolecules like proteins in soft tissue from dinosaurs.
https://academic.oup.com/nsr/article/7/4/815/5762999?login=f...
For now the claim is for possible DNA fragments from the cartilage of a dinosaur, with a length of at least 6 nucleotides, but there is no evidence yet that the fragments are long enough to have preserved any useful information. It is likely that fragments with a length of at least a few hundred nucleotides would be needed.
The paper that started this thread was not about the decomposition of the individual nucleotides, which might be preserved even from dinosaurs, but about the speed of the fragmentation of the DNA molecule, which causes a continuous loss of information until the fragments are so short that no useful information remains.
I certainly hope that we will find cases of extremely lucky preservation of long DNA fragments that are more ancient than what was found until today.
Until now, the oldest DNA that was preserved well enough to allow sequencing of significant parts of it had an age of up to a few tens of thousands of years, e.g. from mammoths, woolly rhinoceroses, cave bears, cave lions, Neanderthal humans etc.
The paper that started this thread was not about the decomposition of the individual nucleotides, which might be preserved even from dinosaurs, but about the speed of the fragmentation of the DNA molecule, which causes a continuous loss of information until the fragments are so short that no useful information remains.
I certainly hope that we will find cases of extremely lucky preservation of long DNA fragments that are more ancient than what was found until today.
Until now, the oldest DNA that was preserved well enough to allow sequencing of significant parts of it had an age of up to a few tens of thousands of years, e.g. from mammoths, woolly rhinoceroses, cave bears, cave lions, Neanderthal humans etc.
The impact that killed the dinosaurs surely ejected some rocks into space. I wonder, what are the odds there's still some space rock floating around the solar system today, holding some ancient DNA, preserved by the cold of space. Perhaps even in nearby Moon or Mars surface?
that would be the worst needle in a haystack problem ever.
.... I don't buy the conclusion.
Science progresses. What's possible in the future can't be predicted today. Let's start with what we can do in 2022 which we couldn't imagine in 1922.
* Of course, we can sequence DNA now (and we know it exists).
* We can also trace back sequences of DNA by when they were created (from splits in evolutionary trees) and extrapolate portions of old DNA of organisms long gone.
* We can probably use machine learning to predict portions of DNA.
Now, let's imagine 2122.
* Will we be able to make inferences from partially-degraded DNA? Perhaps.
* Will we be able to make inferences from the structure about the organism about the corresponding DNA? Perhaps.
* Will our ability to combine inferences grow? Perhaps.
Overall, one thing I've learned is to not predict what's /im/possible. Eventually, engineering finds a way to do some truly counter-intuitive things (and conversely, can't solve problems we'd think would be solved by now; where's my rocket car?)...
Science progresses. What's possible in the future can't be predicted today. Let's start with what we can do in 2022 which we couldn't imagine in 1922.
* Of course, we can sequence DNA now (and we know it exists).
* We can also trace back sequences of DNA by when they were created (from splits in evolutionary trees) and extrapolate portions of old DNA of organisms long gone.
* We can probably use machine learning to predict portions of DNA.
Now, let's imagine 2122.
* Will we be able to make inferences from partially-degraded DNA? Perhaps.
* Will we be able to make inferences from the structure about the organism about the corresponding DNA? Perhaps.
* Will our ability to combine inferences grow? Perhaps.
Overall, one thing I've learned is to not predict what's /im/possible. Eventually, engineering finds a way to do some truly counter-intuitive things (and conversely, can't solve problems we'd think would be solved by now; where's my rocket car?)...
The only way we can travel to the stars is as information. Unfortunately, that requires a receiver at the other end.
If ones goal was to preserve DNA, might it be more feasible to build a digital representation of the DNA and create multiple copies with parity data stored in multiple mediums and distributed to reduce risk of physical damage? Could the DNA be regenerated from the digital data? If not now, in the future perhaps?
you could absolutely make enormous numbers of stone tablets with tiny lithography marks to encode information. Combined with replication and a redundancy code, you could store enormous amounts of information for enormous amounts of time.
But it seems better to just make a dark dry cold repository and store DNA in a matrix that lasts for a long time.
But it seems better to just make a dark dry cold repository and store DNA in a matrix that lasts for a long time.
