SWSCforest – by Stephen Beech
ONLINE EMBARGO 16.00 GMT, 26/02/25
Humans were living in tropical rainforests tens of thousands of years earlier than previously thought, according to new research.
The earliest evidence of humans living in such forests in Africa, around 150,000 years ago, has been discovered.
The study, published in the journal Nature, dates humans living in rainforests 80,000 years earlier than found in other sites around the world.
Humans were not believed to have lived in rainforests until relatively recently due to them being thought of as natural barriers to human habitation.
But the new study, by an international team led by the Max Planck Institute of Geoanthropology in Germany and involving University of Sheffield researchers, found that humans were living in rainforests within the present-day Côte d’Ivoire around 150,000 years ago.
The team re-excavated an archaeological site from the 1980s currently found within rainforest, in which stone tools had previously been found deep within sediments but could not be dated.
They then applied state of the art scientific methods to the site which were not available during the original study.
Ancient pollen, silicified plant remains, known as phytoliths, and leaf wax isotopes from site sediments were also analysed.
They indicated that when humans were dropping their stone tools in the region, it was a heavily wooded wet forest, typical of humid West African rainforests.
Sheffield University Professor Mark Bateman used a dating technique known as Optically Stimulated Luminescence to discover the burial age of individual grains of sand from eight samples across the site.
His work showed that the archaeological site extended back from 12,000 years ago through to around 150,000 years ago.
The results were corroborated by Electron Spin Resonance dating.
Professor Bateman, said: “The stone tools found at the site were thought to be from the Middle Stone Age, so they could have been as old as 500,000 years, or as young as 10,000 years.
“Key to finding when they were being used was the application of modern dating techniques to the sediments in which the stone tools were found.
“It is incredibly interesting to take a grain of ancient sand and be the first to know when it was deposited.
“It is even more so when the age of the sand changes what we know of how, and where, our ancient ancestors lived.”
Lead author Dr. Eslem Ben Arous, of the National Centre for Human Evolution Research (CENIEH), Spain, said: “Before our study, the oldest secure evidence for habitation in African rainforests was around 18,000 years ago, and the oldest evidence of rainforest habitation anywhere came from southeast Asia at about 70,000 years ago.
“This pushes back the oldest known evidence of humans in rainforests by more than double the previously known estimate.”
Study senior author Professor Eleanor Scerri, leader of the Max Planck Institute of Geoanthropology, said: “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.
“So we knew the site presented the best possible chance for us to find out how far back into the past rainforest habitation extended.
“This work reflects a complex history of population subdivision, in which different populations lived in different regions and habitat types.
“We now need to ask how these early human niche expansions impacted the plants and animals that shared the same niche-space with humans.
“In other words, how far back does human alteration of pristine natural habitats go?”
Prof Bateman added: “There are other sites waiting to be investigated that could provide equally as exciting results.
“However this study was completed just before the site was destroyed by mining activity, highlighting that being able to do work such as this is vitally important in being able to further study the history and evolution of the human species.”
