Ancient DNA Illuminates the History of Malaria, One of the World’s Deadliest Diseases

Roughly 2,800 years ago, high in the Himalayas, a man died of malaria. But the site where his remains were found, located 9,100 feet above sea level, is in a rocky, dry environment that’s too cold to support the mosquitoes that spread the disease.

“It’s the last place on Earth I would expect to find a malaria infection,” Megan Michel, an evolutionary biologist at Harvard University and the Max Planck Institute for Geoanthropology in Germany, tells the Harvard Gazette’s Christy DeSmith.

This finding was revealed as part of a new study, led by Michel and published Wednesday in the journal Nature, that illuminates the history of malaria. The parasite-caused disease is so common—it currently infects 250 million people and kills 600,000 people each year—that it became deeply intertwined with the development of the human genome.

However, diseases like malaria typically leave no physical trace in ancient remains, making them challenging to detect. Malaria is “invisible archaeologically,” study co-author Christina Warinner, an archaeogeneticist at Harvard University, tells Science’s Andrew Curry.

But with new techniques for analyzing genetic samples, the researchers managed to find very small fragments of the parasitic DNA that had become embedded into bones and teeth of malaria’s victims.

The team uncovered 36 individuals who had been infected with malaria across 26 archaeological sites on five continents. Previously, the oldest physical evidence of the disease came from a blood sample collected in Spain’s Ebro Delta in 1944. The new research pushes this date back dramatically, to 5,600 years ago in Germany—the age of the oldest skeleton in which malaria was detected.

Until now, the only source of information about malaria’s history prior to the 20th century came from written records. “There are descriptions in Greek and Roman texts that point to the presence of malaria,” Michel says to the Harvard Gazette. “But we were able to go back even further than that to show that malaria has been present in Europe for a very, very long time.”

The remains of the Nepali man were found near an ancient trade route crossing the Himalayas. The archaeological site also contains copper objects produced in the lowlands of India, where mosquitoes and malaria are common. Researchers concluded that the man was infected while traveling, then he returned home and died later.

“With this huge data set, we can zoom out and see the long evolutionary history and also zoom in and study the fate of a single individual,” study co-author Alexander Herbig, a pathogen genomicist at the Max Planck Institute for Evolutionary Anthropology in Germany, tells Science.

Tying those individual stories to the long evolutionary history of malaria led to several important findings. Samples containing the genome of Plasmodium vivax, a malaria-causing parasite, were detected across Europe throughout a long stretch of history, from the Stone Age to the 18th century, demonstrating that in the prehistoric era, malaria was not just a tropical disease.

The findings also support the idea that malaria was brought to the Americas through European colonization, rather than with Polynesian arrivals some 15,000 years ago. The oldest malaria sample from the Americas was discovered in a Peruvian skeleton of a person who lived at high altitudes in the Andes Mountains about 500 years ago. It genetically matched the P. vivax strain common in Europe at the time.

More recent American strains of malaria, though, closely resemble a version circulating in sub-Saharan Africa, Plasmodium falciparum, suggesting this parasite was transported across the Atlantic with enslaved people.

Together, the results “suggest that movement, rather than stasis, is the underlying driving force in the spread of malaria,” Nathaniel Comfort, who studies the history of medicine at Johns Hopkins University and was not affiliated with the research, tells NPR’s Melody Schreiber.

These conclusions aren’t definitive. It’s possible an older strain arrived in the Americas before Europeans did, but it went extinct and wasn’t captured in the new data, per Science. Or, since the study compared ancient samples to modern strains of malaria, the method could have missed older, genetically different versions of the parasite.

Even so, the technique used in this study holds promise for continuing to use DNA to reconstruct the histories of malaria and other pathogens. It could even lead to new treatments, Keren Landsman, a public health researcher at the University of Augsburg in Germany who was not involved in the study, tells Live Science’s Michael Schubert.

“We can use this data to understand not only the pathology but also the evolutionary route of malaria—and maybe even new ways to beat it,” Landsman tells the publication. “After all, it is one of the greatest killers of our time.”

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Rudy Molinek is Smithsonian magazine's 2024 AAAS Mass Media Fellow.