Disclaimer: The existing claims of (allegedly) successful human cloning experiments are yet to be verified, but the institutes/companies who involved themselves seem to be skeptical about the credibility of their experiments.
Although cloning of non-mammals was first accomplished way back in 1952, the world had to wait for another 44 years before the first mammal was cloned. The birth of first cloned mammal - Dolly the sheep, on 5th July, 1996, established our ability to clone mammalian species.
Considering that we humans are also mammals, the ability of cloning fellow species was undoubtedly an achievement in itself. The jubilation was short-lived though, as the untimely death of Dolly in 2003 turned out to be a major setback and triggered an intense debate on the ethical issues of cloning - a debate which continues even today.
The Practice of Cloning
Cloning is basically a process by which a genetically identical copy of a particular bacteria, plant or animal is produced by means of asexual reproduction. Cloning is not new to the nature; it has existed as a natural process since millions of years.
By definition, a clone is basically a living thing which is made from another - with both sharing the same set of genes. Going by that definition, cloning is also observed in species like the earthworms and salamanders.
When an earthworm is cut into two halves, both grow on to become adult individuals with the same set of genes. Similarly, the birth of identical twins, who share the same set of genes, also demonstrates cloning to a certain extent. These, however, are examples of cloning in nature, which are different from cloning induced by humans.
Important Milestones in the History of Cloning
It was the successful cloning of various animal species, which laid the foundation of various attempts to clone humans - and thus cannot be ignored when we try to trace the history of human cloning research. The practice of cloning can be traced back to 1880s, when many scientists attempted to prove how the genetic material inside the cells worked.
Whilst trying to prove that the genetic material is not lost during cell division, Hans Dreisch cloned sea urchins by separating two cells and growing them independently. In 1902, Hans Spemman repeated the same process with a salamander.
Interestingly enough, there have been quite a few citations about plant cloning in the history. One such example being the cloning of a full carrot by F. C. Stewart in 1964.
First Successful Attempt of Animal Cloning
In 1952, the first successful animal cloning experiment was executed by Robert Briggs and Thomas J. King, wherein they cloned Northern leopard frogs. (Hans Dreisch's cloning of sea urchins was an experiment to prove that the genetic material is not lost during cell division.)
In 1962, John Gurdon used the nucleus of fully differentiated adult intestinal cells, and cloned South African frogs - thus proving that a cell's genetic potential doesn't diminish as the cell specializes. In 1963, the Chinese embryologist Tong Dizhou cloned the first fish, by inserting the DNA from a cell of a male into the egg of a female.
It was in 1963, that the term 'clone', was coined and used for the first time by eminent Scottish biologist - J.B.S. Haldane, in his speech entitled Biological Possibilities for the Human Species of the Next Ten-Thousand Years.
Human Genome - A Step Closer
Other than the successful attempts at cloning of certain animal species, 20th century was also marked by some of the major advancements in the field of genealogy which took us a step closer towards human cloning.
In 1988, the Human Genome, i.e. the genome of Homosapiens stored in 23 chromosome pairs, was launched - 20 years after the successful deciphering of the DNA code which was done in 1968. It came as a major boost for the much-aspired practice of human cloning. Even when animal cloning was in its infancy stage, scientists attempted to clone the human cells.
Dolly the Sheep - First Cloned Mammal
In 1996, Ian Wilmut, Keith Campbell, and fellow scientists from the Roslin Institute, Scotland, were successful in cloning a sheep from an adult somatic cell by the process of nuclear transfer. The lamb, born on 5th July, 1996, was named Dolly, allegedly after American singer Dolly Parton.
The existence of this cloned animal was only made public in February 1997. It was the first time that an attempt to clone a mammal had yielded success. In 1997, scientists pulled off another feat when they successfully cloned monkeys. The two monkeys born as a result of this experiment were named Neti and Ditto.
The successful cloning of primates - who happen to be the human's closest relatives, was another important milestone of the cloning history. Since then several other animals, ranging from cats and dogs to camels and water-buffaloes have been cloned successfully.
Animal Cloning Success - Fact or Myth?
Those in favor of cloning also argued that the practice could help in revival of various endangered and extinct species. In 2001, the scientists at Advanced Cell Technology, Inc. achieved success in their attempt to clone an endangered Asian oxen - the first endangered species to be cloned on the planet.
Sadly though, the newborn died within 48 hours of its birth, and the company was quick to retort that the death of this animal was due to infection which was not related to the process of cloning. Dolly the sheep went on to live for six years, before it succumbed to a progressive lung disease in 2003.
In 2009, the Pyrenean Ibex, which had become extinct in June, 2000, was cloned successfully, but it only survived for 7 minutes and the species became extinct once again. With all these examples, the question whether the practice of animal cloning has really been successful remains unanswered as yet.
Alleged Claims of Human Cloning
In 2002, Clonaid - a human cloning company founded in 1997, revealed that it had successfully cloned humans, and made public a picture of a baby which was allegedly the first clone human, named Eve.
The company followed up with more of such revelations, but it was difficult to assess the credibility of these claims as they refused to undergo a DNA test of the mother and child. More of such claims also surfaced, though none were credible enough.
Human Cloning Prohibition Act
Just when things were falling in place and we were close to the development of a human clone, a major setback came in the form of the Human Cloning Prohibition Act of 2009, which deemed cloning unlawful, unethical and an immoral activity.
The opposition to cloning of humans came from scientific community, which was not satisfied with the results of animal cloning, and the religious communities, which believe that the cloning of humans is an activity which interferes with human life and procreation.
Due to the much-debated ethical issues of cloning, both reproductive cloning and therapeutic cloning are opposed, and even banned in some countries. The scientists are hoping that human cloning will be legalized soon. Many experiments of animal cloning has been done and each of these has put humans one step towards the goal of cloning its own kind.