1866

Gregor Mendel publishes his findings on inheritance in peas and his observation that characters are determined by discrete ‘factors’.

1875

German cytologist Oskar Hertwig (1849–1922) describes the process of fertilization and formation of the zygote.

1879–85

German cytologist Walther Flemming (1843–1905) describes the behaviour of chromosomes during cell division, which he terms ‘mitosis’.

1886

German biologist August Weismann (1834–1914) publishes a theory of continuity of the germ plasm through successive generations.

1887–92

German cytologist Theodor Boveri (1862–1915), Hertwig, and others describe meiosis, confirming Weismann’s prediction of a ‘reduction division’.

1900

Hugo de Vries, German botanist Karl Correns (1894–1933), and Austrian botanist Erich von Tschermak (1871–1962) independently rediscover Mendel’s work.

1903

US cytologist Walter S. Sutton (1877–1916) describes how the behaviour of chromosomes during meiosis explains Mendel’s laws and suggests that genes are located on chromosomes.

1909

Dutch botanist Wilhelm Johannsen (1857–1927) coins the term ‘gene’. Frans-Alfons Janssens describes crossing over.

1910

Thomas Hunt Morgan discovers sex-linked traits in fruit flies.

1913

US geneticist Alfred Sturtevant (1891–1970) publishes the first genetic map—of fruit-fly genes.

1916

US geneticist Calvin Bridges (1889–1938) proves the chromosome theory of heredity.

1927

US geneticist Hermann Müller (1890–1967) demonstrates that X-rays can cause mutations.

1930

British statistician Ronald Fisher (1890–1962) publishes The Genetical Theory of Natural Selection, a key work in neo-Darwinism.

1941

George Beadle and Edward Tatum begin work with nutritional mutants of bread mould, leading to their ‘one gene-one enzyme’ hypothesis.

1944

Oswald Avery and colleagues demonstrate that DNA is the genetic material.

1947

Erwin Chargaff establishes the one-to-one ratio of purine and pyrimidine bases in DNA.

1953

James Watson and Francis Crick propose a molecular structure for DNA.

1960

French biochemists Jacques Monod (1910–76) and François Jacob (1920–2013) introduce the term ‘operon’ for a functionally integrated group of genes.

1961–66

The genetic code is deciphered by US biochemists Marshall Nirenberg (1927–2010), Philip Leder (1934– ), and others.

1972

Paul Berg (1926– ) creates the first recombinant DNA molecule, based on a lambda phage.

1973

First experimental genetic manipulation of a bacterium takes place.

1977

Techniques for sequencing DNA devised by US biochemist Walter Gilbert (1932– ), Frederick Sanger, and colleagues.

1978

Human insulin is produced by genetically engineered bacteria.

1983

US biochemist Kary Mullis (1944–2019) devises the polymerase chain reaction for amplifying DNA.

First transgenic plant is created.

1984

British geneticist Sir Alec Jeffreys (1950– ) develops DNA (or genetic) fingerprinting.

1988

First patent is awarded for a genetically engineered animal—a cancer prone mouse.

Field trials of genetically modified tomatoes take place in the USA. The Human Genome Project begins.

1993

Transgenic sheep are used to produce human proteins in their milk. Genetically modified tomatoes go on sale in the USA.

1997

British geneticist lan Wilmut and colleagues announce the birth of a lamb (‘Dolly’)—the first mammal to be cloned from an adult body cell.

1998

The first complete sequence of a genome for a complex animal, the nematode Caenorhabditis elegans, is published.

1999

Full DNA sequence of human chromosome 22 is published, making it the first human chromosome to be fully sequenced.

2002

Draft sequences of the mouse and rice genomes published.

2003

Human Genome Project completes DNA sequencing of the human genome, 50 years after publication of Watson and Crick’s paper on structure of DNA.

2004

Approval granted in the USA for a microarray-based diagnostic genetic test for use in clinical medicine.

2005

Completion of phase I of the International HapMap Project containing over one million markers of the human genome.

2006

Sequencing of Neanderthal DNA reveals differences with modern humans.

2008

Debut of next-generation DNA sequencing.

2009

Successful gene therapy for X-linked adrenoleukodystrophy using engineered stem cells. First detailed map of the epigenome.

2012

Advent of new genome editing tools TALENS and CRISPR.

2015

First comprehensive map of the human epigenome published.

2016

CRISPR-Cas9 gene editing used to treat a human patient.

2017

Intravenous gene therapy with adeno-associated virus used to insert a new gene in spinal neurons of infants suffering from spinal muscular atrophy 1.