He taught in universities in Malawi, Zambia and the United States and his research in the first two countries inclined him toward the view that Central Africa underwent a period of underdevelopment that began in the mid-19th century and accelerated under colonial rule.
After his return to the United States, he cooperated with Landeg White on studies of colonial Mozambique and on the value of African poetry and songs as a source of oral history.
His father, Hazen Claude Vail, from Belleisle, New Brunswick, moved to Boston as an adult and his mother, born Mary Teresa MacLean in Cape Breton Island, arrived there as a young girl.
His theme, developed in four significant papers published between 1975 and 1981, was that the in Indian Ocean ivory and slave trades created a demand for imported goods among the people to the west of Lake Malawi in the late 18th and early 19th century and prompted social differentiation within their traditional societies.
[11] Although Mbelwa's Ngoni retained their autonomy until 1904, Vail considers that their social and economic position and those of the Tumbuka were weakened as previous relatively egalitarian class systems became more unequal when they were drawn into the capitalist economy.
[13] Restrictions on Africans possessing guns for hunting elephants and other wild animals deprived them, in Vail's view, of sources of income and meat, and the imposition of a hut tax and land expropriation in Northern Rhodesia in the first decade of the 20th century further impoverished this area.
[14] According to Vail, the Ngoni invasions and the advent of colonial rule had created the so-called Dead North in Nyasaland and impoverishment around Chipata in North-Eastern Rhodesia.
The colonial policies in these areas and in Mozambique resulted in leaving local African men at best little choice but become labor migrants[15] and at worst in their forced recruitment for the mines, farms and other employers of Southern Rhodesia and South Africa.
He argued the country's economy was burdened by heavy debts arising from colonial railway construction, which he considered was designed to benefit British companies and interests at the expense of Nyasaland and which hindered its economic development.
[28] This revival reflected the artificial origin of most post-colonial African states and their rapid adoption of one-party rule: the development of regionalism and tribalism was a reaction to the dominant party trying to impose a false unity on the existence of ethnic diversity.
[29] Vail did not accept, as other authors had claimed, that ethnicity resulted from the colonial powers’ divide-and-rule tactics, from the rigid classification of African peoples into fixed tribes by European anthropologists or when previously isolated rural groups came together and into conflict in urban or industrial settings.
[31] Although accepting that all these explanations might have some validity, Vail considered them unhistorical and pointed to the impoverishment of Central and Southern Africa in the late 19th and early 20th century through ecological catastrophes such as the rinderpest epidemic, disease, locusts and famine, colonial land expropriation and taxes and labor migrancy, all of which amounted to African people losing control of their lives.
[33] In the decade following independence in 1964, political views in Malawi were frequently expressed in ethnic terms, and groups that had prospered under the colonial regime were stigmatized as being unfaithful to the country's Chewa culture which the ruling party and president promoted.
In contrast, the Yao in the south, including many Muslims debarred from Christian education, and the Chewa in the centre, where fewer missions were founded, were more resentful of the intervention of the colonial state and protective of their traditional culture than motivated by political aspirations.
[38] Many of the leading figures in the Nyasaland African Congress in the late 1950s and early 1960s were Tumbuka speaking northerners or graduates of Blantyre Mission and, in 1963, in preparation for independence, these took a majority of the ministerial posts in Banda's government.
Shortly after independence, in the 1964 Cabinet Crisis, the rejection of their demand for more rapid Africanisation, a key aim of the mission-educated elite, led to their resignation or sacking and, in most cases, their exile.
[41] Towards the end of his career, Vail widened his interests, including a return to studying Bantu linguistics[2] and at the time of his death, he had four books in progress, three on Central Africa Spirits, Women, and Deprivation, in Malawi and Zambia since 1850, a dictionary of Lakeside Tonga, and Ideophones as stylistic devices in Tumbuka,[1][2] the fourth was on ethnogenesis in modern Togo.
Two more recent assessments are that British rule was a mixed blessing for many of the peoples of Northern Rhodesia and Nyasaland, as it brought an end to warfare and slave raiding, yet redirected much of their productive labor toward the capitalism of the south,[43] and that many labor migrants travelled south clandestinely, ignoring governmental restrictions, in search of financial security; although many were exploited, others achieved modest prosperity after their return from their savings out of higher wages earned abroad.
However, many workers left independently, disregarding government restrictions and licensed recruiters[56] For much of the first half of the 20th century, there was a debate on whether Nyasaland should have as its main economic function agriculture on European owned estates, peasant cash-crop production or the supply of migrant labor.
The Nyasaland government only had to pay interest and repay capital on the loans for constructing the Trans-Zambezia Railway or Zambezi Bridge if its revenues exceeded target figures.
[62] Rather than draining Nyasaland's admittedly meagre public funds, as Vail suggests, the railway and Zambezi Bridge cost it relatively little and provided a more effective, if underutilized, link to the outside world than the previously used option of river transport.