Ancient DNA extracted from human skeletons has begun to reveal the worldwide history of malaria, including how the disease first reached the Americas. Human history is told through stories, songs and artifacts created over tens of thousands of years. But there were fewer traces of the pathogenic passengers who accompanied us on this journey. Malaria is particularly puzzling because the parasitic infection causes symptoms common to a wide range of diseases, and when it kills, it leaves no physical traces in human bones for archaeologists to find.

But in the last decade, advances in ancient DNA sampling have allowed scientists to extract pathogen DNA from human skeletons that are thousands of years old. For example, traces of pathogens that enter a person’s blood, including parasites that cause malaria, remain in bones and teeth after death. These methods have now enabled researchers to conduct research. epidemiology Two parasites that cause malaria: Plasmodium falciparum And Plasmodium vivax.

To learn how these parasites spread around the world, researchers examined the DNA of 36 people aged 5,500 and from five continents. They described their findings in a study published Wednesday (June 12) in the journal Nature. Comparison of parasite genomes PlasmodiumResearchers tracked when and how the malaria that infected these people moved from one region to another.

“From an evolutionary biology perspective, malaria is one of the most interesting pathogens due to its profound impact on the human genome,” said lead author Megan Michel, a postdoctoral researcher at Harvard University and the Max Planck Institute. The science of human history in Germany. There are versions, or variants, of genes that play a role in the formation of red blood cells in which malaria parasites multiply and may confer resistance to the disease; These variants are more common among people whose ancestors lived in areas with high rates of malaria.

“Using ancient DNA allows us to go back in time and gain insight into what the genomes of these pathogens looked like in the past and how they evolved with their hosts,” Michel told LiveScience.

Health researcher Dr. from Augsburg University, who was not involved in the research. Keren Landsman said the data could help scientists not only unravel the history of malaria, but also better combat the disease today.

“We can use these data to understand not only the pathology but also the evolutionary path of malaria and perhaps even new ways to beat it,” he told LiveScience. “After all, he is one of the greatest killers of our time.” Malaria kills more than 600,000 people worldwide each year.

One of the questions researchers studied was how malaria first entered the Americas.

For answers they turned to a man who lived nearly 500 years ago high in the Peruvian Andes at a place called Laguna de los Condores. Similarity between species P.vivax The virus that infected this person and other strains common in Europe at the time suggest that European colonists brought malaria to the New World. Historically, scientists have debated whether Europeans carried the parasites or survived their earlier journey to the continent with the first Americans.

“This is exciting because we’re telling the story of how these pathogens entered America,” Michel said. “The strains transmitted early in the colonization process survived, and we found genomic evidence of their connection to parasites circulating in the region today.”

Unexpectedly, the team also found evidence of malaria in colder climates. A 2,800-year-old skeleton found in Chohopani, a high-altitude region of the Himalayas, showed signs of infection P. falciparum – a surprising finding because Chohopani is too high, cold and dry for malaria-carrying mosquitoes to survive.

The researchers concluded that this individual likely contracted the disease in the lower region, just as modern travelers carry pathogens around the world.

“Globalization and the movement of people are huge factors affecting the spread of malaria today,” Michel said. “We’re moving at an unprecedented pace, and we’re seeing it in reports of malaria cases brought in by travelers. This is a big, big problem.”

The study looked at a limited number of genomes, so it cannot provide a full view of malaria’s history. One day, researchers will want to examine more DNA samples, especially from Europe and sub-Saharan Africa.

“I would like to see other pathogens that use the same pathways studied in this way,” Landsman said. “Understanding what else colonists brought, how other pathogens spread around the world, and how immunity is formed could inform future research on the prevention and treatment of many diseases.”