Before humans spread from Africa to Eurasia and beyond, they expanded their ecological niche to include African forests and deserts, as new research shows. The authors of a new study argue that this process of adaptation to difficult habitats was crucial to the long-term successful spread of humans.

Today we know that all non-Africans are descended from a small group of people who ventured into Eurasia around 50,000 years ago. However, earlier human finds outside Africa show that there were numerous failed attempts at expansion before this time, which left no discernible genetic traces in people living today.

A new study in the journal Nature now explains for the first time why these early attempts at migration failed. A team of researchers led by Professor Eleanor Scerri from the Max Planck Institute for Geoanthropology in Jena and Professor Andrea Manica from the University of Cambridge shows that, before spreading to Eurasia 50,000 years ago, humans began to exploit different types of habitats in Africa in ways that were previously unknown. To obtain the archaeological data necessary for this analysis, researchers from the University of Tübingen evaluated information from the ROAD database of the Heidelberg Academy project "The Role of Culture in Early Expansions of Humans (ROCEEH)".

"We compiled a dataset from archaeological sites and environmental data in Africa covering the last 120,000 years. Using methods from ecology, we attempted to trace the changes in human ecological niches, i.e., the habitats that are useful and beneficial to humans," says Dr. Emily Hallet, the lead author of the study from Loyola University Chicago.

"Our findings show that humans significantly expanded their niche 70,000 years ago, driven by increased use of different habitats, such as forests and deserts," adds Dr. Michela Leonardi, one of the lead authors of the study from the Natural History Museum in London.

"This is a key finding. Previous expansions probably occurred during favorable time windows with increased rainfall in the Arabian Desert, creating 'green corridors' for humans to reach Eurasia. However, around 70,000 to 50,000 years ago, the easiest route out of Africa was more difficult than in earlier periods, and yet this expansion was considerable and ultimately successful," explains Professor Manica.

Many attempts have been made to explain the long-term, one-time successful spread of humans from Africa, ranging from key technological innovations such as the bow and arrow or brain changes to immunity to disease through interbreeding with Eurasian human forms. "The search for a single groundbreaking innovation or revolutionary change in human cognition that enabled successful emigration has so far led nowhere," adds PD Dr. Manuel Will, co-author of the study from the University of Tübingen.

However, the researchers show here that humans greatly expanded the range of habitats available to them in Africa before spreading beyond the continent. This expansion of the human niche was possibly the result of positive feedback from increased contact and cultural exchange, which enabled greater areas of distribution and the overcoming of geographical barriers.

"Unlike earlier humans who spread out from Africa, these groups, who migrated to Eurasia around 60,000 to 50,000 years ago, had a pronounced ecological flexibility that enabled them to cope with climatically difficult habitats," said Professor Scerri. "This was probably the key mechanism for the successful adaptation of our species outside its African homeland."

The research was financially supported by the Max Planck Society, the European Research Council, and the Leverhulme Trust. The ROCEEH project is funded by the Heidelberg Academy of Sciences.

According to a press release from the Max Planck Institute for Geoanthropology/University Communications at the University of Tübingen.

Publication:

Emily Y. Hallett, Michela Leonardi, Jacopo Niccolò Cerasoni, Manuel Will, Robert Beyer, Mario Krapp, Andrew W. Kandel, Andrea Manica, Eleanor M.L. Scerri: Major expansion in the human niche preceded dispersal out of Africa.

Nature, https://doi.org/10.1038/s41586-025-09154-0

Contact at the University of Tübingen:

Dr. Andrew Kandel, ROCEEH, a.kandel@uni-tuebingen.de