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
Islam in Rwanda against the soldiers and militia of the "Interahamwe". Only once the soldiers attacked with machine gun fire were the "Interahamwe" able to enter the mosque and kill the refugees. The number of Rwandan Muslims increased after the 1994 genocide due to large numbers of conversions. Many Muslims had sheltered refugees, both Hutu and Tutsi. Some converts state that they converted to Islam because of the role that some Catholic and Protestant leaders played in the genocide. Human-rights groups have documented both incidents in which Christian clerics permitted Tutsis to seek refuge in churches, then surrendered them to Hutu death-squads, as