The Gang of Four achieve malign power during China's Cultural Revolution

Donald Johanson and Tom Gray find an almost complete Australopithecus female skeleton at Hadar in Ethiopia, and nickname her Lucy after the Beatles song Lucy in the Sky with Diamonds

David Attenborough writes and presents Life on Earth, a television series on evolution – the first of his many surveys of natural history

An Islamic revolution forces the Shah, Mohammad Reza Pahlavi, to flee from Iran

Ayatollah Khomeini receives a rapturous welcome on his return to Iran to head the Islamic Revolutionary Committee

The Communist party relinquishes power without bloodshed in Czechoslovakia's Velvet Revolution

The rebel Ethiopian People's Revolutionary Democratic Front (EPRDF), led by Meles Zenawi, takes control in Ethiopia

The Revolutionary United Front, led by Foday Sankoh, attacks Sierra Leone from bases in Liberia

Chen Kaige directs Farewell My Concubine, depicting the devastating effect of the Cultural Revolution on some performers of Peking opera

The fossilized skeleton of an Ardipithecus female, nicknamed Ardi and 4.4 million years old, is found in the Awash valley region of Ethiopia

In referenda held by the new Labour government, Scotland votes conclusively for devolution but Wales is lukewarm

Michael Rogers, in a team led by Sileshi Semaw, discovers the world's oldest known chipped stone tool, at Gona in Ethiopia

The 'Rose Revolution' in Georgia forces the resignation of president Eduard Shevardnadze after rigged elections

The Saffron Revolution begins in protest against the Burmese junta, with Buddhist monks soon taking a leading role but resulting after a few weeks in savage persecution

Demonstrators gather in the streets of Sidi Bouzid as news of Mohamed Bouazizi's action spreads, in a mood that sparks the Tunisian revolution and the 'Arab Spring'

Boeing launches, at the Paris Air Show, the 787-10 Dreamliner – the largest version as yet in a revolutionary series of passenger planes built from composite materials