"At best, their biological makers seem to be degraded remnants of genes that cannot be read—broken-down components rather than intact parts of a sequence."
Homology studies. A DNA strand 17 bp long is pretty distinct. If a strand that long or longer was found, we would gain a lot of information about the evolutionary history of dinosaurs that we could never get from fossils.
However, the article isn't clear about what they found. It says DNA, then it says there may not be a recoverable sequence. In that case nucleic acids would be a better term than DNA. Without more info on what stain they used to identify the "DNA", the implications of this research are hard to figure out.
What they found is structures that looked like cells under a microscope: https://academic.oup.com/view-large/figure/200008005/nwz206f... Section C shows cell-like structures and D shows the hypothesised DNA-like structure. They compare with a modern Emu's microstructures in section G.
There was a paper not long ago saying that the DNA half life is about 500k years or so and that most of the DNA would be degraded.
The issue I had with this is why can't we reassemble chunks of DNA like we can with a puzzle.
I'm certain specialized algorithms exist within DNA analysis for this reason. This isn't my field and there are already algorithms that exist on the top of my head that could solve this issue.
The main issue is that you'd have to find a LOT of DNA to build one complete strand and you wouldn't have one strand from one specific animal.
That's the halflife of each bond between nucleotides. After one tenth of a half life you're left with strands of average length ~20 nucleotides. After a full half life they are of length ~2, i.e., mostly just scattered GCs, ATs, etc. After several half-lives, it's almostly completely single nucleotides, and the chance that there are any surviving strands longer than a given length N falls exponentially in time and N.
What does half life of 500,000 years mean? Does that mean any given gene will, on average, split every 500,000 years? Or become unusable in 500,000 years?
65 million years would mean 130 halvings. Basically nothing left, then.
...but this may depend on environmental conditions. this must depend on average environmental temperature, right? Might dinosaur specimens in Antarctic or Arctic regions have experienced significantly lower average environmental temperatures? That could increase the half life significantly.
Maybe we'll find Cryolophosaurus DNA some day...
EDIT: the DNA degradation study specimen was in the south island of New Zealand, which had an average burial temperature of 13C.
Antarctica along the coast has an average annual temperature of about -10C. Further inland and at higher elevation, it's much colder and dryer. Both those increase DNA stability. It's not crazy to me that you might have a factor of 100x greater stability for specimens found where the average temperature over the last 65 million years was 20-40 degrees colder and also dryer.
EDIT AGAIN: Just to support what I said, it seems like a difference of average burial temperature of just 2.5 degrees C doubles the half-life of DNA (and this is multiplicative), so with a 20 degree difference in average burial temperature, that would be 8 doublings of half-life length (factor of 256), so instead of 500,000 years until the DNA was all broken up, you could have 128 million years. https://figshare.com/articles/_Predicted_DNA_half_life_for_v...
so indeed a difference of maybe 40C should lead to a difference in half life of about 20-30%. I think about 30 half lives (~10^-9 degradation factor) should be the limit of recoverability, so perhaps 521x30 = 15k years in normal conditions up to 521x30x1.25 = 20k years in low temperature.
Of course, other factors such as humidity could contribute as well to the half-life, and reactivity is a lot more complicated than the Arrhenius model in reality. But even then I would be surprised such a vast difference in reactivity outside of true cryogenic conditions (maybe even shielding from radiation?).
edit: your second edit is interesting :) is that curve polynomial or exponential?
Oh yes, I definitely messed up my calculations. Half life is (inversely) proportional to the reaction rate itself I guess (I were associating it with the exponent, because half life is usually in the exponent), so the half life itself would be proportional to exponential reciprocal of temperature (e^(a/T)).
This means significant differences in HL for minor temperature variations under e.g. Arrhenius model (consistent with your graph I think). To extrapolate it some parameters need to be estimated though, which sounds interesting, I'll get around to that later...
You raise a very good question. Unlike C14 dating, where the halflife is independent of environmental conditions, DNA is a chemical molecule, whose decomposition is a chemical reaction, dependent on exposure to time, temperature, pressure, light, and chemistry of the environment.
I was hoping the article would explain why the conditions would be so favorable to make it possible.
