Arthur Saunders Thomson is said to have been born on 29 December 1816, and was baptised on 2 January 1817 at Arbroath, Angus, Scotland. He was the son of Margaret Saunders and her husband, James Thomson. Arthur Thomson studied at the University of Edinburgh, where he developed an interest in the relationship between climate, environment and disease. Graduating with an MD in 1837, he won a gold medal from the Edinburgh medical faculty for his thesis on the worldwide influence of climate on health and morbidity. A year later he published a statistical paper on fever in Great Britain. Using vital and hospital statistics, a method of analysis which was still relatively new, Thomson argued that the incidence of fever had been declining throughout the eighteenth century. However, a suggestion that the medical treatment of the day was successful in reducing the intensity and mortality of fever was less tenable.
In October 1838 Thomson joined the British Army as an assistant surgeon. He was stationed at Bombay, India, with the 17th (Leicestershire) Regiment of Foot until 1842 and then with the 14th King's Light Dragoons. While in India, Thomson wrote about a serious epidemic of fever among the 17th Regiment in the Colabah barracks during the 1841 monsoon. Returning to England on leave in 1847, he was appointed surgeon to the 58th (Rutlandshire) Regiment of Foot, and proceeded to New Zealand.
The transfer was fortunate. New Zealand's northern war was over, and the unsettling influence of Te Rauparaha had been undermined. For the following decade the British Army played a deterrent role only, while settlement increased and British sovereignty was extended over the whole of the South Island and much of the North. Untroubled by the medical duties which accompanied both war and pestilence, Thomson was free to observe and to write. In the 1850s he published a number of scientific and medical papers which applied his interest in statistics and climatology to New Zealand conditions.
The contrast between fever-ridden India and the antipodes was dramatic for an observer already committed to exploring comparative rates of illness. In an article published in the Edinburgh Medical and Surgical Journal in 1850, Thomson demonstrated that the rates of morbidity and mortality among British soldiers in New Zealand were dramatically lower than in India, and were even a significant improvement on British statistics. Without a satisfactory knowledge of the aetiology of disease, however, his explanation for this situation was based on a series of proto-evolutionary and environmental assumptions. That troops lived longer in New Zealand than elsewhere, he argued, demonstrated that the New Zealand climate and environment were more conducive to good health. Thomson's reports on New Zealand climatic conditions were also tabled in Parliament in Auckland, and published in the Wellington provincial government gazette. His papers gave scientific credibility to an already prevalent belief that New Zealand was one of the healthiest places on earth.
Thomson's research was most significant when he turned his attention to the Maori. He travelled from Auckland to the Rotorua and Taupo districts, as far south as the Mokau River, observing and recording Maori health and customs. He compiled statistics of the incidence of disease among the Maori population, and made the first anthropometric measurements of the Maori. A three-part article, 'On the peculiarities in figure, the disfigurations, and the customs of the New Zealanders', published in the British and Foreign Medico-Chirurgical Review in 1854–55, discussed the incidence of scrofula (which Thomson attributed to 'promiscuous' sexual habits); rheumatic conditions; and ngerengere, thought to be a form of leprosy, although the aetiology is still uncertain.
The statistical method which Thomson employed had flourished among the British statistical societies from the 1830s. The counting and comparing of morbidity and mortality, of poverty and human physiology, inspired confidence that the previously unknowable would be revealed by thorough, systematic, quantitative investigation. Soon after Thomson's death, medical research would become focused on the microscopic, with the investigative frontiers firmly contained within the operating theatre and laboratory. Thomson's world was uncontaminated by germs. There was room for the grand scheme, for an attempt to resolve the macro-equation of environment, climate, diet and culture. Once the statistics had revealed their patterns, the relationships were, to Thomson, obvious. Through comparative study of Maori and European conditions, the rise of civilisation could be reduced to a table, clearly demonstrating the falling away of the indicators of barbarism, as warfare, infanticide and Maori communalism gave way to the habits Europeans such as Thomson identified as 'civilised'.
Many of the assumptions about social change which would accompany the nineteenth century debate on evolution were already fully formed in Thomson's major work, The story of New Zealand: past and present – savage and civilized, which was published in two volumes in 1859, the same year as Charles Darwin's On the origin of species. There was nothing prescient in this; Darwin and Alfred Wallace's evolutionary theory provided the mechanism that was missing from writings such as Thomson's. Thomson had observed a striking contrast between the Maori and European situations: whereas Europeans were thriving in New Zealand compared with elsewhere in the world, the Maori appeared to be faced with possible extinction. Thomson attempted to explain this situation in environmental or racial terms, but was unable to give a prognosis for Maori survival. A growing awareness of the importance of social conditions and processes consequently led him to an increasing interest in history. By the mid 1850s he was working on bringing all his earlier material together in a larger scheme.
