The potato took 200–250 years, in spite of organized encouragement, to become accepted in England. It took only fifty years in Ireland. Maize and cassava have come to be accepted in parts of Africa in considerably less time…. Tea, white bread, rice and soft drinks have entered many African dietaries in even shorter time and the extent to which they have spread and their consequences to nutrition have been rather severe.

F. T. SAI, Food and Agricultural Organization regional nutrition officer for Africa, 1967

ON APRIL 16, 1913, ALBERT SCHWEITZER arrived at Lambaréné, a small village in the interior lowlands of West Africa, to establish a missionary hospital on the banks of the Ogowe River. Attended by his wife, Hélène, who had trained as a nurse, he began treating patients the very next morning. Schweitzer estimated that he saw almost two thousand patients in the first nine months, and then averaged thirty to forty a day and three operations a week for the better part of four decades. The chief complaints, at least in the beginning, were endemic diseases and infections: malaria, sleeping sickness, leprosy, elephantiasis, tropical dysentery, and scabies.

Forty-one years after Schweitzer’s arrival, and a year and a half after he received the Nobel Peace Prize for his missionary work, Schweitzer encountered his first case of appendicitis among the African natives. Appendicitis was not the only Western disease to which the natives seemed to be resistant. “On my arrival in Gabon,” he wrote, “I was astonished to encounter no cases of cancer…. I can not, of course, say positively that there was no cancer at all, but, like other frontier doctors, I can only say that if any cases existed they must have been quite rare.” In the decades that followed, he witnessed a steady increase in cancer victims. “My observations inclined me to attribute this to the fact that the natives were living more and more after the manner of the whites.”