Primitive Humans Resided in African Rainforests Much Before the Known Period, Researchers Find Tools to Confirm

The evolution of humans and their journey across the earth have always been a subject of interest for experts. It is well-known that modern humans originated from Africa. Yet many aspects regarding their eventual world domination and even settlement in the region are unclear. A recent study published in Nature sheds light on one of the biomes in Africa that modern humans populated during their burgeoning in Africa. 

The biome that is the focus of the study is rainforests. Before this study, researchers believed that human habitation in rainforests was a relatively recent phenomenon, stated Science Daily. A huge reason behind this was that experts thought the typical features of rainforests were not supportive of activities conducted by primitive humans. However, evidence collected from Côte d'Ivoire in West Africa provides a different story. Tools collected from the site showcased that humans were living in the rainforests of the region for around 150 thousand years.

The site was first explored in the 1980s by a team including Professor Yodé Guédé of l'Université Félix Houphouët-Boigny, a co-author in the study. The investigation unveiled a deeply stratified area containing several stone tools. At that time, the technology was not advanced enough to figure out the age of these stone tools or the past ecology of the associated site.

Many years later, some climate models of the site were created, which indicated that it was possibly a rainforest in the past. This intrigued researchers because evidence of human settlement in the area could give them the oldest known evidence of human habitation in rainforests. "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 decided to explore the site again. "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, a researcher at the University of Liverpool, and the Max Planck Institute of Geoanthropology. The researchers were glad that the team started the investigation when they did because, just after their revisit, the site was destroyed due to mining activities. 

Researchers analyzed pollen, phytoliths, and leaf wax isotopes found at the site, which showcased that the features of this region were typical of what was found in humid West African rainforests. This backed the claim made by the climate models that the region was indeed a rainforest. 

The stone tools were examined using techniques like Optically Stimulated Luminescence and Electron-Spin Resonance. The outcome indicated that they were around 150,000 years old. This result was huge as this completely changed the relationship between modern humans and rainforests in terms of habitation.

"Before our study, the oldest secure evidence for habitation in African rainforests was around 18 thousand years ago and the oldest evidence of rainforest habitation anywhere came from Southeast Asia at about 70 thousand years ago," explains Dr. Eslem Ben Arous, a researcher at the National Centre for Human Evolution Research (CENIEH), the Max Planck Institute of Geoanthropology and lead author of the study. "This pushes back the oldest known evidence of humans in rainforests by more than double the previously known estimate." Researchers are hopeful that after these findings more similar sites will be investigated.