For generations, scientists have turned to the savanna in East Africa as the birthplace of our species. However, recently some researchers have proposed a different history: Homo Sapiens has evolved across the continent over the past hundreds of thousands of years.
If this whole African theory was true, then early humans must have thought about how they would live in many environments other than the grasslands. A survey released Wednesday shows that as early as 150,000 years ago, some of them lived deep in West Africa's rainforests.
“What we see is that from a very early stages ecological diversification is at the heart of our species,” said Eleanor Seri, an evolutionary archaeologist at the Max Planck Institute for Geoanthropology in Jena, Germany and author of the study.
After scientists discovered many fossils and stone tools in the savanna in East Africa in the 20th century, many researchers concluded that our species were adapted to life, especially in grasslands and open forest areas.
Just a little, the theory has become versatile enough for our species to survive in more severe environments. The rainforest looked the harshest of them. Finding enough food in the jungle can be difficult, and they provide plenty of places for predators to lurk.
“I don't know what to hunt,” Dr. Scerri said.
However, in 2018, Dr. Scerri and her colleagues challenged the idea that East African grasslands are the single cradle of humanity. He argued that the abundance of stone tools and fossils there may have simply meant that there were appropriate conditions to maintain historical traces in the area.
Scientists have pointed to other fossils and stone tools discovered in South and North Africa. These artifacts were often dismissed as products of extinct human parents, not our own species.
Dr. Scerri and her colleagues have suggested that for hundreds of thousands of years, our pioneers have lived in isolated African people, and regularly mixing DNA when they come into contact with each other.
If that is true, early humans should also exist in the West and Central Africa, where rainforests were common. The oldest solid evidence of humans in Africa's rainforests dates back just 18,000 years ago. However, the acidic soils in tropical forests may have destroyed bones before they transformed into fossils, and tools may have been washed away.
Dr. Scerri came across an old report on the Ivory Coast site. Researchers dug huge ditches on the hillside known as the Anyama. Among the hard, sandy deposits, they were unable to determine their age, but found plants problems as well as some stone tools.
In March 2020, Dr. Scerri and her colleagues traveled to Anyama, excavating fresh sediments, where they found more stone tools. But they worked for just a few days before the Covid pandemic forced them into their homes. They returned to the site in November 2021, but found it illegally quarrying due to road construction.
“It was absolutely heartbreaking,” said Eslem Ben Arous, a member of the National Research Centre for Human Evolution in Burgos, Spain.
Dr. Ben Aurus and her colleagues discovered a small area not too far from the original excavation where they found more tools. However, new sites are also being destroyed.
Still, the researchers managed to gather many clues. Geochronology expert Dr. Ben Aurus used a new method to estimate the age of sediment layers. The oldest layer that researchers have found stone tools formed 150,000 years ago.
The deposits also preserved wax from the surface of ancient leaves. Analyzing the chemistry of leaf wax revealed that the Agnama is a dense rainforest throughout its history. Even during the ice age, the Anyama remained a tropical shelter when cool, dry climates shrunk the jungle across Africa.
Cambridge University anthropologist Cecilia Padilla Iglesias was not involved in new research, but the work provided clear evidence that people live in those jungles and stated that they lived very early in the history of our species.
“It's important because we see what other studies have predicted,” Dr. Padilla Iglesias said.
Kadi Nian, an archaeologist and research author at Cech Anta Diop University in Senegal, pointed out that many of the oldest artifacts discovered are large-scale chopping tools made from quartz. She speculated that the Agnama people would use them to dig up food and hack the rainforest.
“If you move a lot, you need tools to cut the trees that block your path,” Dr. Nian said.
The distinctive toolkit suspects that Anyama people already lived in the rainforest 150,000 years ago. “They aren't people who just arrived,” she said. “These are people who had time to adapt to their living conditions.”
