1980
U.S. Supreme Court rules live, human made organisms are patentable material.
1981
Karl Illmensee and Peter Hoppe claim to have cloned mice by transplanting the nuclei of mouse embryo cells into mouse eggs. Other scientists are unable to reproduce the results. It is later discovered that the results were faked.
1983
Kary B. Mullis develops the polymerase chain reaction technique for rapid DNA synthesis.
1983
Solter and McGrath fuse a mouse embryo cell with an egg without a nucleus, but fail to clone using their technique.
1984
Steen Willadsen, a Danish scientist, reports he has made a genetic copy of a lamb from early sheep embryo cells, a process now called "twinning." Other scientists will eventually use his method to "twin" cattle, pigs, goats, rabbits and rhesus monkeys.
1985
Steen Willadsen joins Grenada Genetics to commercially clone cattle.
1986
Steen Willadsen clones cattle from differentiated cells.
1986
First, Prather, and Eyestone clone a cow from embryo cells.
1990
Human Genome Project begins
1994
Neal First produces genetic copies of calves from embryos. They grow to at least 120 cells.
1995
Ian Wilmut replicates First's experiment with differentiated cells from sheep, but puts embryo cells into an inactive state before transferring their nuclei to sheep eggs. The eggs develop into normal lambs.
1996
Dolly, the first animal cloned from adult cells, is born. (not announced until 1997)
February 1997
Wilmut and colleagues at the Roslin Institute in Scotland report they have cloned a 6-year-old adult sheep from an udder cell. They name the sheep Dolly (after Dolly Parton). It is the first clone created from an adult cell.
1997
President Bill Clinton proposes a five year moratorium on cloning.
March 1997
Only a week after the Dolly announcement, scientists bring cloning technology closer to humans by twinning rhesus monkeys from embryos.
March 1997
Scientists and ethicists testifying at a Senate hearing on cloning urge Congress not to rush to ban research on the cloning of human beings.
June 1997
President Clinton signs a five-year moratorium on the use of federal funds for human cloning research. His National Bioethics Advisory Commission had concluded that human cloning would be unsafe and unethical.
July 1997
The scientists who produced Dolly announce they have created a lamb with a human gene in every cell of its body. Named Polly, the lamb was produced using a method similar to that used to create Dolly.
1997
Richard Seed announces his plans to clone a human.
July 1998
Ryuzo Yanagimachi and his postdoctoral student Teruhiko Wakayama in Hawaii clone some 50 mice from an adult cell. Some of the mice are clones of clones, created by using a technique different than that used to produce Dolly the sheep.
December 1998
Japanese scientists report they have cloned eight copies of a single cow, the third mammal to be cloned.
January 2000
Britain becomes the first country to grant a patent for cloned early-stage human embryos. Geron Corporation, which received the patent, says is has no intention of creating cloned humans.
March 2000
The group that created Dolly the sheep announces the first cloned pigs. Scientists hope that pigs could be genetically engineered for use in human organ transplants.
January 2001
An endangered Asian ox called a gaur dies two days after birth of an ordinary disease after it was cloned and gestated in the womb of a cow.