Is it Possible to Bring Dinosaur Alive
After extracting dinosaur DNA from a mosquito embedded in fossilized resin that had sucked dinosaur blood, a scientist succeeded in creating a replica of the dinosaur that was featured in the movie Jurassic Park. In real life, dinosaurs, which have been extinct for tens of millions of years, touch many people's nerves, people are full of curiosity and desire for it, and even bold scientists want to revive this prehistoric giant.
But a new study by New Zealand scientists suggests it only takes 6.8 million years for DNA to break down completely. Therefore, the media reported that the lifespan of DNA is 6.8 million years, and dinosaurs died out 65 million years ago. The idea of bringing dinosaurs back to life seems to be over. So, are dinosaurs really dead? If so, what would be the difficulty of resurrection? To this end, the reporter interviewed the relevant experts.
Genetic issues
The 6.8 million year "life span" of DNA degradation is not conclusive
A new study from New Zealand suggests it takes just 6.8 million years for DNA to break down completely. They calculated that DNA has a half-life of about 521 years, meaning that the chemical bonds between deoxyribonucleotides break in half every 521 years. And even at -5 degrees, at most 6.8 million years, all of these bonds will break down. And long before that, maybe as little as 1.5 million years ago, the bonds were so broken that they were completely unreadable. Sadly, dinosaurs died out 65 million years ago.
The study isn't conclusive, though. Other researchers have suggested that many other factors, such as soil chemistry, post-excavation storage conditions and even the season of the animal's death, could have influenced the results. Xu Xing, a renowned dinosaur expert and researcher at the Institute of Vertebrate Paleontology and Paleoanthropology under the Chinese Academy of Sciences, said: "As we all know, DNA is a large organic molecule and has no lifespan. It is not very scientific to talk about the lifespan of DNA." He pointed out that large organic molecules such as DNA quickly break down into fragments after the death of an organism because of changes in the environment. These fragments are sometimes preserved in fossils and can be used to study ancient DNA. But reliable pieces of ancient DNA are known to be only a few hundred thousand years old at most, far from the age of the dinosaurs.
Of course, under certain conditions, such as when the DNA is in an environment close to that of the organism itself, that means that the optimal condition, at the slowest rate of decomposition, might take 6.8 million years to break down completely.
"6.8 million years is not a foregone conclusion. It is based on calculations and there is no direct evidence." According to Wang Yingchun, a doctoral supervisor and researcher at the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences, there are many physical, chemical and biological factors that affect the degradation of DNA, such as temperature, the acidity and alkalinity of the environment and the activity of organisms. High temperature and acidity can promote the degradation of DNA, and the DNA enzymes released by microorganisms can easily degrade DNA. Stored in a neutral environment and frozen in liquid nitrogen, it is believed that the lifespan of DNA could be much longer than 6.8 million years. Of course, when the study says 6.8 million years, it refers to the complete degradation of DNA. In fact, the genetic information provided by incomplete DNA is itself incomplete. In this sense, the DNA that can provide complete and true genetic information may have been stored for much less than 6.8 million years.
Reproduction problem
Finding intact DNA is difficult and creating embryos is difficult
Now a large number of dinosaur or dinosaur egg fossils have been found in the world, some people can not help but ask, in so many fossils can not get a complete dinosaur DNA?
"It's not difficult to get complete DNA from living organisms, and you can keep it stable under certain conditions, but it's impossible to get complete DNA from dinosaur fossils." Although Wang ruled out the possibility of obtaining complete dinosaur DNA from fossils, let's take a step back. Suppose scientists get lucky and find enough dinosaur DNA fragments in these fossils, will they ever be able to piece together complete dinosaur DNA?
The answer is very hard. "Even if people do have fossils of some of this DNA, we only have a very small section of the genetic code, not all the key genes. So it's very unlikely that you would be able to replicate a dinosaur using the ancient DNA that remains." Experts believe that the human genome is sequenced by first breaking up the entire genome (because the DNA fragments that are sequenced at a single time cannot be too long) and then reassembling it. But fossils are so long in the tooth, and dinosaurs include so many different species, that it is extremely difficult to guarantee that these few fragments will eventually add up to a complete genome of a dinosaur. Just like a box of jigsaw puzzle as long as you take the time, sooner or later can be put together; But if you have 100 boxes of puzzle pieces mixed together and you just pull out a handful, it's much harder to make a complete picture.
