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
Burundi some Hutu felt this was unjust and ethnic tensions were further increased. In October 1965, an attempted coup d'état led by the Hutu-dominated police was carried out but failed. The Tutsi dominated army, then led by Tutsi officer Captain Michel Micombero purged Hutu from their ranks and carried out reprisal attacks which ultimately claimed the lives of up to 5,000 people in a precursor to the 1972 Burundian Genocide. King Mwambutsa, who had fled the country during the October coup of 1965, was deposed by a coup in July 1966 and his teenage son, Prince Ntare V, claimed the throne.