How earliest man came out of many parts of Africa
FOR years, experts believed humans evolved in a single ‘Garden of Eden’ spot in Africa before spreading around the world.
But now scientists say fossil records show there cannot have been just one area.
Instead, groups of early human species were dispersed across Africa in pockets.
These communities – separated for millennia – developed diverse features in the shapes of their skulls and other bones. Over thousands of years the groups sporadically interbred to create homo sapiens.
Scientists say our species could not have developed from just one place because evidence from skull shapes does not support this theory. If it was correct, skulls would have changed shape in a smooth ‘linear progression’ over time.
But the timeline is mixed – with more recent skulls having primitive features while more ancient skulls have modern features.
For example, older skulls dating back 300,000 years at Jebel Irhoud in Morocco have small faces like us. However, their braincase is elongated, instead of spherical like a modern skull.
Earlier human fossils dating back 160,000 years ago from Ethiopia had big ‘ robust’ faces quite unlike us, but with rounder braincases. Professor Chris Stringer of the Natural History Museum and Dr Eleanor Scerri of Oxford University and colleagues put forward their case in the journal Trends in Ecology and Evolution.
The authors said early humans were kept apart by diverse habitats and shifting environmental
‘Our origin was a complex process’
boundaries such as forests and deserts. Many of the inhospitable regions in Africa today, such as the Sahara, were once wet and green, with networks of lakes and rivers, and abundant wildlife.
Similarly, some tropical regions that are humid and green today were once arid. The shifting nature of the habitable zones meant groups of humans would have gone through many cycles of isolation. This led to the development of unique primitive technologies such as stone tools, and highly diverse genes.
Professor Stringer pioneered the Garden of Eden theory but now accepts this is wrong. He said: ‘We do see a continental-wide trend towards the modern human form, but some archaic features are present until remarkably recently.
‘I have increasingly come to the realisation that our African origin was a complex process.
‘The great diversity of African fossils between 200,000 and 400,000 years ago suggests that multiple lineages existed on the African continent at that time.’ Lead author Dr Scerri said the stone tools discovered across Africa also don’t show a clear progression from crude to sophisticated.
She said: ‘ The evolution of human populations in Africa was multi-regional. Our ancestry was multi-ethnic. And the evolution of our material culture was, well, multi-cultural.’
Professor Mark Thomas of UCL added that the genetic patterns found in modern Africans also support their case.
He said: ‘ It is difficult to reconcile the genetic patterns we see in living Africans, and in the DNA extracted from the bones of Africans who lived over the last 10,000 years, with there being one ancestral human population.’