Dolly the sheep only has mothers. She is a cloned sheep that was created and born 20 years ago in a laboratory in Scotland. What is cloning? What are the dangers and moral questions it poses? And why is this a scientific breakthrough after all?
Written by: Ariel Keres, young Galileo
When I was a child I read about cloning in science fiction books, and then I saw movies that dealt with cloning - such as "Blade Runner" or "Jurassic Park", which was released in 1993. Artificial cloning - or Cloning in English - is the creation of an entire animal from one cell, while using its DNA. Who would have believed that this could also happen in reality.
Unlike other things I read about in science fiction books or saw in movies, such as flying cars or spaceships that fly at the speed of light, artificial cloning became a reality almost 20 years ago. In the summer of 1996, Dolly the sheep was born. Although she was not the first cloned creature because she was preceded by frogs that were successfully cloned back in 1952 by the American researcher Thomas King, but Dolly, who was created by the Scottish researchers Ioin Wilmot and Keith Campbell, was the first mammal that was successfully cloned. Dolly was created in the laboratory from an udder tissue cell, in a technique called "cloning by somatic cell nuclear transfer" (a somatic cell is a cell that is not a reproductive cell).
In artificial cloning, processes are carried out that end up with copies of DNA sequences, cells, tissues or organisms that are completely identical - or almost completely - to the source from which they were created. Cloning is not a new process - nature invented it billions of years ago. It occurs every day in asexual reproduction, for example that of unicellular organisms such as bacteria, algae and fungi. Natural cloning also occurs in a process called virgin reproduction. There are plants and also certain animals such as molluscs, insects, reptiles and fish whose females are able to create an embryo without fertilization. Man became jealous of nature and began to develop cloning techniques for creatures in which virgin reproduction does not occur in nature.
Dolly's life
Dolly the sheep was born on July 5, 1996 and died on February 14, 2003. She was cloned at the Rosalind Institute at the University of Edinburgh in Scotland, where she also lived her entire life. The original purpose of the cloning was to produce proteins of medical importance, such as insulin and growth hormone, in the milk of the cloned sheep.
From what you have read so far, you may think that the cloning technology is perfect - but the truth is that most of the cloning attempts made in the Rosalind laboratory failed. Out of 277 fertilized eggs, only 30 were divided. Of these, only nine were taken up in surrogate ewes and led to pregnancy. Only one pregnancy went well, and that's how Dolly the sheep was born. She lived just under seven years (too short a time for sheep), and some scientists claimed that she suffered from accelerated aging because she was a cloned sheep. Dolly gave birth to six patches in her life, and after her death she was rescued. Her stuffed animal is well preserved and currently stands in the Royal Museum of Scotland, in Edinburgh.
The cloning of Dolly the sheep was an extraordinary scientific breakthrough: humanity realized that man could finally "play God" and create creatures himself. Of course, technology has not stopped, and since the cloning of Dolly, other animals have been cloned, such as cats, a cow (2001) and dogs (2005). Lovely Dolly brought to the surface many questions - scientific, philosophical and social. Those in favor of cloning said that now we can save all animals and plants from extinction, and even bring back to the world animals that have become extinct due to human activity - such as the dodo chicken from Mauritius or the Tasmanian wolf. They even contemplate cloning humans; This will allow, for example, infertile people to have children. Another possibility, which is not related to the cloning of Dolly the sheep but to the ability to influence the characteristics of living cells, is the creation of human organs such as a heart or lungs; This will allow doctors to transplant them and save people who have lung cancer, or have had a severe heart attack. Opponents of cloning claimed, among other things, that man is dealing with forces of nature over which he has no control and that cloning may cause dangers that we still cannot imagine.
Is cloning dangerous?
In the "Jurassic Park" movies, cloning is the source of all evil. In the first film, which was released before the cloning of Dolly the sheep, it is told about scientists who managed to clone dinosaurs (herbivores, but also carnivores) from ancient stem cells preserved for 65 million years and resurrect these creatures. The scientists at the Jurassic Park are proud of the fact that they only have female dinosaurs and therefore the dinosaurs in the park cannot reproduce by themselves: their breeding depends on the goodwill of the scientists. But as always happens when man plays with stronger forces than himself in the movies, virgin reproduction comes into play, and the dinosaurs begin to reproduce themselves and become a real danger. The movie "Blade Runner" tells about "replicants" - cloned humans that the human race creates for special purposes, such as doing hard work or fighting. These cloned creatures have a short lifespan of only four years, but they rebel against this sentence.
It is true that there are many arguments against cloning, and many countries have passed laws that limit it, but I think that if we humans can control our instincts, cloning can be of great benefit to us. The possibility of bringing extinct species back to life or saving endangered species gives cloning research strong support. To maintain the possibility of saving extinct species, the huge zoo in San Diego, California, the Commonwealth of Nations, keeps many frozen samples of DNA from endangered species and even extinct species. However, the difficulties, failures and scientific debates for and against cloning have only just begun. Time will tell if in the future cloning will be an everyday matter or if humanity will be forced to give it up because of the many problems and dangers involved.
Why is it so difficult to clone extinct animals?
Prof. Wilmot, who cloned Dolly the sheep, claims that it is possible to clone and bring back to life extinct animals, such as the woolly mammoths that lived here during the Ice Age and whose last remains became extinct only about 4,000 years ago on Varangel Island in Siberia. Well-preserved bodies of mammoths are sometimes found in frozen mud in Siberia, and recently the DNA sequence of the mammoth was restored with the help of these findings. However, in order to clone a mammoth, you first need a large number of eggs of pilots - the animals closest to mammoths. The embryo will have to be implanted in the womb of a female elephant. The chance of this is quite slim, because elephants are also animals that are dwindling. Besides that, after defrosting the whole process should be extremely fast. The transfer of the fetus that will be created to a surrogate mother also involves many difficulties - such a process has not yet been successful in elephants. Prof. Wilmot says that he is not sure that these techniques are possible from a biological point of view, and that there may be unknown differences between biological species, and these will prevent the entire process.
The article was published in the February issue of Young Galileo – Monthly for curious children
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More on the subject on the knowledge site - including real-time reports
- Dolly the Sheep Clan says it will be possible to clone mammoths but it won't be easy
- The "father" of the sheep Dolly is considering whether to continue with the clones
- The meat and milk of cloned animals will reach the supermarket
- Following Dolly's death
- Dolly the sheep has arthritis
- Cloning the sheep
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And exactly 13 years after her death (February 14.2.2003, XNUMX - according to the text in the article)
To clone a mammoth you need an egg and uterus of a mammoth, without that it might be possible to create something that is a hybrid of an elephant and a mammoth but not the original thing. The egg carries part of the DNA inside the mitochondria, information that is not found in other cells and a mammoth's uterus works differently than an elephant's uterus.