1866	Gregor Mendel, Austrian botanist and monk, proposes basic laws of heredity, based on crossbreeding experiments with pea plants. However this great discovery was ignored for more than 30 years.
1882	German embryologist Walther Fleming spots tiny threads within the cells' nuclei that appear to be dividing, while examining a salamander larvae under a microscope. The threads later turn out to be chromosomes.
1910	U.S. Biologist Thomas Hunt Morgan reveals that some genetically determined traits are sex linked by experiments with fruit flies. His work also confirms that the genes determining these traits reside on chromosomes.
1926	Hermann Muller, an American biologist discovers that X rays can cause genetic mutations in fruit flies.
1944	Oswald Avery and Maclyn McCarty prove that DNA, not protein, is the hereditary material in most living organisms by experiments using pneumococcus bacteria.
1953	American biochemist James Watson and British biophysicist Francis Crick propose the discovery of the double-helix structure of DNA, the molecule that carries the genetic code.
1964	Stanford geneticist Charles Yanofsky and his colleagues prove that the sequence of nucleotides in DNA corresponds exactly to the sequence of amino acid s in proteins.
1970	Researchers of University of Wisconsin synthesize the first gene from scratch.
1973	American biochemists Stanley Cohen and Herbert Boyer insert a gene from an African clawed toad into bacterial DNA, in which its functions appeared. This was the beginning of genetic engineering.
1975	At an international meeting in Asilomar, California, scientists call for guidelines for recombinant-DNA research.
1976	The first genetic engineering company, Genetech, is founded in South San Francisco.
1978	Scientists from Genetech and a medical center of Duarte, California, successfully clone the gene for human insulin.
1980	Researchers introduce a human gene that codes for the protein interferon, into a bacterium.
1980	Martin Cline and his coworkers create a transgenic mouse, transferring the functional genes of an animal to another.
1982	The U.S. Food and Drug Administration approves the first genetically engineered drug, a form of human insulin produced by bacteria.
1983	Researchers locate a genetic marker for Huntington's disease on chromosome 4. Their achievement leads to a screening test, but the disorder remains incurable. The gene itself is found 10 years later.
1983	Kary Mullis, a biochemist at Cetus Corp., conceives of the so-called polymerase cahin reaction, or PCR, a technique that will enable scientists to rapidly reproduce tiny snippets of DNA while driving along a California highway.
1984	Alec Jeffreys of Britain's University of Leicester, develops "genetic fingerprinting," a technique used to identify individuals from one's unique sequences of DNA.
1985	First use of genetic fingerprinting in a criminal investigation.
1986	The FDA approves the first genetically engineered vaccine for humans, hepatitis B.
1988	Harvard University receives the first patent for a genetically altered animal, a mouse highly susceptible to breast cancer.
1989	The National Center for Human Genome Research is founded, headed by James Watson. It presently oversees the $3 billion U.S. effort to map and sequence all human DNA by 2005 (the Human Genome Project).
1990	Formal launch of the International Human Genome Project.
	W. French Anderson, an American geneticist performs the first gene therapy to a four year old girl with an immune-system disorder called ADA deficiency.
1991	Mary-Claire King of the University of California, Berkeley, finds evidence that a gene on chromosome 17 causes the inherited form of breast cancer and also increases the risk of ovarian cancer, by analyzing chromosomes from women in cancer-prone families.
1992	The U.S. Army begins collecting blood and tissue samples from all new recruits as part of a "genetic dog tag" program, aimed for better identification of soldiers killed in combat.
	American and British scientists unveil a technique for testing embryos in vitro for genetic disorders such as cystic fibrosis and hemophilia.
1993	Biochemists at the U.S. National Cancer Institute report that at least one gene related to homosexuality resides on the X chromosome, which is inherited from the mother, by analyzing the family trees of gay men and the DNA of pairs of homosexual brothers.
	George Washington University researchers clone human embryos and nurture them in Petri dish for several days. The project provokes protests from ethical politicians and critics of genetic engineering.
	An international research team of the Center for the Study of Human Polymorphisms in Paris, led by Daniel Cohen, produces a rough map of all 23 pairs of human chromosomes.
1995	Researchers at Duke University Medical Center in Durham, North Carolina report that they have transplanted hearts from genetically altered pigs into baboons. All three transgenic hearts survived at least a few hours, proving cross-species operations to be possible.
1997	Researchers at Scotland's Roslin Institute, led by embryologist Ian Wilmut, report that they have cloned a sheep named Dolly from the cell of an adult ewe.
1998	Scientists of the University of Hawaii, clone a mouse using a variation of Wilmut's technique, creating not only dozens of copies but three generations of cloned clones.
	Two research teams succeed in growing embryonic stem cells.
	Scientists at Japan's Kinki University clone eight identical calves using cells taken from a single adult cow.