Human cloning is the creation of a genetically identical copy of a human. The term is generally used to refer to artificial human cloning, which is the reproduction of human cells and tissue. It does not refer to the natural conception and delivery of identical twins. The possibilities of human cloning have raised controversies. These ethical concerns have prompted several nations to pass laws regarding human cloning.
Two commonly discussed types of human cloning are therapeutic cloning and reproductive cloning.
Therapeutic cloning would involve cloning cells from a human for use in medicine and transplants. It is an active area of research, but is not in medical practice anywhere in the world, as of 2023. Two common methods of therapeutic cloning that are being researched are somatic-cell nuclear transfer and (more recently) pluripotent stem cell induction.
Reproductive cloning would involve making an entire cloned human, instead of just specific cells or tissues.
In somatic cell nuclear transfer (SCNT), the nucleus of a somatic cell is taken from a donor and transplanted into a host egg cell, which had its own genetic material removed previously, making it an enucleated egg. After the donor somatic cell genetic material is transferred into the host oocyte with a micropipette, the somatic cell genetic material is fused with the egg using an electric current. Once the two cells have fused, the new cell can be permitted to grow in a surrogate or artificially. This is the process that was used to successfully clone Dolly the sheep. The technique, now refined, has indicated that it was possible to replicate cells and reestablish pluripotency, or "the potential of an embryonic cell to grow into any one of the numerous different types of mature body cells that make up a complete organism
On July 5, 1996, Dolly the sheep—the first mammal to have been successfully cloned from an adult cell—is born at the Roslin Institute in Scotland.
Originally code-named “6LL3,” the cloned lamb was named after singer and actress Dolly Parton. The name was reportedly suggested by one of the stockmen who assisted with her birth, after he learned that the animal was cloned from a mammary cell. The cells had been taken from the udder of a six-year-old ewe and cultured in a lab using microscopic needles, in a method first used in human fertility treatments in the 1970s. After producing a number of normal eggs, scientists implanted them into surrogate ewes; 148 days later one of them gave birth to Dolly.
Dolly’s birth was announced publicly in February 1997 to a storm of controversy. On one hand, supporters argued that cloning technology can lead to crucial advances in medicine, citing the production of genetically modified animals to be organ donors for humans as well as “therapeutic” cloning, or the process of cloning embryos in order to collect stem cells for use in the development of treatments for degenerative nerve diseases such as Alzheimer’s and Parkinson’s. Some scientists also looked at animal cloning as a possible way to preserve endangered species. On the other hand, detractors saw the new cloning technology as potentially unsafe and unethical, especially when it was applied to what many saw as the logical next step: human cloning.
Over the course of her short life, Dolly was mated to a male sheep named David and eventually gave birth to four lambs. In January 2002 she was found to have arthritis in her hind legs, a diagnosis that raised questions about genetic abnormalities that may have been caused in the cloning process. After suffering from a progressive lung disease, Dolly was put down on February 14, 2003, at the age of six. Her early death raised more questions about the safety of cloning, both animal and human. As for Dolly, the historic sheep was stuffed and is now on display at the National Museum of Scotland in Edinburgh.
After her death The Roslin Institute donated Dolly’s body to the National Museum of Scotland in Edinburgh, where she has become one of the museum’s most popular exhibits. Dolly is back on display in the museum after an extensive gallery refurbishment, alongside an interactive exhibit on the ethics of creating transgenic animals featuring current research from The Roslin Institute.
Human cloning is banned across the world because of the following reasons:
It is never ethical to sacrifice one human life to get the potential cells for cloning for the real or potential benefit of others. Research cloning will undoubtedly lead to a new exploitation of women. In order to manufacture enough cloned embryos to create a sufficient number of viable stem cell lines, scientists will need to obtain massive quantities of women's eggs. To do so, women must be injected with super ovulatory drugs and undergo an invasive procedure.
It will create a chaos wherein, people would chose to go for scientifically designed cloned babies and this would eliminate the component of genetic variability.