With the rapid development of modern technology and technology, many things that have never been heard of before, as if miracles or magic have become a reality, and these emerging technologies have greatly facilitated our daily lives. But just as every coin has two sides, everything has two sides.
While the development of science and technology benefits mankind, it also exposes many drawbacks and potential problems, which are like the sword of Damocles hanging over people's heads, making people always have hidden worries and restlessness.
Among these extremely two-sided science and technology, "cloning" is definitely a very typical example, and I believe that this is a familiar and unfamiliar name for everyone. It is familiar because cloning technology has set off a great boom in the world in the past 20 years, and it has also made the name of the cloned sheep "Dolly" a household name, not to mention the contribution of cloning in literary and artistic works such as science fiction novels, comics and movies.
It is strange because after the "cloning fever" subsided, people's attention to cloning seemed to gradually decline, and related reports and research were correspondingly greatly reduced. People's attention gradually shifted to other areas, and cloning faded from view during these years.
Today, we will revisit the topic of cloning and why "cloning" is rarely mentioned in today's society.
The word "cloning" is derived from the Greek word klōn, meaning "asexual reproduction of plants", so this was first a horticultural word, while the concept of modern cloning was proposed in 1963 by the British geneticist Haldane in a speech, and gradually derived the concept of "replication" over a long period of use.
Cloning is a biotechnology. The process of producing offspring with the same genome as the original individual in artificial or natural asexual reproduction is cloning. Of course, this is only a scientific definition, and the translation into our familiar phrase is probably "to reproduce a life through science and technology".
With the development of experimental embryology and molecular biology, cloning technology has gradually become possible, and the theoretical foundation for cloning is Darwin's "Origin of Species" published in 1859, which shows that the "evolutionary" view shows that animal traits have continuity, which means that cloning technology has a theoretical basis for standing firm.
In 1900, the German biologist Hetovich and Hans Driesch (Hans Driesch) conducted the world's earliest biological cloning experiment, that is, the famous "sea urchin test", after the fertilized egg of the sea urchin split into two cells, they cut open the two germ cells and bred them separately, and finally were surprised to find that each half of the germ developed into two complete individuals, rather than the expected "half a cell can only grow into half an animal".
This discovery also allowed classical genetic theories to be replaced by molecular genetics and promoted the formation of molecular biology in the future.
In the following decades, scholars have conducted a lot of research and experiments around the theory of gene genetics, and the improvement of gene genetic theory has also promoted the birth of cloning technology. Guided by the relevant theories, the German scientist Hans Spemann conducted the first nuclear transplant experiment with the water lizard in 1928 and succeeded, marking the official birth of cloning technology.
In the half a century since, biologists' research on embryology and genetics has entered an unprecedented boom, and after the success of Spemann's water lizard experiment, people wanted to try to clone advanced animals, but due to related theoretical flaws, the first high-level animal, frog cloning results were not ideal.
Later, the research direction of scholars also moved closer to the related field of chemistry, the molecular structure model of double helix DNA became more and more perfect, and the French geneticist Francois Jacob also proposed the theory of gene regulation, which made it possible to clone advanced animals.
First from mice, Xenopus laevis, to cattle and sheep cloned by embryo transfer, and finally there are even many cases of somatic combination of different organisms and IVF. Biologists' research on cloning in full swing has finally come to this point, and one of the major turning points occurred in 1996, when our household name Dolly, the world's first cloned animal obtained from an adult somatic nucleus, was born.
Dolly was the first animal to be cloned from an adult somatic nucleus (the breast cell of an adult ewe), which means that her birth was extraordinary, and it experienced countless failures. According to Ian Wilmut and Keith Campbell, who nurtured Dolly, many embryos were aborted during development due to imperfect technology, and Dolly was the only one of the 277 embryos to develop successfully.
Biologists generally cloned in two ways, an earlier embryo cutting and a nuclear transfer that was dominant at the time. Unlike the embryonic cells used in traditional nuclear transfer, Dolly is cloned using adult somatic nuclei, which breaks through the traditional model of embryonic nuclei and increases the difficulty.
The process is to remove the nucleus of the egg cell, put the nucleus of an individual cell instead, and finally combine it into an embryo-like cell. It doesn't sound too hard, but it's actually very difficult. Because somatic cells have lost their totipotency when they are transplanted, it is difficult to synchronize cell information between donors and vectors.
With such a difficulty, it's no wonder that Dolly was the only survivor of the 277 cases. Its birth proved that humans can clone a specialized cell into a living individual, opening a new page in the history of biological cloning.
Dolly has no mother, or it could be said that it has three mothers.
