A growing body of research suggests that modern humans did not originate from a single location, but emerged through interactions between populations spread across different regions of Africa. Traditionally, scientists have explained where these populations lived based primarily on climate. New findings point to another powerful influence: disease, particularly malaria.
In a study published in scientific progressthe Max Planck Institute for Geoanthropology, the University of Cambridge, and collaborating institutions investigated whether malaria was the cause. Plasmodium falciparum It influenced where humans chose to live between 74,000 and 5,000 years ago. This period was critical because it was before humans spread widely beyond Africa and before agriculture significantly changed the way malaria was transmitted.
Diseases are formed in the places where humans can live.
The results show that malaria, one of the oldest and most persistent infectious diseases affecting humans, played a major role in shaping settlement patterns. Human populations appear to be kept away from areas with high risk of infection, effectively separating populations across the region. Over tens of thousands of years, this separation affected how populations met, interbred, and exchanged genetic material with each other, contributing to the patterns of human diversity we see today. These findings highlight that disease was not just an obstacle for early humans, but an important force shaping the course of human evolution.
Modeling the risk of ancient malaria
“We used species distribution models for three major mosquito groups along with paleoclimate models,” explains lead author Dr. Margherita Colucci from the Max Planck Institute for Geoanthropology and the University of Cambridge. “By combining these with epidemiological data, we were able to estimate the risk of malaria transmission across sub-Saharan Africa.”
The researchers then compared these malaria risk estimates to independent reconstructions of the environments that early humans could have lived in in the same region and over the same time period. Their analysis revealed that humans are consistently unable to avoid or remain in areas where malaria transmission is particularly high.
Long-term effects on human populations
“The effects of these choices have shaped human population dynamics for the past 74,000 years, and probably much longer than that,” says Professor Andrea Manica of the University of Cambridge, one of the study’s senior authors. “Malaria contributed to the population structure we see today by dividing human societies across regions. Climate and physical barriers were not the only factors shaping where human groups could live.”
Rethinking the role of disease in human history
“This study breaks new ground in the study of human evolution,” added the study’s senior author, Professor Eleanor Seri of the Max Planck Institute for Geoanthropology. “Disease was rarely thought to be a major factor shaping our species’ earliest prehistory, and without ancient DNA from these eras it was difficult to verify. Our research changes that story and provides a new framework for exploring the role of disease in humanity’s deep history.”
