Columbia’s John McArthur says that Dambisa Moyo has claimed that “in the 1970s 10 percent of the population [in Africa] was living in dire poverty. That number is now over 70 percent.” She’s been quoted by Bloomberg as saying that Africa’s “poverty rate doubled between 1981 and 2002.” Niall Ferguson’s foreword to her book says “between 1970 and 1998, when aid flows to Africa were at their peak, the poverty rate in Africa actually rose from 11 per cent to a staggering 66 per cent.” (One review subsequently misquoted this as 1970-78.)
World Bank numbers (from Shaohua Chen and Martin Ravallion) say the African poverty rate was 50% in both 1981 and 2005 (the rate rose during the 1980s and fell in more recent years). That contrasts starkly with the Bloomberg quotation.
I’m having trouble finding any estimates of the poverty rate prior to 1981. Please leave suggestions in the comments. But if Africa’s poverty rate jumped from 10% to 50% during the 1970s, that would be a story worth a book of its own.