The first is its genetic mother, a 6-year-old Dorset white-faced sheep from Finland, created by Dolly from her breast cells. The mitochondrial mother and the fertility mother are two different Scottish black-faced sheep, the mitochondrial mother is responsible for providing the eggs, and the fertility mother is responsible for the fertility, and finally successfully gives birth to Dolly.
Dolly's birth shocked the world and meant a lot. Ian Wilmut named the lamb after his beloved famous female singer Dolly Parton. From the day its existence was made public, it received a lot of attention from all over the world.
Dolly's life is not so satisfactory, from childhood to live in a high-intensity monitoring environment, naturally there is no personal freedom, but more importantly, because of the use of "electroconvulsive" method to stimulate egg cell differentiation when carrying out nuclear transplantation at that time, resulting in great damage to the cells. This has a great negative impact on Dolly's health. It has a very poor physique and suffers from many diseases.
In 2001, although Dolly looked like a 4-year-old lamb, she suffered from arthritis like many adult sheep, and the Washington Post in the United States called her "old sheep in lamb clothes", which was enough to see its old age. On February 14, 2003, at the age of 6, Dolly died of lung disease and arthritis. It left behind six children and a cloned sheep specimen.
Many people think that Dolly's life is too short and pitiful, after all, the normal life expectancy of sheep should be around 12-14 years old, and Dolly is less than 7 years old. But Wilmut was amazed at Dolly's "longevity", and in their original expectations Dolly was far from surviving for 6 years. Because almost all previous cloned animals had progeria.
Voices of opposition
We have just learned about the unfortunate Dolly, and now some scholars and the public's negative attitude towards cloning also began with Dolly.
There is no shortage of skepticism about the genetic defects produced by cloning, but the main reason is that it was found that after Dolly, some biologists began to transfer clones to humans.
"Human cloning" sounded absolutely chilling at the time, but from the history of biological cloning, it is not difficult to see the future development trend, and even predicted: from low to high, from germ cells to somatic cells, from fetal to mammalian, and then refined to primates, the fact that the goal of "replicants" as the stage has been very clear. Even as early as 1962, when the British biologist John Gurdon had just successfully cloned Xenopus, scholars discussed with him the prospect of applying cloning technology to humans.
In 2000, the successful cloning of the Ganges short-tailed monkey also meant that the scientific barriers to human cloning had become easily broken, and scholars even said that humans had some genetic advantage, and that cloning humans would have relatively few birth defects compared to cloning animals. The only thing that lies between scholars and research now is the public's attitude towards cloning technology.
The public is certainly not satisfied, and it is not only the public that is speaking out against it, but also the countries behind them. In 1997, after Dolly's publication, American physician Rechard Seed announced his plan to "clone people for profit", and five days after his plan was announced, 19 European countries signed the Agreement on the Prohibition of Cloning in Paris, France, proposing to prohibit the cloning of people with genes similar to the living or the dead in any technology, because it violated ethics and morality, and was more detrimental to human dignity.
A year later, the advent of the first IVF also made the opposition to cloning louder. Hundreds of Americans have demonstrated at the American Academy of Sciences, chanting slogans such as "We don't want to clone." Some religious groups, led by catholics, naturally resist cloning, believing that human beings are not qualified to create and play with life.
In the literary and artistic works (such as novels, movies, etc.) at that time, the image of cloned people also appeared frequently, which enriched people's after-dinner talk and increased people's panic to a certain extent.
Supported sounds
Although it seems insignificant compared with the huge opposition, there were still some people who affirmed the positive significance of cloning at that time, believing that opponents such as "violating ethics" and "genetic defects" were based on "cloning", while ignoring the contribution of cloning technology to fertility, medical treatment and other fields.
On November 27, 2017, China gave birth to the world's first somatic cell cloning monkey "Zhongzhong", and on December 5, the second somatic clone monkey "Huahua" was also born at the Institute of Neuroscience of the Chinese Academy of Sciences.
According to Sun Qiang of the Research Institute, somatic cloned monkeys can produce a large number of model monkeys with the same genetic background within one year, and model creation based on somatic cloned monkey diseases in the future can effectively shorten the drug development cycle of related diseases. The positive impact on modern medicine is immeasurable.
Dolly's birth marks a new chapter in cloning technology, the technology of "cloning people" seems to be the forbidden fruit on the other side of the door, and scholars have the ability to open the door. This has been causing people to think and debate about whether science should have a forbidden area.
Cloning, like all technologies and things, is different in nature, both positive and negative. As the saying goes, blocking is not as good as thinning, in today's rapid development of cloning technology, people's subjective will can not negate the positive significance of science and technology, rather than the overall prohibition or denial, reasonable channeling, so that its natural development may be a better way.