So, if we take a step back and say we can repair the entire DNA of a dinosaur, would we be all right?
Wang believes that with the current knowledge and technology, it is impossible to reproduce a dinosaur embryo, even with a complete set of dinosaur DNA. Existing cloning techniques, including nuclear transfer and stem cell technology, operate at the cellular level, where there must first be viable cells to operate on. DNA is just a chemical molecule containing genetic information. Even if it is introduced into a receptor, such as a nucleated cell, it is difficult to ensure the correct expression of tens of thousands of genes contained on it, because DNA must first be packaged into chromosomes, which must have a series of positive and negative regulatory factors to regulate the expression of genes on it. So far, humans have not been able to package purified DNA from higher organisms into functional chromosomes and nuclei.
Survival issue
The lack of suitable embryonic receptors is not easy to adapt to today's environment
When it comes to bringing back dinosaurs, not all scientists think the road ahead is bleak. "With the development of developmental biology, our understanding of morphological structures and their developmental mechanisms is getting deeper and deeper," Xu said. "If one day we can fully understand how every morphogenetic structure develops, and genetic engineering advances to the point where it can be controlled, then in theory we should be able to make something like a dinosaur."
Now that scientists have given us a glimmer of light, we might as well boldly assume that if humans can create dinosaur embryos, the resurrection of dinosaurs will be just around the corner?
In the movie "Jurassic Park", the small dinosaurs are in the incubator to break out of the shell, but we can't create dinosaur eggs out of thin air, but also must find the right embryo to cultivate the receptor, there will be dinosaur eggs, so, where do we find suitable for dinosaur breeding receptors? Modern large animals, such as elephants, whales and ostriches, also have huge bodies, but if you want to transplant a dinosaur embryo into the body of these animals, can you successfully give birth to a dinosaur?
Chen Dayuan, a researcher at the Institute of Zoology of the Chinese Academy of Sciences, pointed out that because some large dinosaurs gave birth to babies that were also very large, receptors for dinosaur embryos were hard to find. Other large animals, like elephants, were not as big as dinosaurs, and dinosaurs were so far apart from elephants that it was difficult to breed them easily. Of course, not all dinosaurs were giant, and there were species of dinosaurs that looked like chickens that could be used as receptors for modern animals of the same size.
If, assuming all the assumptions are true, scientists first find the complete genetic code of dinosaurs and then find suitable breeding receptors to bring them back to life, could we take Jurassic Park off-screen?
Studies have shown that carbon dioxide concentrations were high in the Mesozoic era, when dinosaurs lived, and low in the Cenozoic era that followed. The adverse factors of this environment to dinosaurs may be reflected in two aspects: first, the dinosaurs' body had developed discomfort, and in the new environment, it was easy to get sick, and the disease would spread like a plague; Second, the new atmosphere was more hospitable to mammals, which became more advanced and adaptable competitors. With the help of these two factors, the dinosaurs eventually died out.
"It's hard to predict whether dinosaurs could survive," Xu said. After all, dinosaurs lived in a very different time than the Earth does today, and many factors like the composition of the atmosphere have changed a lot, so it's hard to say. I think if I can survive, at least I need some time to get used to it."
In addition, there is a continuing debate in academia and society as to whether or not to pursue the study of resurrecting paleontology. Most scientists believe that replicating dinosaurs is theoretically possible, but extremely difficult. If this is a locally controlled laboratory activity, then there is nothing wrong with it as academic research. But if natural processes are artificially altered by copying dinosaurs, as in Jurassic Park, then this is questionable. After all, no one can answer the question of whether we are replicating a real dinosaur or a monster, or how it would react in its present natural environment. In fact, in Jurassic Park, the director has expressed this concern about human interference in natural processes through a number of disastrous scenes. So it's possible that people's dream of Jurassic Park will always be a dream.
