New research shows that humans inhabited rainforests in the present-day Côte d'Ivoire (Ivory Coast) 150,000 years ago, much earlier than previously thought.
Rainforests have generally been considered natural barriers to human habitation. Before this study, the oldest evidence for habitation in African rainforests was around eighteen thousand years ago. The oldest evidence of rainforest habitation anywhere came from southeast Asia was from around seventy thousand years ago.
This study, published in the journal Nature, used new dating techniques on an archaeological site in wet tropical forest at Bété 1 (Anyama) in southern Côte d'Ivoire to reveal that human groups were living in rainforests from 150,000 years ago, showing that human evolution occurred across a variety of regions and habitats. This discovery pushes back the oldest known evidence of humans in rainforests by more than double the previously known estimate
The research was led by the Max Planck Institute of Geoanthropology and carried out by an international team of researchers, including Dr James Blinkhorn from the University of Liverpool's Department of Archaeology, Classics and Egyptology.
The origins of the study can be found in the 1980s when Professor Yodé Guédé of l'Université Félix Houphouët-Boigny first investigated the site. Results from this initial study revealed a deeply stratified site containing stone tools in an area of present-day rainforest, indicating that early humans had lived there. But the age of the tools, and the ecology of the site when they were deposited there, could not be determined.
"Several recent climate models suggested the area could have been a rainforest refuge in the past as well, even during dry periods of forest fragmentation," explained Professor Eleanor Scerri, leader of the Human Palaeosystems research group at the Max Planck Institute of Geoanthropology and senior author of the study. "We knew the site presented the best possible chance for us to find out how far back into the past rainforest habitation extended."
The team therefore mounted a mission to re-investigate the site, fortunately managing to conduct a new program of fieldwork at the site, which has since been destroyed by mining activity.
"With Professor Guédé's help, we relocated the original trench and were able to re-investigate it using state of the art methods that were not available thirty to forty years ago" said Dr. James Blinkhorn from the University of Liverpool.
The researchers used several dating techniques, including Optically Stimulated Luminescence and Electron-Spin Resonance, to arrive at a date of 150,000 years ago.
At the same time, sediment samples were separately investigated for pollen, silicified plant remains called phytoliths, and leaf wax isotopes. Analyses indicated the region was heavily wooded, with pollen and leaf waxes typical for humid West African rainforests. Low levels of grass pollen showed that the site wasn't in a narrow strip of forest, but in a dense woodland.
"This exciting discovery is the first of a long list as there are other Ivorian sites waiting to be investigated to study the human presence associated with rainforest" said Professor Guédé.
Dr Blinkhorn, who directed the fieldwork and reviewed the archaeological records from the site, adds "By incorporating previous evidence of stone tool assemblages at the site with new dating and palaeoecological studies, we were able to show not only the earliest but repeated occupations of wet tropical forests at Bété 1 (Anyama), hinting at a much wider occupation of these habitats over the past 150 thousand years"
The research was funded by the Max Planck Society and the Leakey Foundation.
DOI: 0.1038/s41586-025-08613-y
Photo captions (credit to James Blinkhorn and Max Planck Society):
