1966: The complete genetic code is established.

1977: Scientists claim to have created mice with only one parent.

1981: Two scientist 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.

1984: 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 eventually use his method to "twin" cattle, pigs, goats, rabbits and rhesus monkeys.

1986: Scientists clone a cow from embryo cells.

1995: Using differentiated cells from sheep, scientists put embryo cells into an inactive state before transferring their nuclei to sheep eggs. The eggs develop into normal lambs.

JULY 5, 1996: Dolly, a sheep who is the first organism ever cloned from adult cells, is born.

MARCH 4, 1997: President Clinton proposes a five year moratorium on federal and privately funded human cloning research.

JULY 1997: The scientists who created Dolly create Polly, a Poll Dorset lamb cloned from skin cells grown in a lab and genetically altered to contain a human gene.

SEPTEMBER 1997: Thousands of biologists and physicians sign a voluntary five-year moratorium on human cloning in the United States.

JANUARY 1998: Nineteen European nations sign a ban on human cloning.

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.

MARCH 2000: The group that created Dolly 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.

2004: A South Korean scientist makes headlines for using cloning technology to make human embryos. His finding is later determined to be fraudulent.

(THINKQUEST EDUCATION FOUNDATION)