Our evolutionary ancestors, the bacteria wriggling around in the primordial dust, look nothing like us today. However, based on existing data, human origin cannot be definitively traced to a single place at any single point in time.
There may never have been such a period, according to a group of scientists who undertook a detailed study of our modern knowledge of human ancestry. The earliest recorded appearances of Homo sapiens traits and behaviours, on the other hand, are consistent with a variety of evolutionary histories.
We simply don’t have a large enough fossil record to definitively rule on a specific time and place in which modern humans emerged.
“Some of our ancestors would have lived in groups or societies that can be established in the fossil record, while very little will be known about others,” said anthropologist Chris Stringer of London’s Natural History Museum.
“Growing awareness of our complex human origins could extend the geographic focus of paleoanthropological fieldwork over the next decade to regions historically considered peripheral to our human evolution, such as Central and West Africa, the Indian subcontinent, and Southeast Asia.”
We do have some broad notions about our past. About a million and 300,000 years ago, Homo sapiens split from archaic ancestors (by which time nine distinct human species populated the planet).
Then we know that between 300,000 and 60,000 years ago, modern human ancestors diverged in Africa.
Finally, between 60,000 and 40,000 years ago, modern humans migrated out of Africa and across the globe, interbreeding with Neanderthals and Denisovans until dying out.
Human Origin Research
According to the researchers, a more specific place and period in Africa for modern human diversification cannot be found based on current evidence, such as genomic data and the fossil record.
“Contrary to popular belief, neither the genetic nor the fossil record have revealed a given time and place for our human origin,” said geneticist Pontus Skoglund of the Francis Crick Institute in the United Kingdom.
“It’s possible that such a point in time did not occur when the majority of our ancestors were found in a tiny geographic area and the characteristics we associate with our species first appeared. For the time being, it would be beneficial to abandon the concept of a single time and place of origin.”
Instead, the researchers emphasise the importance of separating the evolution of Homo sapiens-related anatomy, physiology, characteristics, and behaviours from genetic ancestry. This will help distinguish the question of when human ancestry first appeared from the question of when human behaviour first appeared.
They point out that combining the two risks oversimplifying what is likely to be a long, continuous, and complex operation.
“As a result, major emerging questions concern the processes drove and maintained this human patchwork, with all its complex ancestral threads, over time and space,” said Max Planck Institute for the Science of Human History archaeologist Eleanor Scerri.
“Understanding the relationship between fragmented ecosystems and changing human niches will certainly play a key role in unravelling these issues, clarifying which demographic trends provide the best match with the genetic and palaeoanthropological record,” says the researcher.