Study published online in the Oxford University Press journal

A new study has revealed that Indians, Europeans and people from West Asia share a common genetic mutation that allows them to digest milk.

The study was carried out by scientists from the Centre for Cellular and Molecular Biology (CCMB) in collaboration with researchers from nine other institutions, including Cambridge University, University of Tartu, Harvard Medical School, Genome Foundation, Hyderabad and Chettinad Academy of Research & Education, Chennai. It was published online in the Oxford University Press journal Molecular Biology and Evolution.

Genetic affinities

Deputy Director of CCMB and principal Investigator of the Indian team Kumaraswamy Thangaraj said the frequency of the mutation was found to be predominant among North Indians and was in line with the findings of a previous CCMB study which showed that North Indians shared lot of genetic affinities with Europeans.

Lactase-persistent

Only 32 per cent of people world over are lactase-persistent and have the ability to digest milk and the genetic mutation enabling that process got evolved in the last 10, 000-12,000 years when humans started domesticating animals and began drinking cattle milk. Before that humans did not have that ability and constant consumption of milk over thousands of years made the body to adapt through mutation of lactase gene.

Natural selection

“It was the process of natural selection,” Dr. Thangaraj added.

With previous studies revealing that lactase persistence evolved in the last 10,000 years independently in Europe, West Asia and Africa, the present research sought to determine its evolution in the sub-continent, given the high-levels of milk consumption in India and domestication of cattle in the Indus Valley, roughly 7,000 years ago.

He said that while the enzyme lactase to break down sugar in milk is produced in children, it's production is normally stopped in adults. The deficiency of the enzyme causes lactose intolerance in people.