Last updated July 13, 2018 at 12:21 pm
Humans did not have a single ancestral population, researchers say.
We humans were a diverse lot, and always have been, even before we marched out of Africa 300,000 years ago.
After bringing together the relevant archaeological, fossil, genetic and environmental data, an interdisciplinary team of researchers says the “textbook narrative” of human evolution that casts Homo sapiens as evolving from a single ancestral population is just not right.
In fact, they say, early humans comprised a subdivided, shifting, pan-African meta-population with physical and cultural diversity.
“In the fossil record, we see a mosaic-like, continental-wide trend toward the modern human form, and the fact that these features appear at different places at different times tells us that these populations were not well connected,” said Eleanor Scerri, a British Academy postdoctoral fellow in archaeology at the University of Oxford and the Max Planck Institute for the Science of Human History.
“This fits with a subdivided population model in which genetic exchanges are neither random nor frequent. This allows us to start detailing the processes that shaped our evolutionary history.”
Barriers created migration opportunities
Part of the reason was the physical nature of Africa itself. A series of shifting rivers, deserts, forests and other physical barriers created migration and contact opportunities for groups that may previously have been separated, and may well have become isolated again.
“To understand our genetic and cultural diversity or where being human comes from – our behavioural flexibility and biological plasticity – we have to look at an ancient history of population subdivision and diverse ecologies across Africa,” Scerri said.
The researchers say their findings will allow models of human evolutionary history to reject the concept of a simple linear progression toward a recognisably human form in favour of a more accurate account of the complexity and irregularity involved in the evolution of our species and an acknowledgment of its pan-African origin.
“In bringing together people from such diverse fields, we’ve arrived at a place where we can begin to address some key questions about our shared ancestry and even emerge with new questions we haven’t known to ask before,” Scerri said.
“We are an evolving lineage with deep African roots, so to understand this history we must re-examine evidence from diverse sources without a priori conceptions.”
The paper published in Trends in Ecology & Evolution.