Do we know the half-life of a digital record?
I suspect that depends on the chosen stored medium. I am assuming perhaps incorrectly that we could find a medium more durable than genetic material with known degeneration rates.
The first thing that comes to mind is the fictional society from the planet Krypton. They stored data in crystals, likely artificially created diamond material. I suspect we could do this today without consideration for cost.
The first thing that comes to mind is the fictional society from the planet Krypton. They stored data in crystals, likely artificially created diamond material. I suspect we could do this today without consideration for cost.
Sorry if my parent comment came of antagonistic.
I was really just asking.
Either way there must be advantages in multiple backups: - DNA - Digital sequence - Crystals - Stone etching
Even with different decay rates they won't all decay in the same way. We can diff multiple records and reproduce a probable original.
(I think - I'm not expert in digital storage or the mechanics of DNA)
I was really just asking.
Either way there must be advantages in multiple backups: - DNA - Digital sequence - Crystals - Stone etching
Even with different decay rates they won't all decay in the same way. We can diff multiple records and reproduce a probable original.
(I think - I'm not expert in digital storage or the mechanics of DNA)
As far as I'm aware stone doesn't erode in space, so we could always just laser in bumps on a stone and read it like a CD. The primary concern then becomes avoiding getting hit by micro debris.
I wonder if you could re-assemble the broken (due to decayed bonds) strands to the most likely sequence, given DNA sequence statistics similar to n-gram language models for human language (= languages with an alphabet of more than 4 letters).
Yes you can, this is how most genomes are sequenced these days. You break the DNA up into a lot of smaller segments that are sequenced in parallel, you then combine them into the larger unified sequence.
https://www.genome.gov/genetics-glossary/Shotgun-Sequencing
You cannot unfortunately do this for dinosaur DNA. The longest human chromosome has 250M basepairs.
With a half life of ~500 years it only takes about 14K years for the chromosome to break down into individual nucleotides. 2^(14000/500) is roughly 170M
https://www.genome.gov/genetics-glossary/Shotgun-Sequencing
You cannot unfortunately do this for dinosaur DNA. The longest human chromosome has 250M basepairs.
With a half life of ~500 years it only takes about 14K years for the chromosome to break down into individual nucleotides. 2^(14000/500) is roughly 170M
Your body does this itself. You have two copies of every chromosome and they’re practical identical. A break in one will be repaired by using the other chromosome. Similarly, even a base change in one strand of one chromosome will be repaired based off the other strand (with a chance that the wrong strand is chosen tho). DNA repair mechanisms like these are exploited by CRISPR and other gene modification strategies: break the part you want to change and then trick the repair mechanism into making the modification you want by providing it with an appropriate template to work off. (Not all CRISPR based techniques use this.)
Is not in contrast with the sequencing of 1.6M old mammoth DNA?
https://www.nature.com/articles/d41586-021-00436-x
Still DNA may be superior to retaining written human records on just about every other media, save stone and metal. Especially longer than recent magnetic media.
Is it reasonable to conclude that no animal that has gone extinct in the last millennium should be unsequencible, given a modest amount of genetic material?
No. Mammoth DNA has been sequenced (15K years old). Perfect conditions for preserving tissue, small fragments can be extracted. Since all cells have the same DNA, fragments that are long enough and have low enough base error rates can be aligned to reconstruct longer fragments (really the same thing as regular shotgun genome assembly).
I would expect if you could find ancient (1Mya) tardigrades preserved as tuns, they could probably be extracted and sequenced.
I would expect if you could find ancient (1Mya) tardigrades preserved as tuns, they could probably be extracted and sequenced.
So the chances that Jurassic Park will be feasible in the future is zero?
The feasibility of Jurassic Park went out the window millions of years ago.
Obligatory "Life finds a way"
https://www.youtube.com/watch?v=oijEsqT2QKQ
https://www.youtube.com/watch?v=oijEsqT2QKQ
I wonder how long any DNA sealed in plant gum/amber would last.
[deleted]
Oh, man, what non-sense.
1. A DNA molecule is billions of pairs long. What does half-life measure? When does a DNA molecule count as destroyed? When one pair breaks, when 10% of the pairs break, when 99.9% of them break?
