Ecological flexibility rather than tools or genes explains why only one transition from Africa was successful around 50,000 years ago.
Today, all non-African people are thought to be descended from a small group that migrated to Eurasia about 50,000 years ago. However, fossil records show that many previous migration attempts occurred during this period, none of which leaves a permanent genetic heritage in modern populations.
In a recently published paper in Nature, the researchers provide the first clear explanation of why these previous transitions failed. A team led by Professor Eleanor Seri of the Max Planck Institute for Geographers in Germany and Professor Andrea Manica of the University of Cambridge, discovered that before the successful expansion into Eurasia, African people were beginning to use wider habitats in new and unprecedented ways.
“We have assembled a dataset of archaeological sites and environmental information covering the last 120,000 years in Africa, using methods developed in ecology that humans can use during this time to thrive.
Human niche expansion from 70,000 years ago
“Our results showed that the human niche began to expand significantly over the past 70,000 years ago, and that expansion was driven by humans increasing the use of diverse habitats, from forests to arid deserts.”
“This is an important outcome,” explains Professor Manica: “It appears to have happened during particularly favorable windows where rainfall in the Sakhallo-Arabian desert belt increases.
Flexibility, not tools or genes, guaranteed success
Many theories have been proposed to explain why dispersion from Africa was uniquely successful around 50,000 years ago. Some suggest that it is caused by new technologies or immunity obtained through mixing with Eurasian humanity. However, no clear technical breakthroughs have been identified, and previous mixed events do not seem to have helped the success of previous migrations.
In this study, researchers have shown that they have significantly expanded the scope of the environment in which humans can live within Africa before they can migrate. This broader ecological niche may have been developed by increasing contacts and cultural exchanges between groups, which dismantled geographical barriers and allowed people to thrive in more diverse landscapes.
“Unlike previous humans who disbanded from Africa, a group of humans migrating to Eurasia 60,000 to 50,000 years ago had a unique ecological flexibility as a result of dealing with climatically challenging habitats,” says Professor Seri. seed Beyond their African homelands. ”
See: “Major expansion of the human niche that precedes Africa's dispersion,” Emily Y. Hallett, Michela Renardi, Giacopo Nicolo Serasoni, Manuel Will, Robert Bayer, Mario Clap, Andrew W. Kandel, Andrea Manica, Eleanor ML Seruri, June 18, 2025.
doi:10.1038/s41586-025-09154-0
This research was supported by funding from the Max Planck Society, the European Research Council, and the Leverhulme Trust.
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