Why can't you clone a dinosaur?
Editor's responseThe idea of cloning dinosaurs from fossil remains was especially relevant after the release of the film “Jurassic Park,” which tells how a scientist learned to clone dinosaurs and created an entire amusement park on a desert island, where you could see a living ancient animal with your own eyes.
But a few years ago, Australian scientists under the leadership Morten Allentoft And Michael Bunce from Murdoch University (Western Australia) proved that it is impossible to “recreate” a living dinosaur.
Researchers radiocarbon dated bone tissue taken from the fossilized bones of 158 extinct moa birds. These unique and huge birds lived in New Zealand, but 600 years ago they were completely destroyed by the Maori aborigines. As a result, scientists found that the amount of DNA in bone tissue decreases over time—every 521 years, the number of molecules is reduced by half.
The last DNA molecules disappear from bone tissue after about 6.8 million years. At the same time, the last dinosaurs disappeared from the face of the earth at the end of the Cretaceous period, that is, about 65 million years ago - long before the critical threshold for DNA of 6.8 million years, and there were no DNA molecules left in the bone tissue of the remains that archaeologists were able to find.
“As a result, we found that the amount of DNA in bone tissue, if kept at a temperature of 13.1 degrees Celsius, decreases by half every 521 years,” said research team leader Mike Bunce.
“We extrapolated this data to other, higher and lower temperatures and found that if you keep bone tissue at a temperature of minus 5 degrees, the last DNA molecules will disappear in about 6.8 million years,” he added.
Sufficiently long fragments of the genome can only be found in frozen bones no more than a million years old.
By the way, to date, the most ancient DNA samples have been isolated from the remains of animals and plants found in permafrost. The age of the found remains is about 500 thousand years.
It is worth noting that scientists will conduct further research in this area, since differences in the age of the remains are responsible for only 38.6% of the discrepancies in the degree of DNA destruction. The rate of DNA decay is influenced by many factors, including the storage conditions of the remains after excavations, the chemical composition of the soil, and even the time of year in which the animal died.
That is, there is a chance that in conditions of eternal ice or underground caves, the half-life of genetic material will be longer than geneticists assume.
Erenhot, city of dinosaurs. Photo: AiF / Grigory Kubatyan
How about a mammoth?
Reports that scientists have found remains suitable for cloning appear regularly. Several years ago, scientists from the Yakut North-Eastern Federal University and the Seoul Center for Stem Cell Research signed an agreement to work together on cloning a mammoth. Scientists planned to revive the ancient animal using biological material found in permafrost.A modern Indian elephant was chosen for the experiment, since its genetic code is as similar as possible to the DNA of mammoths. Scientists predicted that the results of the experiment would be known no earlier than in 10-20 years.
This year, messages from scientists from the North-Eastern Federal University appeared again; they reported the discovery of a mammoth that lived in Yakutia 43 thousand years ago. The collected genetic material suggests that intact DNA has been preserved, but experts are skeptical because cloning requires very long DNA strands.
Living clones
The topic of human cloning is developing not so much in a scientific way, but in a social and ethical one, causing controversy on the topic of biological safety, self-identification of a “new person”, the possibility of the emergence of defective people, also giving rise to religious controversy. At the same time, animal cloning experiments are being carried out and have examples of successful completion.
The world's first clone, the tadpole, was created back in 1952. Soviet researchers were among the first to successfully clone a mammal (house mouse) back in 1987.The most striking milestone in the history of cloning living beings was the birth of Dolly the sheep - this is the first cloned mammal obtained by transplanting the nucleus of a somatic cell into the cytoplasm of an egg lacking its own nucleus. Dolly the sheep was a genetic copy of the cell donor sheep (that is, a genetic clone).
If under natural conditions each organism combines the genetic characteristics of its father and mother, then Dolly had only one genetic “parent” - the prototype sheep. The experiment was carried out by Ian Wilmut and Keith Campbell at the Roslyn Institute in Scotland in 1996 and was a breakthrough in technology.
Later, British and other scientists conducted experiments on cloning various mammals, including horses, bulls, cats and dogs.
Regarding organic material, can dinosaur DNA be extracted from it? Not really. Paleontologists constantly argue about the suitability of organic matter, but DNA has never been extracted (and, apparently, never will be able to).
Take, for example, the Tyrannosaurus rex (which is a rex). In 2005, scientists used weak acid to extract weak and pliable tissue from the remains, including bone cells, red blood cells and blood vessels. However, subsequent studies showed that the find was just an accident. got seriously excited. Additional analysis using radiocarbon dating and scanning electron microscopy showed that the material under study was not dinosaur tissue, but bacterial biofilms - colonies of bacteria linked together by polysaccharides, proteins and DNA. These two things look quite similar, but have more in common with dental plaque than with dinosaur cells.
