Ancient humans lived in tropical rainforests much earlier than we first thought, a new study finds.

Before now, the earliest evidence of humans (Homo sapiens) living in rainforest environments dated to 70,000 years ago in Asia and Oceania, and only 18,000 years ago in Africa.

Now, according to a new study published in the journal Nature, researchers have found evidence that humans lived in rainforest-like areas in Africa as far back as 150,000 years ago. “Our results push back the earliest known presence of humans in tropical forests by more than twice the previously established estimate in another region of the world and also in Africa,” study lead author Eslem Ben Arous, a researcher at the Max Planck Institute of Geoanthropology in Germany, told Live Science in an email.

Modern humans evolved from our hominin ancestors in Africa some 300,000 years ago, according to the oldest known H. sapiens fossils, which were found in Jebel Irhoud, Morocco. Others discovered in Ethiopia date to about 200,000 years ago. However, these were found in areas that are thought to have been grasslands at the time of ancient human inhabitance.

In the 1980s, researchers discovered stone tools, such as picks, buried deep underground at a site named Bété I in West Africa’s Ivory Coast. But at the time, they were unable to date the stone tools, according to a statement. Now, with the advent of new techniques, such as optically stimulated luminescence, which enables researchers to see when objects were last exposed to heat from the sun’s rays, researchers were able to date the tools to 150,000 years ago.

What’s more, the team uncovered traces of ancient rainforest-specific plants, offering new insights into the humid environments in which these ancient humans lived. “Our palaecological study have shown the presence of Hunteria and Oil Palms, they are typical taxa [a group of organisms] for this ecozone and that [of] a wet tropical forest,” Ben Arous explained.

Nowadays, the southern Ivory Coast is a tropical rainforest ecosystem, but until now, it was unclear whether it was still a wet tropical forest 150,000 years ago. These discoveries indicate that rainforest-like environments were not a barrier to human expansion, and instead were inhabited hundreds of thousands of years ago. Additionally, the presence of such old human artifacts in this region supports the theory that Homo sapiens may have arisen in multiple places around Africa, rather than all originating in a single location and spreading outward.