Timeline of Cloning History

Dr Ron James of Edinburgh-based scientific research company PPL Therapeutics which developed Dolly, the world's first cloned sheep
Dr Ron James of Edinburgh-based scientific research company PPL Therapeutics which developed Dolly, the world's first cloned sheep. Colin McPherson/Corbis News/Getty Images

Cloning Timeline

  • Theories and Ideas
  • Experiments and Breakthroughs
  • Laws and other writings

1885   August Weismann, professor of zoology and comparative anatomy at the University of Freiberg, theorized that the genetic information of a cell would diminish as the cell went through differentiation.

1888   Wilhelm Roux tested the germ plasm theory for the first time. One cell of a 2-cell frog embryo was destroyed with a hot needle; the result was a half-embryo, supporting Weismann's theory.

1984   Hans Dreisch isolated blastomeres from 2- and 4-cell sea urchin embryos and observed their development into small larvae. These experiments were regarded as refutations of the Weismann-Roux theory.

1901   Hans Spemann split a 2-cell newt embryo into two parts, resulting in the development of two complete larvae.

1902   Walter Sutton published "On the Morphology of the Chromosome Group in Brachyotola magna", hypothesizing that chromosomes carry the inheritance and that they occur in distinct pairs within a cell's nucleus. Sutton also argued that how chromosomes act when sex cells divide was the basis for the Mendelian Law of Heredity.

1902  German embryologist Hans Spemann split a 2-celled salamander embryo and each cell grew to adulthood, providing proof that early embryo cells carry necessary genetic information. This finally disproved Weismann's 1885 theory that the amount of genetic information in cells decreases with each division.

1914   Hans Spermann conducted and early nuclear transfer experiment.

1928   Hans Spemann performed further, successful nuclear transfer experiments.

1938   Hans Spemann published the results of his 1928 primitive nuclear transfer experiments involving salamander embryos in the book "Embryonic Development and Induction." Spemann argued the next step for research should be the cloning organisms by extracting the nucleus of a differentiated cell and putting it into an enucleated egg.

1944   Oswald Avery found that a cell's genetic information was carried in DNA

1950   First successful freezing of bull semen at -79°C for later insemination of cows was accomplished.

1952   First animal cloning: Robert Briggs and Thomas J. King cloned northern leopard frogs.

1953   Francis Crick and James Watson, working at Cambridge's Cavendish Laboratory, discovered the structure of DNA.

1962   Biologist John Gurdon announced that he had cloned South African frogs using the nucleus of fully differentiated adult intestinal cells. This demonstrated that cells' genetic potential do not diminish as the cell became specialized.

1962-65   Robert G. McKinnell, Thomas J. King, and Marie A. Di Berardino produced swimming larvae from enucleated oocytes that had been injected with adult frog kidney carcinoma cell nuclei.

1963   Biologist J.B.S. Haldane coined the term "clone" in a speech entitled "Biological Possibilities for the Human Species of the Next Ten-Thousand Years."

1964   F.C. Steward grew a complete carrot plant from a fully differentiated carrot root cell.

1966   Marshall Niremberg, Heinrich Mathaei, and Severo Ochoa broke the genetic code, discovering what codon sequences specified each of the twenty amino acids.

1966   John B. Gurdon and V. Uehlinger grew adult frogs after injecting tadpole intestinal cell nuclei into enucleated oocytes.

1967   DNA ligase, the enzyme responsible for binding together strands of DNA, was isolated.

1969   James Shapiero and Johnathan Beckwith announced that they had isolated the first gene.

1970   Howard Temin and David Baltimore each independently isolated the first restriction enzyme.

1972   Paul Berg combined the DNA of two different organisms, thus creating the first recombinant DNA molecules.

1973   Stanley Cohen and Herbert Boyer created the first recombinant DNA organism using recombinant DNA techniques pioneered by Paul Berg. Also known as gene splicing, this technique that allows scientists to manipulate the DNA of an organism - the basis of genetic engineering.

1977   Karl Illmensee and Peter Hoppe created mice with only a single parent.

1978   David Rorvik published the novel In His Image: The Cloning of a Man.

1978   Baby Louise, the first child conceived through in vitro fertilization, was born.

1979   Karl Illmensee claimed to have cloned three mice.

1980   In the case Diamond v. Chakrabarty, the United States Supreme Court ruled that a "live, human made microorganism is patentable material."

1983   Kary B. Mullis developed the polymerase chain reaction (PCR) in 1983. This process allows for the rapid synthesis of designated fragments of DNA.

1983   Davor Solter and David McGrath tried to clone mice using their own version of the nuclear transfer method.

1983   The first human mother-to-mother embryo transfer was completed.

1983-86   Marie A. Di Berardino, Nancy H. Orr, and Robert McKinnell transplanted nuclei of adult frog erythrocytes, thus obtained pre-feeding and feeding tadpoles.

1984   Steen Willadsen cloned a sheep from embryo cells, the first verified example of mammal cloning using the process of nuclear transfer.

1985   Steen Willadsen used his cloning technique to duplicate prize cattle embryos.

1985   Ralph Brinster created the first transgenic livestock: pigs that produced human growth hormone.

1986   Using differentiated, one-week old embryo cells, Steen Willadsen cloned a cow.

1986   Artificially inseminated surrogate mother Mary Beth Whitehead gave birth to Baby M. She tried and failed to retain custody.

1986   Neal First, Randal Prather, and Willard Eyestone used early embryo cells to clone a cow.

Oct 1990   The National Institutes of Health officially launched the Human Genome Project to locate the 50,000 to 100,000 genes and sequence the estimated 3 billion nucleotides of the human genome.

1993   M. Sims and N.L. First reported the creation of calves by transfer of nuclei from cultured embryonic cells.

1993   Human embryos were first cloned.

Jul 1995   Ian Wilmut and Keith Campbell used differentiated embryo cells to clone two sheep, named Megan and Morag.

Jul 5, 1996   Dolly, the first organism ever to be cloned from adult cells, was born.

Feb 23, 1997   Scientists at the Roslin Institute in Scotland officially announced the birth of "Dolly"

Mar 4, 1997   President Clinton proposed a five-year moratorium on federal and privately funded human cloning research.

Jul 1997   Ian Wilmut and Keith Campbell, the scientists who created Dolly, also created Polly, a Poll Dorset lamb cloned from skin cells grown in a lab and genetically altered to contain a human gene.

Aug 1997   President Clinton proposed legislation to ban the cloning of humans for at least 5 years.

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

Dec 5, 1997   Richard Seed announced that he intended to clone a human before federal laws could effectively prohibit the process.

Early Jan 1998   Nineteen European nations signed a ban on human cloning.

Jan 20, 1998   The Food and Drug Administration announced that it had authority over human cloning.

Jul 1998   Ryuzo Yanagimachi, Toni Perry, and Teruhiko Wakayama announced that they had cloned 50 mice from adult cells since October, 1997.

Jan 1998   Botechnology firm Perkin-Elmer Corporation announced that it would work with gene sequencing expert J. Craig Venture to privately map the human genome.

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