A recent study published in the journal Nature reveals that before modern humans embarked on their significant migration out of Africa around 50,000 years ago, they had already begun to thrive in a variety of ecologically diverse environments. This adaptability may have played a crucial role in their later global dispersal.
Homo sapiens, our species, originated in Africa over 300,000 years ago, with genetic data indicating that the majority of contemporary human populations outside the continent descend from a small group that began migrating approximately 50,000 years ago. Earlier research, however, suggests that some groups may have started leaving Africa as far back as 270,000 years ago, raising questions about the absence of genetic continuity from these earlier migrations.
In the new study, researchers analyzed archaeological data from sites in Africa dating between 120,000 and 14,000 years ago. Their examination of ancient plant and animal remains allowed them to reconstruct the habitats and climates that early humans encountered, providing insights into the vegetation, temperature, and rainfall of the time.
The findings indicate that around 70,000 years ago, modern humans began to diversify their habitats significantly, venturing into forests of West and Central Africa, deserts in North Africa, and regions with fluctuating temperatures.
“Humans have been successfully living in challenging habitats for at least 70,000 years,” said Emily Hallett, an archaeologist at Loyola University Chicago and co-lead author of the study.
This revelation was described as a “huge surprise” by co-senior author Eleanor Scerri, an evolutionary archaeologist at the Max Planck Institute of Geoanthropology in Germany. Scerri emphasizes that the ecological flexibility demonstrated by humans was key to their ability to spread across the globe and adapt to different environments.
Andrea Manica, another co-senior author and evolutionary ecologist at the University of Cambridge, noted that modern humans were versatile from the start, inhabiting various habitats. “What we see about 70,000 years ago is Homo sapiens becoming the ultimate generalist, pushing into more extreme environments,” he explained. This increased adaptability likely provided them with the advantage needed for their widespread migration around 50,000 years ago.
Michela Leonardi, also a co-lead author and an evolutionary biologist at the University of Cambridge, pointed out that the enhanced ecological flexibility observed was more likely the result of various factors—including larger ranges, increased intergroup contact, and a greater propensity for innovation—rather than a single evolutionary change.
These findings could provide valuable insights not only into the migration patterns of modern humans but also into broader aspects of human evolution, including the adaptations of ancient relatives like Homo erectus and the Neanderthals. William E. Banks, an archaeologist at the French National Center for Scientific Research, remarked that earlier species must also have adapted to diverse environmental conditions as they began to inhabit Eurasia.
While the precise reasons for this expansion into challenging habitats around 70,000 years ago remain unclear, Scerri suggests that changing environmental conditions may have forced such adaptations. “It was likely out of necessity,” she concluded.