"The fact that the test found that I am related to these wise people who paint rocks made me feel very privileged and blessed," Tutu told Business Day.
Tutu and four Namibian Bushmen have just joined the human genome club, which counts among its handful of members geneticists James Watson and Craig Venter, and three unidentified men from China, Korea and Nigeria. Until now, no one had examined the detailed genetic structure of people from southern Africa, said study co- author Vanessa Hayes, from the Children's Cancer Institute Australia and the University of New South Wales.
The research, published yesterday in the UK-based journal Nature, has provided fresh insights into human diversity and is expected to open up new avenues for medical research as scientists hunt for ways to develop drugs and diagnostic tests tailored to an individual's genetic make-up. Adding southern African genomes to the database means characteristics unique to this region can be included in future medical research.
"At the core we are all a single species and we are not that different. But it's those small differences that can make a huge difference in understanding disease, controlling it, and curing it," said Hayes
Hayes and her colleagues extracted DNA from blood samples donated by Tutu and four Bushmen, !Gubi, G/aq'o, D#kgao, and !Ai, each the eldest member of a distinct community with its own language. They sequenced the full genome for Tutu and one of the Bushmen, and the protein- coding regions from the three other men. They found 1,3-million new genetic variants.
Tutu was invited to participate in the study not only because he is a public figure, but also because he is descended from Bantu pastoralists.
Comparing his DNA with those of the Bushmen, who are hunter-gatherers and represent the oldest known lineage of modern humans, might help scientists figure out how our ancestors made the shift from hunter-gatherers to farmers 8000-10000 years ago, said Hayes. It is unclear whether hunter-gatherers were gradually displaced by farmers or whether they adapted to a new lifestyle.
"There are no hunter-gathers left in Europe. The only place left to study it is here," she said.
Researchers were surprised to find there was greater genetic variation between the four Bushmen than there is between a typical Asian and European, suggesting their communities were more distinct than had previously been thought to be the case, she said.
Prof Michael Pepper from Pretoria University said that sequencing a human genome required advanced technology that was not currently available in SA.
"It's very important that this sort of capacity be developed here," he said.
"It will reduce the risk that people from the region do not benefit from the research and ensure that effort is put into the diseases affecting this part of the world."