Right. There must have been trillions of dinosaurs over the eons. Perhaps some individuals were buried in areas with colder conditions and chemical preserving agents. It may take a long time for us to find out.
That's pretty much how modern genome assemblies work. We currently do not have a reliable or accurate way of sequencing DNA longer than ~200 bases. So we fragment the DNA into small pieces, sequence them and then put it all back together.
It's not a completely solved problem as there are features of genomes that can make this process difficult or complicated (repetitive regions, highly heterozygous organisms, etc). Especially with short sequences.
We have technology right now that can allow us to sequence long fragments, but at lower quality and accuracy. There are a lot of tools out there that uses the longer, but lower quality sequences to scaffold the shorter, higher quality sequencing data.
That’s a good enough analogy for modern DNA sequencing.
The code of DNA is an image trapped in an opaque box. Instead of being able to image the complete picture of an organism’s DNA, you take thousands of identical images in opaque boxes, smash the boxes and their contents into tiny pieces to get bits of image out, then line up the now exposed fragments to see the original image.
It is the realignment that is the computationally expensive part of the process.
I mean that a soup of loose nucleic acids can't be sequenced even if we wanted to, we can't learn anything about their genome unless there's actual intact lengths of DNA.
That quote implied the former to me, so- there's not much to be learned from just nucleic acid soup
Even this amount of genetic material is a fantastic find, though. Maybe there's hope of some future technique being able to recover short sequences somehow.
The article is a bit inconsistent on its claims. But in the paper the authors seem to say that intact DNA sequences could exist:
"... to this date, the possible preservation of original proteins and DNA in deep time has not been convincingly eliminated with data."
"Our data support the hypothesis that calcified cartilage is preserved at the molecular level in this Mesozoic material, and suggest that remnants of once-living chondrocytes, including their DNA, may preserve for millions of years."
This is a naive question...but let's just say we do have the DNA, is Jurrasic park possible with today's technology?! I remember reading that someone was trying to inseminate an elephant with mammoth sperm a couple years ago but failed. Not sure if it was because the sample was super old or it just doesn't work.
Whenever this comes up I wonder why no one mentions any associated symbiotic bacteria that might also be necessary for a dinosaur to live. Is it accepted that they could live without any additional microorganisms from the same time period?
It's a completely impossible fantasy. DNA has a half life of ~500 years. Mammoths only died out around 10,000 years ago, which is why it's conceivable that one could be brought back, but all dinosaur DNA has been destroyed for millions of years.
DNA is not a radioactive material. It decays, but there's no absolute law like the radioactive decay, where the half life is the same for every microgram of the same substance everywhere in the world. The average half-life may be 500 years, but there can be situations where the DNA is exceptionally well preserved due to local circumstances. As a simple analogy: the average half life of a human settlement is, let's say 50 years. That means we should see absolutely no traces of human settlements older than 2000 years (40 half-lives). That is far from true.
Researchers in 2016 measured chloroplast DNA in marine sediment cores, and found diatom DNA dating back to 1.4 million years.[62] This DNA had a half-life significantly longer than previous research, of up to 15,000 years. Kirkpatrick's team also found that DNA only decayed along a half-life rate until about 100 thousand years, at which point it followed a slower, power-law decay rate.
Bringing back mammoths based only on DNA seems to me to be akin to bringing back a New Yorker based only on DNA, thousands of years after NYC no longer exists. Even with perfect DNA, I think we underestimate the role that social structure and ecological momentum play in even the simplest of creatures. I think humans are the rule and not the exception when it comes to learning after birth.
And that's not even getting into the complex interaction between a mother and her unborn child, including cytoplasm, mitochondrial RNA, etc. It's not like an organism springs whole cloth from DNA alone.
So the culture issue you raise definitely presents some unrecoverable aspect, but as for the biology, there's certainly a path.
We have animals now that are closely enough related to extinct animals that we could conceivably bring them back through incremental genetic modifications.
For example, if we wanted to bring back Direwolves, we could edit the DNA of a gray wolf maximally such that it can still be fertile and be born by a non-edited gray wolf. This would give you a wolf closer to a Direwolf and then you could repeat this process using each previous generation as the carrying mother for the genetically modified embryo.
What you say might be true, but it might not matter.