In any case, these findings were very interesting. Perhaps the most interesting thing we haven't found yet. The scientists perfected their techniques and, when they got to the lufengosaurus nest, they braced themselves. Captivating? Absolutely. Organic? Yes. DNA? No.
But what if it's possible?
there is hope
Over the past ten years, advances in stem cells, ancient DNA resuscitation, and genome restoration have brought the concept of “reverse extinction” closer to reality. However, how close and what this might mean for the most ancient animals is still unclear.
Using frozen cells, scientists successfully cloned a Pyrenean ibex known as a bucardo in 2003, but it died within minutes. For years, Australian researchers have been trying to bring back to life a southern species of mouth-feeding frog, the last of which died decades ago, but their venture has so far been unsuccessful.
This is how, stumbling and cursing at every step, scientists give us hope for more ambitious resuscitations: mammoths, passenger pigeons and Yukon horses, which became extinct 70 thousand years ago. This age may be confusing at first, but just imagine: that's one-tenth of a percent of the time the last dinosaur died.
Even if dinosaur DNA were as old as yesterday's yogurt, numerous ethical and practical considerations would leave only the craziest of scientists among those who would support the idea of resurrecting dinosaurs. How are we going to regulate these processes? Who will do this? How will resurrecting dinosaurs affect the Endangered Species Act? What will failed attempts bring, besides pain and suffering? What if we resuscitate deadly diseases? What if invasive species grow on steroids?
Of course, there is growth potential. Like the representation of wolves in Yellowstone Park, a “rollback” of recently extinct species could restore balance to disturbed ecosystems. Some believe that humanity owes a debt to the animals it has destroyed.
The DNA problem, for now, is a purely academic issue. It is clear that resurrecting some frozen baby mammoth from a frozen cage may not arouse much suspicion, but what to do with dinosaurs? The discovery of a Lufengosaurus nest may be the closest we've ever gotten to Jurassic Park.
As an alternative, you can try to crossbreed an extinct animal with a living one. In 1945, some German breeders claimed that they were able to revive the aurochs, the long-extinct ancestor of modern cattle, but scientists still do not believe this event.
I think everyone has heard about the Jurassic Park film series. For some, the original trilogy is warm memories from childhood, while others prefer the new films. And there is something passionate and inspiring about these largest, fiercest, and “dead” creatures to ever walk our planet.
And, probably, a sufficient number of people wondered - is it really possible to clone or in any other way revive dinosaurs, as shown in the films? The "Mr. DNA" sequence in the original film is a great visualization, and the very concept of extracting DNA from mosquitoes that drank dinosaur blood and then froze in amber seems quite workable. However, this is just a beautiful fiction.
Quite by accident, we recently determined the overall genomic structure of dinosaurs (using the genomes of living dinosaur "relatives" - birds and turtles). Genomic structure is the way genes are arranged on the chromosomes in each species. Although individual animals of the same species will have different DNA sequences, the overall genomic structure is species specific.
Scientists began by working out the most likely genomic structure of the "bird-turtle" ancestor, before tracking any changes that occurred between then and now. This lineage begins with the emergence of dinosaurs and pterosaurs ~240 million years ago, through theropods (which includes tyrannosaurs and velociraptors), and ends with birds.
Although we have not made any claims about the extraction of dinosaur DNA, the question that I want to ask after reading the material above is “is this bringing us closer to the real Jurassic Park?” Unfortunately, the answer is a resounding no, and here's why.
First, the idea of extracting dinosaur DNA contained within blood-sucking insects preserved in amber simply doesn't work in practice. Prehistoric mosquitoes with dinosaur blood have been discovered, but any DNA has long since degraded. Neanderthal and mammoth DNA have been successfully isolated, but dinosaur DNA is too old. The oldest DNA ever found is about a million years old. Considering that dinosaurs lived more than 66 million years ago, there is simply no chance of success.
Second, even if we could extract dinosaur DNA, it would be chopped into millions of tiny pieces, and we have little idea how those pieces are supposed to be organized. It would be like trying to put together the world's hardest puzzle without knowing what the final object looks like or if there are any missing pieces.
Unfortunately, it is not possible to grow a velociraptor in a chicken egg. And in ostrich too.
In Jurassic Park, scientists find these missing parts and take them from the frog genome, but that won't give you a dinosaur, it will give you a hybrid or a "frogsaurus". These pieces of frog DNA can have all sorts of negative effects on the developing embryo. It would make more sense to use birds rather than frogs since they are more closely related (but that still wouldn't work).
