Origins of Hutu, Tutsi and Twa adults has a high capacity for lactose digestion, a surprisingly high number for an agrarian people, which Mamdani suggests may be the result of centuries of intermarriage with Tutsi. Bethwell Ogot in the 1988 UNESCO "General History" further notes that the number of pastoralists in Rwanda increased sharply around the fifteenth century. Although Luis et al. (2004) in a more general study on bi-allelic markers in many African countries found a statistically significant genetic difference between Tutsi and Hutu, the overall difference were not large. Modern-day genetic studies of the Y-chromosome generally indicate that the Tutsi, like the Hutu, are
Rwandan genocide government blocked "Inyenyeri News", "The Rwandan", and "Le Prophete." In a documentary, BBC mentioned that a significant number of Hutus were killed and discussed theories of the RPF shooting down the president's plane. In response to the documentary, the Rwandan government shut down BBC in the local to BBC promoting a "revisionist" position on the genocide in a documentary. While before the genocide, Rwandan history textbooks would acknowledge and highlight differences between Tutsi and Hutu people, today, the only government approved Rwandan history textbook stresses the Rwandans as one people and virtually ignore the ethnic differences and pre-genocide conflicts. Furthermore,