Research provides new cornerstone in the evolution of malaria in humans

New bioarchaeological research shows malaria has threatened human communities for more than 7,000 years, earlier than when the start of agriculture was thought to have triggered its devastating arrival.

Lead author Dr Melandri Vlok, Department of Anatomy, University of Otago, says this groundbreaking research, published today in Scientific reports, changes the whole understanding of the relationship humans have with malaria, which remains one of the world’s deadliest diseases.

“Until now, we thought that malaria had become a global threat to humans when we turned to agriculture, but our research shows that at least in Southeast Asia, this disease was a threat to humans. human groups long before that.

“This research which provides a new cornerstone in the evolution of malaria in humans is a great achievement for the whole team,” says Dr Vlok.

Still a serious health problem, as recently as 2019, the World Health Organization reported around 229 million cases of malaria worldwide, with 67% of malaria deaths in children under 5 .

While malaria is invisible in archaeological records, the disease has changed the evolutionary history of human groups, causing visible consequences in prehistoric skeletons. Certain genetic mutations can lead to inheritance of thalassemia, a devastating genetic disease which, in its mildest form, offers some protection against malaria.

Deep in mankind’s past, malaria genes have become more common in Southeast Asia and the Pacific where it remains a threat, but so far the origin of malaria has not been identified. . This research has identified thalassemia at an ancient archaeological site of hunter-gatherers in Vietnam dating back around 7,000 years, thousands of years before the transition to agriculture in the region.

In some parts of the world, cuts and fires in agricultural practices have reportedly created puddles of standing water attracting malaria-carrying mosquitoes, but in Southeast Asia, these mosquitoes are common forest dwellers exposing humans to disease long before the adoption of agriculture.

The study on the evolutionary adaptations of foragers and farmers to malaria, evidenced by 7,000 years of thalassemia in Southeast Asia, is the result of combined efforts of years of investigation by a team of researchers led by Professor Marc Oxenham (currently at Aberdeen University) and comprising researchers from University of Otago, Australian National University (ANU), James Cook University, Vietnam Institute of Archeology and Sapporo Medical University.

The research is the first of its kind to use microscopic techniques to study changes in bone tissue to identify thalassemia. In 2015, Professor Hallie Buckley of the University of Otago noticed changes in the bones of hunter-gatherers that made her suspicious that thalassemia could be the cause, but the bones were too poorly preserved to be sure. Professor Buckley called in bone microscopy expert Dr Justyna Miszkiewicz from ANU to investigate. Under the microscope, ancient samples from Vietnam showed evidence of abnormal porosity reflecting the complications of modern bone loss in thalassemia patients.

At the same time, Dr Vlok, completing his doctoral research in Vietnam, found changes in the bones excavated at a 4,000-year-old agricultural site in the same area as the 7,000-year-old hunter-gatherer site. The combined research suggests a long history of evolutionary changes in malaria in Southeast Asia that continues today.

“A lot of things came together, and then there was a surprising moment of realization that malaria was present and problematic for these people all those years ago, and long before we knew it until now.” adds Dr Vlok.