Why doesnt education actually help Africans?

This paper made me sit up. If a country like Nigeria, which contains 1/5th of the population of the entire African continent, one of the best educated countries, with perhaps one of the best resourced landscapes shows a return for education of approximately 2-3% (the increase in personal  income for every additional year of schooling) compared to approximately 10% for the USA, then its not surprising that quite a lot of the educated middle class of Nigeria (and rest of Africa) is trying to emigrate out of Africa into the western nations.

The abstract of the paper is as follows:

In the last two decades, the social and economic benefits of formal education in Sub-Saharan Africa have been debated. Anecdotal evidence points to low returns to education in Africa. Unfortunately, there is limited econometric evidence to support these claims at the micro level. In this study, I focus on Nigeria, a country that holds 1/5 of Africa's population. I use instruments based on the exogenous timing of the implementation and withdrawal of free primary education across regions in this country to consistently estimate the returns to education in the late 1990s. The results show the average returns to education are particularly low in the 90s, in contrast to conventional wisdom for developing countries (2.8% for every extra year of schooling between 1997 and 1999). Surprisingly, I find no significant differences between OLS and IV estimates of returns to education when necessary controls are included in the wage equation. The low returns to education results shed new light on both the changes in demand for education in Nigeria and the increased emigration rates from African countries that characterized the 90s.

Are you going to blame bad governments? corruption? bad technology? health problems? Geo political issues? Or what have you? At end of the day, the policy prescription has always been to increase the spend in education. See this graph for the implementation of free education in Nigeria:

The author states that the African continent lost 60,000 professionals in just 5 years between 1985 and 1990. That is a huge migration and loss for the countries concerned, specially when you consider how difficult it would be to train a lawyer, doctor, university lecturers in countries with resource constraints. And if this happens constantly, then the continent will be going into reverse! If this is what happens when you are educated, then its obvious that the enrolment rates are going to fall and economic development will fall.