Other economies, such as those in sub-Saharan Africa or in the Middle East and North Africa, have not followed the same pattern, however. In Latin America and the Caribbean, the ratio has flatlined. Thus, the hypothesis of the Kuznets curve is not confirmed in all cases, which suggests that the relationship between pollution and per capita income is less direct than originally thought. An explanation for this is that the two forces defining the curve (structural change and technical change) depend on policies and institutions, whose operation brings progress towards the least polluting stage to a premature halt.