5 ideas
Underdevelopment is not an original state of backwardness but a product of exploitation between two linked economies. The same capitalist system that developed Europe underdeveloped Africa, so the two conditions must be explained together rather than as separate histories.
The Atlantic slave trade removed millions of young, able-bodied people, which cut Africa's labour force and population growth for centuries. It also redirected African political energy toward warfare and captive-raiding instead of production, so societies organised around supplying captives rather than developing agriculture and industry.
European trade exchanged cheap mass-produced goods such as cloth, guns and alcohol for African captives and raw materials. Imported textiles undercut local craft production like weaving and ironworking, so African technology stagnated while Europe's industries gained markets and capital.
Railways, roads and ports under colonial rule ran from mines and plantations to the coast, built to export raw materials rather than to integrate African economies. Education and health services were minimal and trained only the clerks and labourers the colonial system needed, so the apparent gifts of colonialism served extraction.
Colonial regimes forced African economies into producing one or two export crops or minerals, using taxes and coercion to push peasants into cash-crop production and wage labour. This left economies structurally dependent on foreign markets and prices they did not control, and that dependency persisted after independence.