2. Even if pairs break, so what? When we sequence DNA from various organisms, we start by breaking the strands in small pieces anyway.
3. Even if this half-life had any meaning, it would not be a constant number. Half-life is a constant number for radioactive decay. For other things, it's just a somewhat helpful concept. How long do onions keep until they spoil? Maybe they have a half-life of one week. But, the storage conditions make a huge difference. If you put a lot of onions in a plastic bag, and leave them in a hot, humid and unventilated place, they'll spoil much faster than if you keep them well separated, in a dry and cool place. The same with DNA. In fact DNA's half life is probably days, not hundreds of years. In exceptional conditions, some animal or human remains get exposed to some conditions that make them "fossilize". So, if the 521 year half-life has any meaning, it's a conditional expectation given some exceptional situations. But then some situations are more exceptional than others. The 521 years (ha, just think of it, not 500, but 521! ) is already millions of times longer than the normal decay time of animal tissues. What is to say there are no more exceptional conditions under which the DNA half-life won't be 5 million years?
4. And even if 521 was an exact number, for every type of animal tissue, for all places in the world, that still does not mean we can't reconstitute the DNA's of the dinosaurs. Dinosaurs had both ancestors and successors. The successors are the birds, the ancestors lead to crocodiles, and maybe other animals as well. They have common ancestors with lots of other animals, or more precisely, with all animals. DNA is information. Information propagates. Science comes up all the times with better and better methods to retrieve information. Just look at how your iPhone is able to take a picture at night now, versus 10 years ago. Sure, part of that quality leap is the sensor, but a huge part is the Machine Learning algorithms used for denoising. In other words, for information retrieval.
1. A DNA molecule is billions of pairs long. What does half-life measure? When does a DNA molecule count as destroyed? When one pair breaks, when 10% of the pairs break, when 99.9% of them break?
2. Even if pairs break, so what? When we sequence DNA from various organisms, we start by breaking the strands in small pieces anyway.
3. Even if this half-life had any meaning, it would not be a constant number. Half-life is a constant number for radioactive decay. For other things, it's just a somewhat helpful concept. How long do onions keep until they spoil? Maybe they have a half-life of one week. But, the storage conditions make a huge difference. If you put a lot of onions in a plastic bag, and leave them in a hot, humid and unventilated place, they'll spoil much faster than if you keep them well separated, in a dry and cool place. The same with DNA. In fact DNA's half life is probably days, not hundreds of years. In exceptional conditions, some animal or human remains get exposed to some conditions that make them "fossilize". So, if the 521 year half-life has any meaning, it's a conditional expectation given some exceptional situations. But then some situations are more exceptional than others. The 521 years (ha, just think of it, not 500, but 521! ) is already millions of times longer than the normal decay time of animal tissues. What is to say there are no more exceptional conditions under which the DNA half-life won't be 5 million years?
4. And even if 521 was an exact number, for every type of animal tissue, for all places in the world, that still does not mean we can't reconstitute the DNA's of the dinosaurs. Dinosaurs had both ancestors and successors. The successors are the birds, the ancestors lead to crocodiles, and maybe other animals as well. They have common ancestors with lots of other animals, or more precisely, with all animals. DNA is information. Information propagates. Science comes up all the times with better and better methods to retrieve information. Just look at how your iPhone is able to take a picture at night now, versus 10 years ago. Sure, part of that quality leap is the sensor, but a huge part is the Machine Learning algorithms used for denoising. In other words, for information retrieval.
1. From the article:
> By comparing the specimens' ages and degrees of DNA degradation, the researchers calculated that DNA has a half-life of 521 years. That means that after 521 years, half of the bonds between nucleotides in the backbone of a sample would have broken; after another 521 years half of the remaining bonds would have gone; and so on.
> By comparing the specimens' ages and degrees of DNA degradation, the researchers calculated that DNA has a half-life of 521 years. That means that after 521 years, half of the bonds between nucleotides in the backbone of a sample would have broken; after another 521 years half of the remaining bonds would have gone; and so on.
Oh, man, what negativity.
Even if the term “half life” isn’t really appropriate here, it’s clear enough (and explained well enough) in the article. This isn’t a published scientific paper, this is an article likely meant for a more general audience, so, jeez, cut it some slack.
