Cloning refers to a genetically homogeneous group of organisms produced through asexual reproduction, that is, individuals with exactly the same genetic composition of a group of cells or organisms. Now it refers to asexual proliferation at different levels such as individuals, cells, genes, etc.

In 1938, the first modern embryologist, Hans ? Dr. Spieman suggested mammalian cloning using mature nuclei implanted into eggs.

In 1952, using Spielman's concept, the world's first cloned frog appeared.

In 1962, John? Gordon announced that he had cloned a tadpole from a mature cell, sparking the first round of debate about cloning.

In 1984, Steen? Willardson cloned a sheep from embryonic cells. This is the first confirmed case of a cloned mammal.

In October 1995, Dr. Vicanti, an anesthesiologist from Massachusetts in the United States, used modified tissue engineering to grow human ears on the backs of mice, so that humans could grow skin and cartilage that could be transplanted into humans in the laboratory.

In July 1996, the Roslin Institute in Scotland successfully cloned the lamb "Dolly" from sheep mammary cells.

In October 1997, British experts developed a headless frog embryo that could be used to make human organs for medical transplantation.

In July 1999, Japanese scientists cloned a number of cows and put their meat on the market for sale.

In April 2000, Advanced Cell Engineering of the United States cloned six calves younger than their actual age.

In 2000, American scientists successfully cloned a monkey "Tetra" using asexual reproduction technology, which means that there is no technical obstacle to cloning human beings.

On November 25, 2001, a biotechnology company in Massachusetts, USA, successfully cloned human embryos, marking an important step forward in cloning technology.

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