A 150,000-Year-Old Stone Tool Found In Africa Means Humans Were Living In Rainforests Thousands Of Years Earlier Than We Thought
Rainforests may have been an important center for early human evolution, challenging the idea that early humans avoided rainforests because their dense vegetation, lack of open spaces, and limited food supply made them difficult places to inhabit.
It turns out that humans were living in African rainforests at least 150,000 years ago, which is 80,000 years earlier than previously thought.
To come to this conclusion, a team of researchers reexamined an archaeological site in West Africa, where stone tools had been found.
“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,” said Eslem Ben Arous, the lead author of the study and an archaeologist from Spain’s National Center for Human Evolution Research.
“This pushes back the oldest known evidence of humans in rainforests by more than double the previously known estimate.”
Humans originated in Africa about 300,000 years ago before spreading across the globe. Research has looked into how different environments have affected human evolution, but rainforests have always been overlooked, as they were considered to be barriers to human movement and settlement.
The new study found evidence of human presence 150,000 years ago in the rainforests of the Republic of Côte d’lvoire near the southern coast of West Africa.
The site was first excavated in 1982, with excavations continuing until the early ’90s. Stone tools were uncovered and then lost in 2011 during the Second Ivorian Civil War.
The research team relocated the original trench that was dug and analyzed the sediments with technology that had not been available 30 to 40 years ago.
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Shortly after the team’s investigation, the site was destroyed by mining activity during the COVID-19 pandemic, even though it had protected status.
An analysis of quartz grains from the sediment layers revealed that the stone tools were deposited around 150,000 years ago.
The team also examined pollen, leaf wax, and other plant remains from soil samples collected at the site and determined that the region was heavily wooded at the time of early human occupation.
The samples matched the vegetation found in humid West African rainforests. The low levels of grass pollen also confirmed that the site lay within a dense woodland.
The findings raise questions about how living in rainforests influenced human evolution and how humans shaped the rainforests. Humans evolved in grasslands and had to learn how to adapt to different habitats.
It is likely the groups that were adapted to rainforests would not have encountered those used to grassland habitats very often.
“Ecosystem diversity and our adaptations to radically different ecosystems also likely moderated how people interacted and how genes were exchanged—the processes that underlie evolution,” said Eleanor Scerri, a co-author of the study.
“We now need to ask how these early human niche expansions impacted the plants and animals that shared the same space with humans.”
The study was published in the journal Nature.
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