Why is economic development so bad in sub-Saharan Africa?

Richard Lynn thinks it has to do with racial differences in IQ:

The Ashkenazi Jews have the highest IQ at an average of 110. This is one of the reasons that they are so successful and prominent in the professions, business and academia and as recipients of awards and prizes for outstanding intellectual work such as the Nobel Prize. For instance, in the United States Jews have been about three percent of the population during the last century and have won about a third of the Nobel prizes.

The Chinese, Japanese and other Northeast Asians have the next highest IQ at 105. This explains why Japan, South Korea, Taiwan and Singapore, have done so well economically during the last half century, and why China has achieved such high rates of economic growth in recent years since it has introduced a market economy.

The European nations have an average IQ of 100, which makes it difficult for them to compete economically against the Northeast Asians.

The lowest IQs are those of the Bushmen of the Kalahari Desert and the Pygmies of the West African rain forests at an average 53, and the Australian Aborigines at an average 62. IQs in sub-Saharan Arica are approximately 70 and this retards their economic development.

The calculation of IQs for all nations in the world has shown that IQ differences contribute significantly to differences in economic development and to our understanding of why some nations are rich while others remain poor.