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

Hurricane Patricia becomes the most intense hurricane ever recorded in the Western Hemisphere with winds of 215 mph

A new species of orangutan is identified in Indonesia, becoming the third known species of orangutan as well as the first great ape to be described for almost a century

The world's last male northern white rhinoceros dies in Kenya, making the subspecies functionally extinct

At least 109 people are killed and hundreds wounded by the eruption of Volcán de Fuego, Guatemala's deadliest volcanic eruption in over a century

Victor Vescovo achieves the deepest dive of any human in history as he reaches Challenger Deep within the Mariana Trench, at a depth of 10,928 m (35,853 ft)