The Nile has apparently not changed course in 30 million years

How old is the Nile?

… It has been suggested that the Nile in its present path is ~6 million years old, whereas others argue that it may have formed much earlier in geological history. Here we present geological evidence and geodynamic model results that suggest that the Nile drainage has been stable for ~30 million years. We suggest that the Nile’s longevity in essentially the same path is sustained by the persistence of a stable topographic gradient, which in turn is controlled by deeper mantle processes. We propose that a large mantle convection cell beneath the Nile region has controlled topography over the last 30 million years, inducing uplift in the Ethiopian–Yemen Dome and subsidence in the Levant Sea and northern Egypt. We conclude that the drainage system of large rivers and their evolution over time can be sustained by a dynamic topographic gradient.

Apparently, an older Nile flowed through Libya, into the Sirte Rift (see image):

nile… we present geological and geophysical arguments supporting the idea that the Nile has been sustained by a mantle ‘conveyor belt’ operating through most of the Tertiary, with a convective upwelling centred under the Ethiopian highlands and a downwelling under the eastern Mediterranean, creating a topographic gradient that supported the Nile’s course over ~30 Myr. Such a course, which is similar to the present-day one, was likely established in the early Oligocene (30 Ma). Before that, our modelling shows that the drainage pattern was probably directed northwestward and controlled by the rifting process occurring in the Gulf of Sirte.

This indicates that at that time, rivers that drained into the Mediterranean Sea flowed farther to the west, possibly along the Sirte Rift that runs from northwest to southeast, which at that time was actively subsiding and being filled with a thick pile of sediments, indicating the activity of a large continental drainage…

Fascinating stuff. Read the whole paper here. (H/T Charles Onyango-Obbo)

As readers of the blog know, Nile waters are currently the subject of a diplomatic struggle between Ethiopia and Egypt. The US government recently offered to help negotiate a settlement. The parties involved set a January 15, 2020 deadline for negotiations. Stay tuned.

Why has economic growth reduced poverty in some African states but failed in others?

This is from an excellent paper by Rumman Khan, Oliver Morrissey and Paul Mosley:

Between 1990 and 2012, for most of the developing world, poverty has halved or more than halved except in sub-Saharan Africa (SSA). The simple poverty headcount fell from about 60% to 15% in East Asia; 50% to 25% in South Asia; 20% to 10% in Latin America; but only from 57% to under 43% in SSA (Beegle, Christiaensen, Dabalen and Gaddis, 2016: 21- 22). This is despite more than a decade of impressive growth in SSA, averaging 5-6 per cent per year since the late 1990s (Devarajan, 2013: S9). Some countries did (almost) halve poverty, such as Ghana (McKay and Osei-Assibey, 2017) and Uganda (Kakande, 2010), and many achieved significant reductions. In contrast, populous countries such as South Africa and Nigeria, on the available evidence, have not achieved significant poverty reduction.

The authors note that the effects of growth on poverty reduction across Africa has been bimodal. And this is their explanation:

povertyTo explain variation within SSA in poverty reduction, we consider aspects of colonial experience associated with the emergence of differing potential for redistributive policies to emerge after independence. Following the approach of Myint (1976) and others, we classify SSA countries into two groups according to the economic strategies used by the colonial authorities, using pre-independence data on factors such as inequality, land ownership by Europeans and political participation by Africans (the process is detailed in Appendix A, with validation by cluster analysis). In smallholder production economies, African agricultural smallholders had economic and some political participation. In contrast, extractive production economies dominated by foreign-owned mines and large-scale farms fostered the emergence of an elite politics characterised by urban bias and capital-intensive production technologies. During the colonial period African economies became clustered around a bimodal structure, which provided better opportunities to the poor in countries whose production was based on the development of labour-intensive smallholder exports than in countries whose growth strategy was based more on capital-intensive mines and large farms. We then test if the growth elasticity of poverty differs between these two groups of countries, using available (PovcalNet) poverty data since 1985, noting that mean growth rates for the two groups were very similar. The analysis shows that the smallholder group significantly outperformed the extractive group, smallholder experience is a significant predictor of poverty reduction, and inclusion of other potential explanatory variables does not alter the conclusion.

I recommend you read the whole paper (including the very rich appendix).