The story of New Zealand, the country's first major written history, appears to have been largely completed when Thomson left for England in 1858. The book was based on the already voluminous literature on the colony, archival material, and discussions with many of the actors involved. For Maori material, Thomson called on the assistance of the colonial secretary, Andrew Sinclair; the commissioner of Crown lands, Walter Mantell; and chief land purchase commissioner, Donald McLean.
Like most Europeans of his time, Thomson dismissed pre-contact Maori society as almost bestial. An adequate food supply quickly provided for most wants; chiefs were served by slaves and lives were divided between eating, sleeping and indolence. In Thomson's vision, capitalism, not Christianity, was transforming the Maori world. The desire for European goods, which saw competition among chiefs for fine coats, schooners, mills, horses and cattle, was portrayed as the sole mechanism of social change. Thomson interpreted the increasing rejection of Christianity evident in the 1850s not as a turning away from European culture but as the secular world of trade replacing that of theology.
His rejection of the old culture, however, was not absolute. Thomson never adequately resolved the tension between his anthropological dismissal of traditional Maori society, and his deep admiration for Maori military prowess and for Renaissance men such as Hone Heke and Te Rauparaha. The warrior chief as tactician and entrepreneur was ennobled by his poetic vision; Thomson quotes liberally and appreciatively from translated waiata.
Thomson believed his history benefited the Maori. He saw himself castigating European administrators and politicians for their failure to recognise Maori rights and for the settler determination to push Maori interests aside. However, he did not question the logic of continued and increasing settlement. A benevolent colonial regime could still assist the Maori towards equality and advancement. Thus Governor Robert FitzRoy was attacked for his failure to deal decisively with Maori intransigence despite an acknowledgement that right was often on the Maori side. Governor George Grey was criticised for his resistance to self-government, but praised for overwhelming Heke and Kawiti and undermining Te Rauparaha. These somewhat grand themes of the 1840s gave way to the petty politics of the 1850s. Although applauding the principle of self-government, Thomson found its practice venal and unflattering to democracy. He had little good to say of administrations formed by the politicians during this decade.
Thomson's confident prediction of steady, almost effortless amalgamation of Maori and European society would soon be shattered by the outbreak of a further series of wars in the 1860s. However, his mistaken optimism was shared by many European observers. In the 1850s New Zealand was still a mixed society, with Maori and European populations evenly balanced. Change was still being forced by both cultures, as, for example, Maori adopted new crops, adapted old methods of trade, and incorporated new symbols of status. A new generation of often missionary-educated Maori leaders was seen to have successfully adjusted to the challenge of European contact: Thomson made a feature of Wiremu Kingi Te Rangitake's agricultural success in the years immediately after the return of Te Ati Awa exiles to Waitara in 1848.
Occasionally Thomson recognised that the settler demand for land augured poorly for the immediate future. However, in juxtaposing the barbarism of the pre-European world with the civilisation of the 1850s, he ignored the extent to which the economic and cultural interests of the two peoples were, in reality, opposed. Like most Europeans who rejected tribalism, his need to generalise Maori experience blinded him to the limited nature of the agricultural boom of the 1840s and 1850s. Thomson was unable to predict that further settlement would lead to an inevitable conflict with those still powerful tribes who saw each new pressure to sell land as weakening their mana.
Despite this failing, however, Thomson's enthusiasm for statistical and environmental medicine, and his keen observation of politics and race relations, were the basis of a history which has been a model for many of those which have followed. His scientific papers, meanwhile, remain the most important medical publications on New Zealand in the early colonial period.
Although he does not appear to have married, while living in Auckland Thomson had three children with Ngahiraka Wood of Te Whakatohea. In October 1858 he was promoted to surgeon major, and the following month returned, reluctantly, to England with his regiment. In November 1859 he was transferred to active service and placed in charge of the Mauritius, a hospital steamship which provided medical support for British forces in China. Thomson was with the army when Peking (Beijing) fell and was placed in command of the force wintering at Tientsin (Tianjin). Unwell for some time, he died there probably on 4 November 1860.