Third, if you think you'll get a genome and - bingo - be able to recreate a whole animal, then you're wrong again. DNA is the starting point, but the development of the animal inside the egg is a complex dance of genes turning on and off at the right times under certain conditions.
In short, you need the perfect dinosaur egg and all the complex chemistry contained within it. In the book, scientists create artificial eggs; in the films, ostrich eggs are used. None of these methods will work, you can't "put" chicken DNA inside an ostrich egg and hope to get a chicken (people have tried). The same can be said about velociraptors.
And this despite the fact that we do not touch upon ethical standards, obtaining permission for experiments and calculating the impact on the ecosystem.
So we can't resurrect the dinosaur, but...
Dinosaurs never went extinct. On the contrary, they are now among us. Birds did not evolve from dinosaurs, and birds were not closely related to dinosaurs. Birds are dinosaurs.
Dinosaurs (including birds) have been the victims of at least four mass extinctions, after which they have been reborn in new, increasingly diverse and strange forms. One of the key elements of our paper is that we theorize that their ability to do this is facilitated by their genome structure. Scientists discovered that birds and most non-avian dinosaurs shared many chromosomes (packets of DNA), allowing them to create the wide variety of variations that drive natural selection.
However, looking further ahead, it is possible that in the future Jurassic Park technology could be used to help undo some of the harm caused by humans. Humanity is responsible for the extinction of such famous dinosaur birds as the dodo and the passenger pigeon. Recovering their DNA, which is only a few centuries old, is a much more realistic goal. It's also possible that the eggs of closely related living species might be suitable for injecting DNA from extinct species into them, and under the right conditions we could use them to resurrect some "almost" dinosaurs.
Released on big screens in June, raising a new round of questions among curious viewers about its scientific credibility. Is it possible to resurrect dinosaurs using the method described by science fiction writers?
This question was answered in a column for The Conversation answered Darren Griffin, professor of genetics at the University of Kent.
How dinosaurs were cloned in Jurassic Park
“First, the idea that intact dinosaur DNA would be preserved inside blood-sucking insects frozen in amber is simply incongruous,” Griffin writes. — Prehistoric mosquitoes that drank the blood of dinosaurs have actually been found. But the DNA contained in this blood has long since degraded.
Unlike Neanderthals and woolly mammoths, whose DNA has been successfully isolated, dinosaurs are too ancient. The oldest DNA ever discovered is only about a million years old. But to get dinosaur DNA, we'd have to go back at least 66 million years.
Second, even if we could extract dinosaur DNA, it would be chopped up into millions of tiny particles, and we would have no idea how to organize them. It would be like trying to put together the most complex puzzle in the world without knowing what the original image looks like or how many pieces it should contain.
In Jurassic Park, scientists find these missing fragments and fill them in with frog DNA. But that won't give you a dinosaur. This will produce a hybrid or "frogsaurus". It would also make more sense to use bird DNA since they are more closely related to dinosaurs (though that still wouldn't work).
Third, the idea that all it takes to restore an animal is a twist of DNA—science fiction. DNA is the starting point, but the development of the animal inside the egg is a complex dance of genes switching on and off at the right time.
In short, you need the perfect dinosaur egg and all the complex chemistry it contains. In the book, scientists produce artificial eggs; in the films, they use ostrich eggs. None of these methods will work. You can't put chicken DNA inside an ostrich egg and get a chicken (and people have tried). The same can be said about Velociraptor."
The geneticist crushes the dreams of naive fans of the science fiction franchise, but emphasizes that in the future such technology can be used to compensate for some of the harm caused to animals by people.
“Humanity has seen the disappearance of birds - the dodo and the passenger pigeon. Recovering their DNA, which is only a few hundred years old, is a much more realistic proposal. It's also possible that the eggs of living genetically related species will provide a good enough environment that we use them to resurrect extinct animals."
Genetic engineering is one of the most revolutionary sciences. Scientists are still discussing its possible ban. And while they are arguing, the cloning process is successfully underway in scientific laboratories. Everyone is interested in knowing how things are going with dinosaur cloning.
There is a dubious theory according to which the DNA of a dinosaur can be isolated from the blood of a female mosquito that bit it. This insect is supposedly preserved in amber. This dinosaur clone successfully appeared in the film Jurassic Park.
Of course, it is unlikely to find such a mosquito that bit a pangolin a second ago and immediately fell into a drop of pine resin. It is also highly doubtful that dinosaur DNA in its pure form could be preserved in amber. The hypothesis itself leads to only one conclusion - DNA must be searched for or somehow recreated, but how exactly is still difficult to say.