If you were to clone a New Yorker thousands of years from now and put them in an exhibit in a Zoo marked "New Yorker", lots of people would be very impressed, even if they didn't start cooking New York-style pizza.
> Even with perfect DNA, I think we underestimate the role that social structure and ecological momentum play in even the simplest of creatures.
I don't think that's true. We raise animals without their parents all the time, both on farms and in zoos. The animals we end up with are still recognizably horses or rats or chimpanzees, with unique behavioural traits that could be studied for years. Even if you lose the social structure of mammoth society, you would still be bringing back something fascinating.
Animals that can be hatched from eggs have even less dependency on their mothers, too.
> It would be a reasonable thing to attempt with today’s technology, but it would be a serious R&D project.
Dinosaurs have enough cultural prestige that it would make total sense to do it as a vanity project if the technology is there.
Similar to turning lead into gold -- there's enough cultural meaning built up around it that someone should do it before it really makes sense in a vacuum.
The key is half-life. A few fragments of dinosaur DNA surely remain, because half-life means there is a certain probability of decay over a particular unit of time. But enough to re-assemble a dinosaur? That's unlikely to the point of near-impossibility.
Even if we got really really lucky and found some that had spent most of its existence frozen deep in Antarctica or something, that would only open the potential of restoring a single dinosaur lineage and not the vast array of species depicted in Jurassic Park. That's total fantasy.
At least on the ancient DNA projects I've worked on, the main obstacles have been a) deamination, b) fragmentation, and c) environmental contamination. Maybe radiation enters the picture at Jurassic timescales, but the DNA would become completely degraded and worthless tens millions of years before that. Unless they somehow managed to find a dinosaur frozen at about 0K, I'm extremely skeptical of these claims.
Right, but even a small amount of water (and presumably, ice) is amazing at absorbing radiation. Wouldn't something buried in a few meters of ice or more be effectively insulated from radiation?
Like hyperbovine mentioned, there are actually other effects that come in to play far sooner, but radiation puts (an additional) hard cap on things, and is easy to napkin-math.
Could you describe half life here? So suppose the strands are now small snippets. If you find enough, couldnt you overlap common parts and eventually re-construct the full length?
It means half of the dna is destroyed every 500 years. After 65,000,000 years, you have 1/(2^130,000)th of the original DNA left, which is to say, none at all.
DNA half-life isn't an immutable property of the material like radioactive half-life is. The environment has an effect. The DNA in cryogenically preserved tissue should have a much longer half life.
It seems to depend mostly on temperature and moisture: dry, cold, and unchanging are best. We have good DNA from Deniovans because it was recovered from bones and teeth that sat buried in a cave in Siberia for 50k years.
Being in amber might protect from moisture, but I think the temperature and temperature swings would still likely destroy it within thousands of years.
Possible? Yes. Practical? Not for 2-3 decades when DNA synthesis capacity gets good enough to synthesize full animal genomes. In terms of raw synthesis power, we do have the ability to synthesize billions of base pairs, but you're going to need other infrastructure around it.
Also, immune problems I don't think would be a huge issue, the adaptive immune system has been around for a while.
" we do have the ability to synthesize billions of base pairs"
This is a valid point. We don't have the technology yet. There was once an SBIR opening for long DNA synthesis but I did not keep track of it. But, given we have the technology it still would not be enough. To slowly make an elephant a mammoth. Yes. Maybe. But making a Tyrannosaurus Rex from scratch is tricky, you also need cells, mitochondria, DNA methylation etc.
The Australian army has had enough difficulty dealing with emus already. Dinosaurs would absolutely wipe them out.
On a more serious note, are egg sizes proportional to the size of the animal, or does the curve flatten after a certain size? I can't imagine an adult T-Rex dropping eggs that are 90cm across, for example, without either breaking them or making the shell impractically thick.
there is a maximum viable egg size, which is about as big as an ostrich egg, due to the square-cube law. Eggs need to be semi-breathable, but as volume increases cubically, surface area increases only quadratically, but surface area is needed for breathability.
So huge dinosaurs had eggs that weren't much bigger than ostrich eggs, containing relatively tiny offspring. Maybe they would have been very cute. Or not, since baby birds often aren't that cute.
