Published On 4/28/2026
Climate alone was not the factor that determined the paths of early humans in Africa. Diseases may have played a subtle but crucial role in determining where they lived and how they spread.
This is revealed by a new study published on April 22 in the journal Science Advances, where researchers concluded that malaria, one of the most dangerous infectious diseases in the world, was not just a disease, but rather an environmental force that affected the distribution of humans across the African continent over a period of about 74 thousand years.
Disease determines the paths
The researchers relied on a scientific model that combines several sources of data: information about ancient climate, the spread of malaria-carrying mosquitoes, and archaeological records showing the whereabouts of early humans. By combining this data, they were able to roughly remap where the disease was spreading over time, and then compared it to locations where humans lived.
“The result was striking,” says the study’s lead author, Margherita Colucci, a postdoctoral researcher in the African Evolution Research Group at the Max Planck Institute for Geoanthropology. “The result was striking: humans did not disperse randomly, but rather tended to avoid areas with a high risk of malaria. The most livable areas were mostly those with a low risk of disease, while high-risk areas remained less attractive for human settlement.”
Colucci explains in statements to Al Jazeera Net that humans were not only searching for water and food, but were – without realizing it – also moving away from places of health danger. Pointing out that malaria did not only affect places of residence, but also played a role in separating human groups from each other.
She adds: “In some areas, the spread of the disease created what seemed like invisible barriers, which made communication between human groups more difficult. Over time, these groups lived in relative isolation, which may have contributed to the emergence of genetic diversity among peoples.”
These barriers were not fixed, but rather changed with climate change. In certain periods, the risks of disease decreased, allowing new migration corridors to be opened, while in other periods, these areas became unsuitable for settlement, so those corridors were closed.
Malaria is older than we thought
Colucci stresses that one of the most important results of the study is that malaria was widespread thousands of years before the advent of agriculture, specifically about 13 thousand years ago. This challenges the common idea that infectious diseases were primarily associated with the emergence of sedentary agricultural societies. The study indicates that disease was indeed an influential factor even in hunter-gatherer societies, which were constantly moving.
This finding also supports known genetic evidence, such as the emergence of genetic mutations that provide partial resistance to malaria – such as sickle cell anemia – early in human history, indicating that humans have been under constant pressure from this disease since time immemorial.
The study also shows that the relationship between man and his environment was more complex than thought; Human movement was not only driven by obvious factors such as climate or the availability of resources, but also by hidden factors such as the spread of diseases.
Over thousands of years, the spread of humans remained limited to areas with less health risks, before it gradually began to expand towards areas more susceptible to malaria, especially in West Africa. Researchers believe that this expansion became possible with the development of capabilities in humans that help them resist disease.
The study suggests reconsidering the way we understand human history, as it is not only a matter of conflict with nature or adaptation to the climate, but also includes confronting invisible threats, such as diseases that affected migration and settlement paths.
