Latest news with #Scerri
USA Today
28-02-2025
- Science
- USA Today
African rainforests were home to humans much earlier than thought: 150,000 years ago
African rainforests were home to humans much earlier than thought: 150,000 years ago Show Caption Hide Caption Massive stegosaurus fossil that sold for $44.6M goes on public display Apex, a stegosaurus fossil, was lent to the American Museum of Natural History for public display after selling for over $40 million. Scientists have long believed that hundreds of thousands of years ago, humans first learned to thrive in East African grasslands before spreading out and adapting to new environments. But a new study published this week found some of our ancestors managed to survive in a tropical rainforest in West Africa much earlier than was previously known. A team of researchers found evidence that humans were living at a site in southern Côte d'Ivoire, a region of present-day rainforest, about 150,000 years ago in an environment generally believed to be a barrier to human occupation, according to the study published Wednesday in Nature. "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," study author and archaeologist Eslem Ben Arous, of Spain's National Centre for Human Evolution Research, said in a statement. "This pushes back the oldest known evidence of humans in rainforests by more than double the previously known estimate." Though its widely believed that humans first originated about 300,000 years ago from one part of Africa, we understand very little about the continent's history, according to Eleanor Scerri, leader of the Human Palaeosystems research group at the Max Planck Institute of Geoanthropology and a co-author of the new study. As the evidence of early humans living in Asian rainforests emerged, she began investigating the possibility the same phenomenon had occurred in West Africa. A challenging route to finding evidence Finding evidence of this theory presented a challenge, Scerri said, because the preservation of ancient botanical materials is notoriously poor in rainforests, and Africa's rainforests see so little rainfall it's possible they may not have been considered rainforests thousands of years ago. As she began her research, Scerri came across a decades-old book written in Russian about a deeply buried site next to a river in Côte d'Ivoire. More recent climate research suggested the area may have been "a rainforest refuge in the past as well," Scerri said previously. But when the site was first uncovered in 1982 by a joint Ivorian–Soviet expedition led by archaeologist professor Yodé Guédé of the Université Félix Houphouët-Boigny, the team didn't have the tools to determine the age of the stone tools they found or what the environment was like when people lived there. The research was strong, but Scerri said "because it was published in Russian and because it was West Africa, no one was interested, and no one knew about it." So Scerri and her colleagues tracked down Guédé who, now in his 80s, guided them back to the vast trench. The timing couldn't have been better: The team managed to cut back the vegetation and collect samples in March 2020 before they had to leave the country because of the COVID-19 pandemic and they were able to return briefly before the site was ultimately destroyed by quarrying. "One of the most rewarding things was just to see the happiness on Professor Guédé's face that this project that goes back to the 1980s, he was finally able to close that chapter," she said. New techniques lead to exciting discoveries Over the next few years, Ben Arous developed new techniques to date quartz grains from the oldest layer of sediment in which tools were found while a separate lab verified the results with another technique called luminescent dating. "It's around 150, 160,000 years old, which was exciting because it's like one of only two sites in West Africa that are that old," Scerri said. Next, the team examined the isotopes from the waxy coating of leaves, which Scerri said are "surprisingly indestructible," solidified plant remains and ancient pollen. The evidence indicated the site wasn't just small forested area, but a heavily wooded one home to key rainforest trees like oil palms and hunteria. Scerri said the team is still working to examine sediment samples and stone tools taken from a site near the trench and more exploration of West Africa needs to be done to understand these artifacts. She said the findings challenge the longstanding narrative that we "had to learn how to overcome different ecosystems as we sort of grew up as humans." "It reinforces the idea that humans have multiple roots across Africa, and that from our inception almost we were a species that could and did survive in very, very different ecosystems," Scerri said. "And the same skills that allowed us to do that, are the same skills that have put us on the moon and have us looking forward to going to Mars. It's human adaptability and our ingeniousness, coming up with ways in which you can adapt to radically different environments, is unknown in any other animal."
