A new study suggests that our understanding of human evolution might be more incomplete than we realize, largely due to the fact that most early human fossils come from just a few specific areas in Africa.
These “fossil hotspots,” where geological conditions are ideal for preserving ancient remains, have provided a treasure trove of information for scientists.
However, relying on such a narrow range of fossil sites may be giving us a skewed view of our evolutionary history.
One of the most famous of these hotspots is the eastern branch of the East African Rift System, which includes well-known fossil sites like Oldupai Gorge in Tanzania.
Despite its significance, this area makes up only about 1% of Africa’s total surface.
This raises an important question: How much are we missing by focusing on such a small fraction of the continent?
In a study published in the journal Nature Ecology & Evolution, researchers from George Washington University examined how this concentration of fossil sites might be biasing our understanding of human evolution.
According to W. Andrew Barr, an assistant professor of anthropology at George Washington University and the study’s lead author, it’s crucial to recognize that our knowledge of early human evolution is based on a limited and possibly unrepresentative sample of fossils.
“If most of our evidence comes from just a few places, we need to be careful not to assume that we have a complete picture of what happened across all of Africa,” Barr explains.
“By acknowledging the gaps in the fossil record, we can adjust our interpretations to get a more accurate understanding of our history.”
To explore this bias, Barr and his colleague, Bernard Wood, a University Professor of Human Origins at George Washington University, analyzed the distribution of modern mammals living in the rift valley today.
They found that very few of these mammals are unique to the rift valley. In fact, the rift environment only represents about 1.6% of the total geographic range of modern mammal species.
The researchers also compared the skulls of modern primates from the rift valley with those from other parts of Africa.
They discovered that the skulls from the rift valley represented less than half of the total variation found among primate skulls across the continent. This finding suggests that the fossil record from the rift valley might not fully represent the diversity of ancient humans either.
While scientists have long understood that the rift valley is just one small piece of the puzzle, this study is one of the first to use modern mammals as a way to measure the extent of the bias in the fossil record.
The researchers emphasize that while modern mammals can’t tell us exactly where our human ancestors lived, they can help us better understand the environments and physical traits of ancient humans.
Barr and Wood argue that it’s essential for scientists to look beyond the traditional fossil hotspots and explore new areas in Africa, even if it involves difficult and time-consuming work. By expanding the geographic range of the fossil record, we can hope to create a more complete picture of human evolution.
“We need to be careful not to fall into the trap of thinking we have the whole story,” says Wood. “We should continue searching in less-explored areas to fill in the gaps and make our understanding of human evolution more accurate.”
