Humans Lived in Africa's Rainforests Much Earlier Than Thought

Evidence from modern day Nigeria indicates that humans relied on rainforest resources as early as 14,000 years ago, millennia before the dawn of farming.

A new study published in iScience details more 14 thousand years of human history at the Nigerian site of Iho Eleru, upending long held views that people were unable to live in rainforests before the advent of farming. This work shows that past hunter-gatherers were able to successfully exploit the sparse fats, carbohydrates and cryptic fauna of dense, closed-canopy forests for thousands of years.

Humans are marked by their ability to live in many diverse environments, from the polar regions to deserts and nearly everywhere in between. However, for many years it was thought that humans were unable to live in rainforests unless they practiced farming or exchanged food with farmers. This is because rainforests resources are often sparsely distributed and the animals difficult to hunt thanks to low visibility. While discoveries in southeast Asia now challenge this view, there has been no evidence showing modern humans lived in rainforests in Late Pleistocene Africa, the home of our species, until very recently.

A joint research programme headed by Dr Eleanor Scerri from the Pan-African Evolution Research group at the Max Planck Institute of Geoanthropology in Germany and Dr Emuobosa Akpo Orijemie from the University of Ibadan in Nigeria has uncovered new evidence from the site of Iho Eleru in Nigeria. Together with a suite of collaborators looking at charcoal, seeds, silicified plant fossils, pollen databases, paleoclimatic models and faunal remains, the researchers began to piece together 14 thousand years of human history at the site and showed that it consistently remained a forest 'island' in the remote past.

"Our results indicated that people inhabiting Iho Eleru had specialized knowledge of their immediate and regional surroundings, allowing them to regularly live in dense canopy forests, while hunting and gathering in both forest and savannah habitats” explains Dr Jacopo Cerasoni, who led the study as a former doctoral researcher with the Pan-African Evolution Research Group.

Charcoal studies also revealed what wood and seeds were being burned in hearths associated with the site. The trees and plants were all gathered from thick canopy forests, showing that the area formed part of a closed-canopy forest in the past.

“This was clearly rainforest in the past,” says Dr Orijemie, “and humans appear to have been comfortably present and exploiting the resources of this ecosystem.”

The team also looked at the isotopic signatures of animal teeth to determine whether they were living off grassland or forest resources. Results indicate that people at Iho Eleru relied on forest animals, with regular forays into other environments. Dr Emily Hallett, a former postdoctoral researcher in Dr Scerri's team, carried out much of the studies on the animals.

"Not only do we see humans strongly engaging with rainforest environments, but we also see they were able to leave these environments to hunt in savannahs and grasslands, because we also find these animals were being brought back to the site for consumption," says Dr Hallett.

"This work shows that humans lived in diverse environments from an early date the world over," explains Dr Eleanor Scerri. "As research from other regions in the world now shows, hunter-gatherers were able to exploit a vast range of environments well before the dawn of agriculture. It seems very likely that we will find evidence of humans in rainforests in Africa far earlier than 14 thousand years ago because there is now evidence of earlier rainforest habitation in southeast Asia. Yet we know Africa is the cradle of our species. It is exciting to see how early hunter-gatherers were able to exploit a diverse range of different environments simultaneously, rather than only being adapted to one."

"We are only just starting to explore West Africa for what light it can shed on the deep human past," adds Dr Orijemie. "We know very little about this remote period for something like 90% of Africa."