George Malcolm Thomson, born on 2 October 1848 at Calcutta, India, was the son of Margaret Justin Pratt and her husband, William Thomson, a Scottish mercantile trader, tea planter and company owner. George was educated in Edinburgh, where, at 15, he studied chemistry and botany for a year at the University of Edinburgh. He left to help his father establish a merchant office in London, but when the business failed with the collapse of the Agra Bank the family emigrated to New Zealand. They arrived at Campbelltown (Bluff) on the Maria in 1868.
After three years farming unsuccessfully in Southland the Thomsons moved to Dunedin. In 1871 George became a tutor at the High School of Otago (later Otago Boys' High School), and the following year was made junior master. From 1877 to 1903 he was science master at the school. He also taught music and chemistry at the Girls' Provincial School (Otago Girls' High School), and there met Emma Allan, a pupil, whom he married at Hopehill, North Taieri, on 26 December 1876. They were to have four sons and two daughters.
At school Thomson organised nature excursions, a cadet corps, fives and rugby. He played a leading role in the establishment of rugby in Dunedin, arranging the first public football match between the university and the high school in 1871, and subsequently founding the Dunedin Club and the High School Club. In 1882 he was accidentally shot in the foot during cadet corps practice; his foot was amputated 11 years later. Nursing George, along with arduous domestic duties, may have contributed to Emma Thomson's death, at 41, on 21 July 1894, from tuberculosis.
Thomson was a stalwart of Knox Church: a precentor, deacon, elder, Bible-class teacher and stand-in organist. Practical Christianity inspired all his activities, and solaced grief. Three of his children died young: a daughter in infancy, his second daughter of tuberculosis at 20, and a son in France in 1918. On 30 May 1910 George Thomson married Alice Crawford Craig, 25 years his junior, at Melbourne; she died there less than a year later, on 21 January 1911.
Thomson's Christian faith and his educational interests combined in his work for the Young Men's Christian Association, of which he was president for many years, and the Dunedin City Mission, which taught Bible classes in primary schools; he chaired the founding meeting of the mission in 1896. Concern for teenagers lacking secondary education led Thomson to form the Dunedin Technical Classes Association in 1888, inaugurating eight night classes on 24 April 1889. In 1892 the government subsidised classes in 15 subjects which, at Thomson's insistence, were scientific and literary as well as manual. Other towns followed Dunedin's lead, with technical education associations being established in a number of places in the 1890s. In 1913 Thomson opened King Edward Technical College, and he helped establish Columba College (a Presbyterian school for girls), the Dunedin Free Kindergarten Association, and Workers' Educational Association classes in the city. He also had a strong interest in music, being a member of the Dunedin Choral Society from the 1870s.
As a scientist Thomson made his mark not only as a teacher but as a prolific writer, a member of numerous local scientific bodies, and in his major contribution to the institutional reform of science in New Zealand. He became a fellow of the Linnean Society of London and of the Royal Societies of Tasmania and Edinburgh, and held offices in the Australasian Association for the Advancement of Science and the New Zealand Institute, of which he was three times president. Between 1875 and 1933 he published 375 scientific papers and articles, mainly on plants, crustaceans, fish and fisheries. F. W. Hutton, the Otago provincial geologist, persuaded him to study small crustaceans, and Thomson and Charles Chilton became authorities. In 1892 a special taxonomical order was created for one of Thomson's crustacean discoveries, Anaspides. He also published several scientific monographs. His major work, The naturalisation of plants and animals in New Zealand (1922), described over 1,200 introduced species.
In 1895 Thomson proposed that the government, the Otago Institute and the Otago Acclimatisation Society jointly fund a marine research station. Negotiations delayed building, near Portobello on the Otago Peninsula, until 1902. The following year Thomson resigned from teaching to become a consultant and analytical chemist. He chaired the board of the Portobello fish-hatchery, worked in the laboratory, accumulated and catalogued a library and corresponded with hatcheries worldwide. Acclimatisation experiments failed but valuable local studies were initiated. For this work he was awarded the Hector Medal by the New Zealand Institute.
Disillusionment with the dominance of the New Zealand Institute by James Hector, its manager and the director of the Geological Survey and Colonial Museum, had led Thomson to launch a quarterly, the New Zealand Journal of Science, in 1882. Although the journal survived for only a few years, criticism by Thomson and other scientists such as Hutton led to the New Zealand Institute being separated from government scientific bodies, and control of the institute transferred to its incorporated societies. From 1895 a period of 'Thomson reform' saw George, later joined by his son Allan – a distinguished geologist and palaeontologist, and from 1914 director of the Dominion Museum – play a major role in establishing the pattern of government scientific institutions, and in paving the way for the establishment of the Department of Scientific and Industrial Research in 1926. George Thomson entered Parliament for Dunedin North in 1908 as a supporter of W. F. Massey, and as scientific spokesman in the House he initiated the establishment of the Board of Science and Art in 1913.
Although denied the education portfolio, Thomson vigorously promoted education as well as science in Parliament, before losing his seat in 1914. From 1918 to 1932 he served on the Legislative Council. George Thomson died at Dunedin on 25 August 1933. Through his public spirit and diverse talents he had contributed greatly to Dunedin and New Zealand in the fields of science, education and politics.