A growing body of research suggests that modern humans did not originate from a single location, but instead emerged through interactions among groups spread across different regions of Africa. Traditionally, scientists have explained where these populations lived based mainly on climate. New findings now point to another powerful influence: disease, particularly malaria.
In a study published in Science Advances, researchers from the Max Planck Institute of Geoanthropology, the University of Cambridge, and collaborating institutions explored whether malaria caused by Plasmodium falciparum affected where humans chose to live between 74,000 and 5,000 years ago. This period was crucial, as it came before humans spread widely beyond Africa and before agriculture significantly changed how malaria was transmitted.
Disease Shaped Where Humans Could Live
The results indicate that malaria, one of the oldest and most persistent infectious diseases affecting humans, played a major role in shaping settlement patterns. Regions with high transmission risk appear to have pushed human populations away, effectively separating groups across the landscape. Over tens of thousands of years, this separation influenced how populations encountered one another, interbred, and exchanged genetic material, contributing to the patterns of human diversity seen today. These findings highlight that disease was not just an obstacle for early humans but a key force shaping the course of human evolution.
Modeling Ancient Malaria Risk
“We used species distribution models of three major mosquito complexes together with paleoclimate models,” explains lead author Dr. Margherita Colucci of the Max Planck Institute of Geoanthropology and the University of Cambridge. “Combining these with epidemiological data allowed us to estimate malaria transmission risk across sub-Saharan Africa.”
The team then compared these malaria risk estimates with a separate reconstruction of the environments early humans were able to inhabit across the same region and time frame. Their analysis revealed that humans consistently avoided, or could not remain in, areas where malaria transmission was especially high.
Long-Term Effects on Human Populations
“The effects of these choices shaped human demography for the last 74,000 years, and likely much earlier,” says Professor Andrea Manica of the University of Cambridge, one of the senior authors of the study. “By fragmenting human societies across the landscape, malaria contributed to the population structure we see today. Climate and physical barriers were not the only forces shaping where human populations could live.”
Rethinking the Role of Disease in Human History
“This study opens up new frontiers in research on human evolution,” adds Professor Eleanor Scerri of the Max Planck Institute of Geoanthropology, also senior author of the study. “Disease has rarely been considered a major factor shaping the earliest prehistory of our species, and without ancient DNA from these periods it has been difficult to test. Our research changes that narrative and provides a new framework for exploring the role of disease in deep human history.”