Even if the term “half life” isn’t really appropriate here, it’s clear enough (and explained well enough) in the article. This isn’t a published scientific paper, this is an article likely meant for a more general audience, so, jeez, cut it some slack.
Fair enough, I was too negative. I'll leave my comment unedited, so people won't get confused about the exchange.
The article itself is ok, and the researchers had good intentions. The problem is the idea took a life of its own. It almost became a meme. I heard this article many times quoted on HN. And the idea itself is definitely wrong, and needs to be debunked.
If the 521-year half-life were remotely true, we couldn't hope to ever sequence something older than 100 or 1000 half lives (i.e. half a million years). Well, we did that just the year after (this article was published in 2012, we sequenced a 500k year old fossil in 2013) We also sequenced a one million year fossil in 2021 [1])
[1] https://www.nature.com/articles/d41586-021-00436-x
The article itself is ok, and the researchers had good intentions. The problem is the idea took a life of its own. It almost became a meme. I heard this article many times quoted on HN. And the idea itself is definitely wrong, and needs to be debunked.
If the 521-year half-life were remotely true, we couldn't hope to ever sequence something older than 100 or 1000 half lives (i.e. half a million years). Well, we did that just the year after (this article was published in 2012, we sequenced a 500k year old fossil in 2013) We also sequenced a one million year fossil in 2021 [1])
[1] https://www.nature.com/articles/d41586-021-00436-x
You should read the article and not comment based on the title and your preconceptions. All of your questions are addressed in the text of the article.
Agree. It's unclear from the article that information cannot still be reliably obtained from the sample. Sure the bonds break, but since the construction of nucleotide bases are well understood, does that mean these cannot be distinguished in the sample?
Read the page. Half life is precisely defined.
Your claim half-life doesn't apply is incorrect. All atoms undergo radioactive decay, so half life applies as precisely to all matter as is does to uranium.
Your claim half-life doesn't apply is incorrect. All atoms undergo radioactive decay, so half life applies as precisely to all matter as is does to uranium.
> All atoms undergo radioactive decay
Are you sure about that?
Are you sure about that?
So far the isotopes called "stable isotopes" are ones with unobserved decay, and slowly over time ones that used to be called stable are being found to decay (e.g., Bismuth 209). Quantum uncertainty (and still theoretical proton decay, expected to happen, just not measured well yet) are expected to get the rest.
Ultimately quantum tunneling will get them all. There is no known mechanism to prevent it.
Ultimately quantum tunneling will get them all. There is no known mechanism to prevent it.
I think the term "effectively stable" is what is meant in this context.
i guess he has never heard of a stable isotope.
Even if it were true that all atoms had a half-life, "DNA" is not an atom.
Doesn't matter. Half life is used for anything that is modeled with exponential decay: energy systems, medicine effectiveness, caffeine in a body, oscillations.
So if the essence of a thing breaks down, and the model for it is exponential decay, then it has a half life.
Thus DNA has a half life, just as the paper in Nature, one of the premier scientific publications in the world, demonstrates.
So if the essence of a thing breaks down, and the model for it is exponential decay, then it has a half life.
Thus DNA has a half life, just as the paper in Nature, one of the premier scientific publications in the world, demonstrates.
Nonetheless, "atomic radioactive decay exists and DNA is made of atoms" is not the reason DNA has its half-life, as your post claimed.
No where did I claim the decay is the one used in the article, in fact, my first sentence is "Read the page. Half life is precisely defined." I was well aware of their definition.
My explanation was to point out that even if you don't like the definition in the article, that there are other valid ways to define half-life for atoms and complex molecules.
My explanation was to point out that even if you don't like the definition in the article, that there are other valid ways to define half-life for atoms and complex molecules.
However, in temperature below zero at -5 degrees Celsius for example, half life of DNA is actually 10,000 years or more. https://en.m.wikipedia.org/wiki/Ancient_DNA
Still, this would also only allow 200 years of freezing before more than 1% of bonds would have been broken.
The third and probably most viable option is to wake up the crew every 200 years to repair accumulated DNA damage.
Also, a small percentage of the crew would probably be awake at all times for repairs etc., so the crew could rotate every 200 years.