Almost all Scientific minds are very skeptical about the possibility of finding dinosaur DNA. They give the following reasons: 1. Over the course of 500,000 years, any DNA structure can collapse if it is not exposed to low temperatures. 2.no one has yet managed to find whole DNA; these are always short pieces of a chain that cannot be connected. 3. The most difficult thing is to sift out the pieces of genetic material we need from foreign DNA that was introduced by chance later or simply belongs to bacteria from the era of life of a given dinosaur.
But when a person has a dream, then “the fairy tale becomes reality.” And the impossible becomes possible.
2010 can be called a breakthrough year in the history of DNA reconstruction. 50-75 thousand years ago, extinct ancient people, the Denisovans, lived on Earth together with the Neanderthals. Paleontologists managed to find the remains of a Denisovan girl. Experts were able to decipher the child’s genetic code, since know-how had been developed before this
— reconstruction of fragments of a DNA molecule consisting of a single chain. This discovery became the basis for further clues to evolutionary development on Earth.
year 2013. another breakthrough! The remains of an ancient horse were found in permafrost. They are 550 - 780 thousand years old. Scientists manage to read this genome.
Then another sensation - specialists manage to decipher the mitochondrial DNA of Heidelberg man. This type of Neanderthal lived approximately 400 thousand years ago. In parallel with this, work is being successfully carried out on the genetic structure of the remains of a bear that lived at the same time. The most surprising thing is that the remains of both man and bear were found not in permafrost, but in a warmer climate. What does this mean? It is possible to clone ancient animals not only from frozen remains, but to expand the area of searching for DNA fragments using a new technique.
This technique, like all ingenious things, is simple. To purify the desired DNA from the presence of foreign DNA, Scientists created a so-called DNA template: gene sequences of 45 nucleotides were taken (longer chains are unlikely to be preserved) with existing mutations that occurred after the death of an individual (certain nucleotide substitutions appear after the death of a cell). Then, after analyzing this piece of genetic material, they found the closest DNA, which made it possible to build the correct chain of genes. This is reminiscent of working on puzzles - the overall picture is there, you just need to put it together correctly in small pieces. The Denisovan genome was best suited for this purpose.
This method only works when there is the following base:
1.successful template for genome reconstruction
2. a sufficient number of DNA chain fragments.
We gain new knowledge and a new template with each new transcript. And we delve into the study of more accurate historical events. But so far all these discoveries are limited by a period of no more than 800,000 years. So what about the dinosaurs that lived on Earth from 225 to 65 million years ago? Over such a long period of time, not a single intact DNA molecule would have been preserved, but even here science does not stop at one place.
In the Chernyshevsky region, scientists discovered fragments of fossilized skin of a dinosaur that lived in the Jurassic Period. Scientists have raised the question of real cloning of dinosaurs. Dozens of news agencies showed interest in Transbaikalia in connection with this discovery. Foreign and Russian Scientists came to the institute and admitted that they had never seen anything like this in their lives.
Cloning, of course, has not yet been put on the conveyor belt, and experiments are still being conducted in private or departmental university laboratories. Russian researchers are now hard at work cloning a mammoth. The mammoth genetic material itself is not very difficult to obtain. Let us remember the baby mammoth Dima, who was found whole. Actually, mammoths lived only a few thousand years ago, so their frozen remains have been found more than once in Siberia. There is evidence that back in the 19th century, Siberian hunters fed their dogs mammoth meat. Of course, making a clone of a mammoth from an entire preserved chain of DNA and good quality protein is not very difficult for specialists.
It's much more difficult to clone a dinosaur. According to Doctor of Geological and Mineralogical Sciences Sofia Sinitsa, the period of DNA decay depends on the conditions under which the remains are found and is 500 thousand years. And we must take into account that dinosaurs went extinct approximately 65 million years ago. But many of them lived 150 million years BC. WELL, HOW DO YOU FIND DINOSAUR DNA? The shelf life of DNA baffles researchers. After all, organic tissue is transformed into minerals over millions of years. In rocks that can be analyzed, it actually does not exist. Sofya Sinitsa places a special emphasis on the fact that nothing works with dinosaur skin, in which organic matter could be preserved, and therefore cloning of dinosaurs will have to be done only after geneticists have successfully cloned a mammoth. The scientist promises that in order to find the source material for cloning lizards, she will “dig up all of Siberia.”
You remember very well from the school curriculum that DNA plays the function of transmitting hereditary information. If one of the researchers can find one single completely preserved cell with a complete set of DNA molecules, then further cloning of an exact copy is simply a matter of technology. For example, take the egg of a modern Komodo dragon, destroy the original DNA, and introduce DNA molecules from any species of dinosaur into the egg. Now you can put the egg in a special incubator and wait for the birth of the little dinosaur.