Since eggs had to be small, many dinosaurs utilized r-selection, like sea turtles for example, producing large numbers of eggs that only a tiny percent of which would survive to adulthood. This may also be why there were such ferociously efficient superpredator dinosaurs, because there were large numbers of relatively helpless juvenile dinosaurs scampering around to be preyed upon.
The same argument could apply when you take plants or animals from one continent to another when those continents haven't been connected for tens of millions of years.
Yet somehow camels or kangaroos seem to have no trouble living in each others environments.
In fact, you see a bit of the reverse - Banana skin rapidly decomposes in tropical forests where bananas grow, but take one to frigid Norway and drop a banana skin in a forest and you'll still be able to find it in 5 years, while local stuff is decomposing around it.
Assuming we had millions of 3D-scans of different kinds of animals and their full DNA sequence. Wouldn't it be interesting to try to use generative ML methods to generate a dinosaur DNA based on a 3D model?
There’s just no way this would work, the DNA codes organs, proteins and all of the complex molecules and molecular interactions, there’s no way a generative model is going to glean all that from 3D scans.
Could you normally have two viable lineages, each with the same DNA, and each with a different expression of that DNA which is stably conserved over many generations, purely due to womb environment, etc.? In other words, if you cloned a woolly mammoth using an elephant surrogate, might the great great great great grandchildren of this clone still have some characteristics that are due to having an elephant surrogate ancestor?
Or would there be a tendency to converge to a single stable expression due entirely to genetics?
It‘s obvious that in principle the answer could go either way, but I’m not sure whether that’s true in practice, with naturally occurring organisms and naturally occurring DNA sequences. For the sake of this question, one is also tempted to exclude post-natal “cultural” transmission, but it’s not clear that can be easily distinguished.
Whatever happened to the finding 10+ years ago, where scientists found jellified T-Rex bone marrow? It made a huge splash, and they claimed to be able to see structures in the blood, etc, but I haven't heard anything since, and I can't find any follow up research, or I don't know what to google for.
Okay, quick and honest question: How does this support / not support the theory of young earth creationism? For someone who believes that the earth is 6000 or so years old, and that humans and dinosaurs co-existed, and that DNA doesn't last nearly _that long_, this seems like pretty definite proof of that being possible. Counterpoint?
That rests on the premise that dna doesn’t last that long. But maybe it does and that premise is wrong. Alternatively radio carbon dating must be wrong and with it large parts of chemistry. So I would weigh the strengths of both and maybe scrutinize each premise for their respective scientific basis.
Young earth creationism isn't predicated on any kind of consistent or logical position.
Its advocates almost without exception, do not give a shit about the facts, and you aren't going to sway them with another few pebbles added to the absolute mountain of evidence that their position is flawed.
Debating them like their position has merit and is reasonable is a hopeless waste of time, and is in fact exactly what they want because it puts their position on level footing with the scientific consensus.
> I love how not only the time of existence but also its size and appearance are presented as undisputable facts.
All evidence and models across a large variety of disciplines points to the age of the fossils. Geological strata, carbon isotope ratios, phylogenetics, etc.
Feel free to present your evidence so that we can weigh in.
Unfortunately, unlike the author of the first reply implied, I don't have a grand religious take on the issue. I'm simply criticizing what passes for "science" these days. Even if someone grants you all of the evidence you presented, we see regularly that discoveries of this sort are false - be it from contamination in the lab or just an overzealous lab coat.
That said, I can give you a tasty nugget if you want. I reject using uniformitarianism (ad infinitum) as a scientific axiom. And I scoff at the arrogance of my fellow academics, especially for presenting stories such as these as fact.
> I'm simply criticizing what passes for "science" these days.
Using scare quotes like that makes me totally confused what you're trying to say. If it's
I'm simply criticizing what passes for science these days.
then why not say so. The scare quotes give an impression you have a problem with all science, not just bad science, which I don't think you meant.
For a discussion of how poisonous to meaning this practice of using scare quotes can be, see David Stove's chapter Neutralizing Success-Words, an analysis of leading 20th C philosophers of science doing it. http://nekhbet.com/popper/chapter-01.html part 3. It's extremely enlightening and pretty funny, as Stove always is.
So... what good does that do?