Alan William Greenwood was born on 29 June 1897 in Melbourne, Australia. He was educated at Wesley College and entered the University of Melbourne in 1915 to read Chemistry and Biology. After completing his first year, Greenwood volunteered for war service with the Australian Imperial Forces, returning from active service in Palestine in 1919. Greenwood gained his BSc from the University of Melbourne in 1920 and his MSc in 1923. Greenwood got the chance to study abroad when he was nominated by the University of Melbourne for an 1851 Exhibition Scholarship and came over to the UK in 1923. He had originally intended to work on poultry genetics under Reginald Punnett at the University of Cambridge, but James Cossar Ewart (Professor of Natural History at the University of Edinburgh) persuaded him to come to Edinburgh and join the Animal Breeding Research Department, then in its infancy under the directorship of Francis Albert Eley Crew.
It was to be a fortunate decision. Crew aroused in Greenwood some of his own enthusiasm for the fowl as material for experimental research. Crew's paper 'Sex Reversal in the Fowl' decided the direction of Greenwood's research for much of his later career; namely the reproductive physiology of the fowl with reference to the secondary sexual characters and its relation to endocrine activity. Greenwood gained his PhD from the University of Edinburgh in 1925. During World War Two Crew joined up for war service, leaving Greenwood as acting head of the Institute of Animal Genetics (as the Department was known by then) as well as head of the poultry section. Before the War was over Crew took up the Chair of Public Health and Social Medicine, so Greenwood remained at the helm of the Institute effectively until 1947 when Conrad Hal Waddington (1905-1975) was appointed to the University's Buchanan Chair of Animal Genetics and the directorship of the animal genetics section of the newly formed National Animal Breeding and Genetics Research Organisation (NABGRO, later ABRO), housed within the Institute.
At the same time that this new organisation was being created, Greenwood was invited by the Agricultural Research Council to submit a comprehensive programme of poultry research. His proposal that a research institute focused on poultry should be established in Edinburgh was accepted, and in 1947 the ARC Poultry Research Centre (PRC) was created, with Greenwood as director, a position he was to hold until his retirement in 1962. The PRC's buildings were erected in 1949 on lands feued from the University of Edinburgh adjacent to the Institute of Animal Genetics, with an outstation to house larger experiments being built on the Bush Estate. Here they inherited as experimental material the inbred flock of Brown Leghorns which had since 1931 been maintained at the Institute of Animal Genetics without the introduction of fresh blood. The remit of research in the PRC was wide, being concerned with scientific problems of interest to the agricultural industry as well as the science of genetics. Studies encompassed such areas as egg production, heredity, sexual characteristics and environmental factors in development and productivity. The Centre also housed a group of workers supported from the British Empire Cancer Campaign who used the Leghorn flock for research on cancer and allied conditions. Greenwood remained Honorary Director of the BECC Unit after his retirement from the PRC in 1962.
Greenwood travelled widely during the course of his career. In 1927 he made an intensive tour of universities and research laboratories in Poland, thanks to a grant from the Board of Agriculture. In 1931 he was awarded a Fellowship by the Rockefeller Foundation for a year's study in America under L.C Dunn at Columbia and Frank Lillie at Chicago. In 1946 he travelled to the USA and Canada as part of a British delegation of scientists and 'practical men' involved with the poultry industry. He was elected Fellow of the Royal Society of Edinburgh in 1927, and received the Keith Prize (1929-1931) for contributions relating to the biology of the fowl. He was vice-president of the Poultry Association of Great Britain, received the Poultry Industry Award in 1954 and in 1959 was awarded the Fellowship of the Poultry Science Association of America - at that time the only person outside of America to receive this distinction. He was made Commander of the British Empire in 1955.
Greenwood was twice married: firstly to Vera Crockett in 1923, and after Vera's death, to Josephine Peace in 1974. Greenwood died at his home in Edinburgh on 04 May 1981. In 2013, the Roslin Institute named one of its newly-built Conventional Avian Research Units the Alan Greenwood Building.