Molecular biologists Francis Crick and James Watson announce their discovery of the double-helix structure of DNA

US environmentist Rachel Carson publishes Silent Spring, an impassioned warning of ecological disaster

Scientists at the US Geological Survey develop the theory of plate tectonics as the explanation of continental drift

Luc Montagnier, at the Pasteur Institute in Paris, discovers a new human retrovirus that he names LAV (later changed to HIV)

Genetic (or DNA) fingerprinting is invented and developed by British geneticist Alec Jeffreys

The Human Genome Project begins in the US Department of Energy, with the aim of sequencing the whole of human DNA

Mad Cow Disease (BSE, or bovine spongiform encephalopathy ) is identified and described in Britain

British primatologist Jane Goodall publishes Through a Window, exposing violence and brutality in chimpanzees

A fatal variant CJD (Creutzfeldt-Jacob disease) is first identified in Britain, linked to BSE but capable of infecting humans

Dolly the Sheep is cloned in an epoch-making experiment at the Roslin Institute in Edinburgh

Chromosome 22 becomes the first human genome to be fully sequenced, at the Sanger Institute in Cambridge, England

A White House ceremony celebrates a full draft of the human genome completed by two rival projects

Leland Hartwel, Paul Nurse and Tim Hunt win the Nobel Prize for their discoveries of key regulators of the cell cycle