Tracking entwined histories of malaria, humans

New study of ancient genomes tracks disease over 5,500 years, factors in spread, including trade, warfare, colonialism, and slavery

Harvard Gazette • harvard
June 12, 2024 4 minSource

Upper Mustang region of Nepal.

Photo by Christina Warinner

Upper Mustang region of Nepal.

Photo by Christina Warinner

New study of ancient genomes tracks disease over 5,500 years, factors in spread, including trade, warfare, colonialism, and slavery

Today, Malaria represents a major public health problem across much of the globe, killing more than 600,000 people annually and infecting another 250 million. It is a disease that has been around for millions of years and is undeniably entwined with human history.

“Malaria has actually shaped the human genome,” said Megan Michel , a Ph.D. candidate in human evolutionary biology at the Harvard Kenneth C. Griffin Graduate School of Arts and Sciences . She pointed out that certain inherited blood disorders, like sickle cell disease, rose in prevalence because they provide a measure of resistance to the mosquito-borne infection.

Now a new study led by Michel reconstructs the ancient genomes of the two deadliest malaria parasites, Plasmodium falciparum and Plasmodium vivax, with an eye to understanding the pathogen’s past. The research, published this week in Nature , tracks the disease over 5,500 years, with trade, warfare, colonialism, and slavery identified as major factors in its global spread.

The findings represent a feat of collaboration and data-sharing, with 94 co-authors representing 80 institutions and 21 countries. The DNA itself was plucked from genetic sequences collected from more than 10,000 ancient humans, with Michel identifying 36 malaria-infected individuals from 26 archaeological sites on five continents.

“For a graduate student to be coordinating all of this is really, really impressive,” said co-author Christina Warinner , the John L. Loeb Associate Professor of the Social Sciences and one of Michel’s three advisers. “By reconstructing these ancient Plasmodium genomes and comparing the genetic relationships between ancient and modern parasites, we’re finally able to place malaria in its evolutionary and human history context.”

“By reconstructing these ancient Plasmodium genomes and comparing the genetic relationships between ancient and modern parasites, we’re finally able to place malaria in its evolutionary and human history context.”

Christina Warinner, the John L. Loeb Associate Professor of the Social Sciences

“By reconstructing these ancient Plasmodium genomes and comparing the genetic relationships between ancient and modern parasites, we’re finally able to place malaria in its evolutionary and human history context.”

Malaria is marked by cyclical fevers that repeat every 48 or 72 hours. Until recently, written records were the only way researchers could track the disease’s progression across time and space. “There are descriptions in Greek and Roman texts that point to the presence of malaria,” Michel said. “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 disease was also common in the U.S. until the arrival of modern drainage and insecticides in the 20th century. Warinner, a biomolecular archaeologist, pointed to the high number of U.S. presidents to suffer from malaria, including George Washington, Abraham Lincoln, and Ulysses S. Grant. “Teddy Roosevelt and JFK became infected while traveling,” she said, “but earlier presidents contracted it in their hometowns or in the Washington, D.C., area” — which was notoriously swampy.

The new paper features three compelling case studies, each illustrating the role of mobility in circulating malaria. The first concerns a Belgian cemetery , excavated between 2009 and 2011 and adjacent to the first permanent military hospital in early modern Europe. Historical records document that the Habsburg Army of Flanders recruited its soldiers from the Mediterranean region for its 80 Years’ War against Spain (1568-1648).


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