Persistent high intestinal lactase activity in Papua New Guinea. Lactose absorption curves in two populations

Thirty adolescent males, aged 16-19 years, all of Huli, Mendi or Dunai descent, sampled at Tari in Southern Highlands of Papua New Guinea, and 29 children aged between 9 and 15 years, all speakers of Daga and sampled at Agaun in the Milne Bay Province, have been tested for persistent high intestinal lactase activity. Three persons at Tari and five at Agaun were found to be lactose absorbers. There is reasonably convincing evidence that all five absorbers at Agaun descend from a common ancestor five generations ago, but there is no such suggestion for those tested at Tari. Gene flow from Caucasoids who penetrated both areas is possible. The presence of lactose absorbers in peoples who are not traditional users of fresh milk suggests that the culture historical hypothesis may not give a completely adequate explanation for the establishment and conservation of the lactose polymorphism in man.