 The staples thesis states that export of raw materials can sustain economic growth, while its critics argue that reliance on commodity export should not delay the development of basic manufacturing and provision of services.Among his strongest critics was Robin Neill who advocated a post-Innisian thesis, explaining the economic development of Canada as an expression of variegated regions (population density, cultural politics, geographic characteristics) and of their particular north-south relationships with the United States.Historians continue to use elements of the Innis Core-periphery model, applying it for example to British Columbia.