A groundbreaking archaeological discovery in West Africa is challenging established notions of early human adaptability and migration. Evidence from a site in Côte d’Ivoire indicates that Homo sapiens inhabited dense tropical forests as far back as 150,000 years ago, pushing the earliest known occupation of such environments in Africa back by over 80,000 years. This finding suggests our ancestors were far more versatile than previously thought, mastering extreme conditions much earlier in their evolutionary journey. The research findings have been published in the journal Nature.
For decades, the prevailing theory of human evolution posited that early Homo sapiens primarily thrived in open grasslands and coastal regions, actively avoiding the harsh and resource-scarce environments of dense tropical rainforests. The thick vegetation and humid climate were considered significant barriers to human dispersal and migration across the continent. However, recent discoveries at the site of Béhové I in southern Côte d’Ivoire refute this theory, demonstrating that early humans not only survived but successfully adapted to these challenging ecosystems.
The story of this remarkable discovery traces back to the 1980s when Professor Yode Guedje of Félix Houphouët-Boigny University participated in a joint Ivorian-Soviet research mission. During excavations at the Béhové I site, located near Anyama, the team unearthed a deeply stratified deposit containing numerous stone tools. While the artifacts clearly pointed to the presence of ancient humans in what is now a rainforest, dating methods available at the time were insufficient to determine their precise age or the environmental conditions under which they were buried.
Decades later, an international research team, led by the Max Planck Institute for Geoanthropology, returned to the location. Armed with state-of-the-art methodologies, they aimed to unravel the mysteries surrounding Béhové I. The timing of their renewed investigation proved fortunate, as the site had since been degraded by local mining activities. Employing cutting-edge techniques such as optically stimulated luminescence and electron spin resonance, the scientists successfully dated the sedimentary layers containing larger stone tools, like picks, to approximately 150,000 years ago.
Dating the artifacts was only half the battle; researchers also needed to understand the environment inhabited by these early humans. To reconstruct the paleoecho of the site, the team meticulously analyzed sediment samples for microscopic plant remains. They examined pollen grains, silica-rich plant structures known as phytoliths, and leaf wax isotopes preserved within the layers.
The results were unequivocal. The analyses revealed a high concentration of tree and palm pollen, including species like Mammea africana and oil palm, characteristic of the humid West African rainforest. Conversely, the presence of grass pollen was notably low, indicating that the site’s location was within a dense forest rather than the edge of a transitional woodland. This comprehensive environmental data confirms that the humans who inhabited Béhové I were indeed living deep within a humid tropical forest ecosystem.
Prior to this study, the earliest reliable evidence of human occupation in African rainforests dated to around 18,000 years ago, while the earliest global evidence came from Southeast Asia, dated to approximately 70,000 years ago. The findings from Béhové I push back the timeline for rainforest occupation by more than double the previous estimates. This significant chronological shift underscores the remarkable ecological flexibility of Homo sapiens early in our evolutionary history.
“The body of evidence makes it clear that ecological diversity is at the core of our species,” stated lead author Professor Elenor Scerri. This adaptability likely played a crucial role in the successful dispersal of modern humans out of Africa and across the globe, enabling them to master a wide array of habitats, from arid deserts to dense jungles. The discovery at Béhové I not only reshapes our understanding of early human habitats but also opens new avenues for exploring how ancient populations interacted with and potentially shaped pristine natural environments long before the advent of agriculture.
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