Humans lived in rainforests 80,000 years earlier than we thought

For a long time, scientists believed that early humans avoided rainforests, considering them difficult places to inhabit.

Dense vegetation, limited open spaces, and a challenging food supply led researchers to assume that humans only ventured into these environments much later in history.

However, new findings challenge this idea, showing that humans were living in African rainforests at least 150,000 years ago.

A fresh perspective on human evolution

Our species, Homo sapiens, originated in Africa around 300,000 years ago.

While much research has focused on understanding how early humans adapted to different environments, rainforests have often been overlooked. They were generally seen as barriers to human movement and settlement.

The new study reveals that early humans not only survived in rainforests but made them home much earlier than previously thought. The researchers discovered evidence of human presence in the rainforests of present-day Côte d’Ivoire dating back 150,000 years.

This finding reshapes our understanding of human evolution, suggesting that our ancestors lived in a range of environments – not just open grasslands and savannas.

Rediscovering an old site

The story of this discovery dates back to the 1980s when Professor Yodé Guédé of l’Université Félix Houphouët-Boigny first investigated the site as part of a joint Ivorian-Soviet mission.

During the initial excavation, researchers found stone tools buried deep in the soil, indicating human presence.

However, at the time, they could not determine the exact age of the tools or the environmental conditions of the site when humans lived there.

More recently, the Human Palaeosystems Research Group set out to re-examine the site using modern dating and analysis methods. This work was urgent because mining activity was rapidly destroying the site.

“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, 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.”

Advanced dating techniques

Guided by Professor Guédé, the researchers returned to the original excavation site. They used modern dating techniques to reassess the age of the tools.

“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.

Using dating techniques like Optically Stimulated Luminescence and Electron-Spin Resonance, the team confirmed that the artifacts were buried roughly 150,000 years ago.

Before this study, the oldest confirmed evidence of human presence in African rainforests dated back only 18,000 years, while the earliest known rainforest habitation anywhere was from Southeast Asia around 70,000 years ago.

“This pushes back the oldest known evidence of humans in rainforests by more than double the previously known estimate,” explained study lead author Dr. Eslem Ben Arous, a researcher at the National Centre for Human Evolution Research (CENIEH).

Early humans in a dense rainforest

To understand the environment these early humans lived in, the researchers examined sediment samples including pollen, plant remains called phytoliths, and leaf wax isotopes.

The analysis showed that the region was heavily wooded at the time, with pollen and leaf waxes characteristic of humid West African rainforests.

Additionally, low levels of grass pollen indicated that this was not just a narrow strip of forest – it was a dense rainforest.

“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.

A new understanding of early humans

The discovery adds a new dimension to the story of human evolution. Instead of living exclusively in open landscapes, early humans were far more adaptable than previously thought.

“Convergent evidence shows beyond doubt that ecological diversity sits at the heart of our species,” said Professor Scerri. “This 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?”

The research opens up new possibilities for understanding how early humans shaped and adapted to different environments.

As scientists explore more sites across West Africa, further surprising discoveries about the locations and lifestyles of our ancestors may soon emerge.

The full study was published in the journal Nature.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–