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.
