Dolly, the first cloned animal to be born in 30 years was one of science’s most celebrated animals.
She sparked speculation about a future sci-fi filled with cloned animals, cloned people and even extinct species like the woolly Mammoth. Cloning is a complex process.
Cloning today is not just a way to “copy-and-paste” things. It has instead become just one of many biotechnology tools.
Scientists can use it to better understand disease, conserve the environment and create new ways of manipulating living organisms.
The team responsible for cloning Dolly was led by Ian Wilmut, geneticist at the Roslin institute, who is pictured with her on April 9, 2003. Maurice McDonald/AP
Cloning is a real process
The majority of animal cloning takes place using the technique known as somatic nuclear transfer.
In this technique, the nucleus of a cell that is not reproductive (i.e., it isn’t a sperm, egg, or ovum) from a living animal is removed. The donor cell in the case of Dolly came from the mammary gland.
The nucleus of the egg will also be removed.
With the aid of an electrical pulse, the nucleus is implanted into the egg. The fused embryo is then implanted in the uterus of a surrogate.
It is almost identical to the donor animal in terms of DNA.
Dolly’s cloning was achieved using somatic nucleus transfers.
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Why cloning remains difficult decades later
Cloning mammal remains inefficient despite technological advances. Many reconstructed eggs may not develop for every successful clone. Dolly, for example, took 277 attempts. Cloning is expensive, and requires special equipment, donated cells, surrogate pregnancy, and egg cells.
It isn’t about copying DNA that the biggest challenge lies.
The genes are not the only thing that makes an organism different. The environment, experiences and development also affect how animals grow and behave. The hard part of this is convincing a cell that has specialised in its own job, like the mammary cells, to forget about it and act as an embryo.
It is called epigenetic programming. It is necessary to reset chemical instructions in the egg cell that determine which genes will be switched on and off. The reset can be incomplete. This is the reason why so many cloned eggs do not develop properly.
Another major breakthrough was made by cloning research. Scientists found that they could reprogram cells to become induced pluripotent cells.
They are similar to embryonic stem cell behavior, but they aren’t used for the creation of an entire organism. They can instead be transformed into different types of cells.
Researchers have been able to use these cells in order to test drugs, study disease and investigate regenerative medicine.
Cloning studies have shown that cells can be “rewritten” biologically.
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The stem cells that you use to create your own embryos are not the same. What you should know
Cloning is used in other places today.
Cloning is used by some livestock industries to produce animals that have valuable traits such as high genetic diversity, productivity, or resistance to disease.
Cloning does not replace traditional breeding. It allows for the reproduction of desirable animals.
It’s possible to clone horses in Australia, and many famous clones competed in international equestrian events.
China and the United States are two countries that offer pet cloning services for dogs and cats. Broadway’s Barbra Streisand famously had Samantha, her dog of choice, cloned to produce two puppies.
The new clones had different personalities from the original because the only thing they shared was DNA, not experiences or memories.
Researchers in China, in 2024, cloned the first rhesus monk in history, due to its physiological similarities with humans. It was hoped that this would accelerate drug testing. Animal welfare activists raised concerns about these experiments. They questioned whether animal suffering would be worth it given the lack of success and immediate practical applications.
Cloning can be used to help restore populations of threatened species. Scientists cloned the black-footed Ferret in 2020 using preserved genetic material from an animal who had died many decades before.
This project was designed to boost genetic diversity of a species that is experiencing severe population declines in the US.
Elizabeth Ann is the first black-footed cloned ferret bred in the US. Wikimedia Commons
Can cloning bring extinct species back?
Public imagination has been captured by the idea of bringing extinct species back, but scientific reality makes it much more difficult.
For a true clone, you need an intact genome and the egg cells of a species that is closely related. This isn’t possible for animals who died thousands of years before, like the woolly Mammoth. The ancient DNA has been damaged.
Researchers are instead exploring ways to reverse species extinction (also known as deextinction), combining ancient DNA research and gene editing technologies like CRISPR.
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CRISPR is the technology for gene editing that has won the Chemistry Nobel Prize.
Scientists are trying to bring back extinct traits in living animals, rather than recreate an exact replica of an extinct species.
A future mammoth would be likely an elephant edited to look like one, and not the real thing.
The scientists also warn that the return of extinct traits does not automatically recreate an extinct species’ ecological role. The ecosystems in which animals live may not exist as they were before.
Cloning is a great way to restore genes lost in populations that are endangered, but producing too many animals with similar genetics could make them more susceptible to diseases.
Human cloning is not an option
Human cloning is not a reality despite decades of speculation.
Safety is the main obstacle. The main barrier is safety. Animal cloning has a high rate of failure, but applying it to humans will create unacceptable risks.
Also, there are major ethical issues, such as questions of consent, identity and possible exploitations of human tissue and reproductive technology. In many countries including Australia, the practice of reproductive human cloning has been banned or severely restricted.
Dolly’s cloning 30 years ago has helped improve disease research, agricultural practices, and conservation.
Cloning remains a tricky process, which continues to raise concerns about safety and regulation, as well as whether certain applications of cloning should even be pursued.
