Concentration of research on fossil-rich hotspots and discoveries in the East African region risks obscuring a broader, more complex picture of human origins.

According to researchers, while East Africa is often celebrated as a fossil-rich hotspot, fossil evidence from other parts of Africa remains underexplored, potentially holding key information that could challenge or enhance our understanding of human evolution.

The Great Rift Valley in East Africa, for example, is famous for yielding fossils that have shaped much of what is known about early hominins. Discoveries like Australopithecus afarensis (“Lucy”) and early Homo species have solidified this region’s reputation as the “Cradle of Humankind”.

West Africa, Central Africa, and Southern Africa also hold potential fossil sites that may reveal important aspects of human evolution.

For example, fossils found in South Africa, such as Australopithecus sediba and Homo naledi, have provided alternative views on human ancestry. Yet, these areas have not received the same level of attention or resources for excavation and research as their eastern counterparts.

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A new study Spatial sampling bias influences our understanding of early hominin evolution in eastern Africa published last week in the journal Nature Ecology & Evolution, by researchers at the George Washington University shows the extent to which the concentration of sites in hotspots like the East African Rift System biases understanding of human evolution and calls on scientists to take that bias into account when interpreting early human history.

“Because the evidence of early human evolution comes from a small range of sites, it’s important to acknowledge that we don’t have a complete picture of what happened across the entire continent,” says Andrew Barr, an assistant professor of anthropology at the George Washington University and lead study author.

To assess fossil record bias, the researchers examined modern mammals in the Rift Valley, finding that only a small fraction are exclusive to the area, which represents just 1.6 per cent of these species’ geographic range.

Additionally, when comparing primate skulls from the Rift Valley to those from other African regions, they found that Rift Valley skulls accounted for less than 50 percent of the total variation in primate skulls across Africa.

The reasons for this imbalance are complex. Geological conditions, historical research focus, and funding priorities have all played roles in directing the spotlight towards East Africa. But as our understanding of human evolution evolves, it's increasingly clear that a more inclusive approach is needed—one that considers the entire continent of Africa.

By expanding research beyond the current hotspots, scientists may uncover fossils that fill gaps in the evolutionary timeline, provide new insights into migration patterns, and challenge existing theories.