New York Times
26-02-2025
- Science
- New York Times
Early Humans Thrived in Rainforests
For generations, scientists looked to the East African savanna as the birthplace of our species. But recently some researchers have put forward a different history: Homo sapiens evolved across the entire continent over the past several hundred thousand years. If this Africa-wide theory were true, then early humans must have figured out how to live in many environments beyond grasslands. A study published Wednesday shows that as early as 150,000 years ago, some of them lived deep in a West African rainforest. 'What we're seeing is that, from a very early stage, ecological diversification is at the heart of our species,' said Eleanor Scerri, an evolutionary archaeologist at the Max Planck Institute of Geoanthropology in Jena, Germany, and an author of the study. In the 20th century, after scientists found many fossils and stone tools in East African savannas, many researchers concluded that our species was especially adapted to life in grasslands and open woodlands, where humans could hunt great herds of mammals. Only much later, the theory went, did our species become versatile enough to survive in tougher environments. Tropical rainforests appeared to be the toughest of them all. It can be hard to find enough food in jungles, and they offer lots of places for predators to lurk. 'You can't see what to hunt,' Dr. Scerri said, 'and you can't see what's coming for you.' But in 2018, Dr. Scerri and her colleagues challenged the idea that East African grasslands were the single cradle of humanity. The abundance of stone tools and fossils found there, they argued, might have meant simply that the region had the right conditions for preserving those traces of history. The scientists pointed to other fossils and stone tools discovered from southern and northern Africa. Those artifacts had often been dismissed as the products of extinct human relatives, rather than our own species. Dr. Scerri and her colleagues suggested that for hundreds of thousands of years, our forerunners lived in isolated populations across Africa, periodically mixing their DNA when they came into contact. If that were true, then early humans should have also been present in West and Central Africa, where rainforests were common. The oldest firm evidence of humans in African rainforests dated back just 18,000 years. But the acidic soils in tropical forests could have destroyed the bones before they turned to fossils, and tools could have been washed away. Dr. Scerri came across an older report about a site in the Ivory Coast. The researchers dug a massive trench in a hillside called Anyama. In the hard, sandy sediment, they discovered bits of plant matter as well as some stone tools, though they could not determine their age. In March 2020, Dr. Scerri and her colleagues traveled to Anyama and excavated a fresh face of sediment, where they found more stone tools. But they worked for only a few days before the Covid pandemic forced them home. They returned to the site in November 2021, only to discover that it had been illegally quarried for road building. 'It was absolutely heartbreaking,' said Eslem Ben Arous, a member of the team now at the National Center for Research on Human Evolution in Burgos, Spain. Dr. Ben Arous and her colleagues discovered a small area not far from the original dig where they found more tools. But the new site has been destroyed as well. Still, the researchers managed to gather a lot of clues. Dr. Ben Arous, an expert on geochronology, used new methods to estimate the age of the sediment layers. The oldest layer in which the researchers found stone tools formed 150,000 years ago. The sediment also preserved wax from the surface of ancient leaves. Analyzing the chemistry of the leaf wax revealed that Anyama was a dense rainforest throughout its history. Even in the ice age, when the cool, dry climate shrank jungles across Africa, Anyama remained a tropical refuge. Cecilia Padilla-Iglesias, an anthropologist at the University of Cambridge who was not involved in the new study, said that the work offered clear proof that people were living in those jungles — and that they were living there very early in the history of our species. 'It's important because it confirms what other research predicted,' Dr. Padilla-Iglesias said. Khady Niang, an archaeologist at Cheikh Anta Diop University in Senegal and an author of the study, noted that many of the oldest artifacts discovered were massive chopping tools crafted from quartz. She speculated that the Anyama people used them to dig up food or hack their way through the rainforest. 'If you move a lot, you need tools to cut the tress that hinder your path,' Dr. Niang said. The distinctive tool kit makes Dr. Scerri suspect that the Anyama people had already lived in the rainforest long before 150,000 years ago. 'They're not people who have just arrived,' she said. 'These are people who had the time to adjust to their living conditions.'
