Archaeologists have uncovered a continuous record of some of the earliest human populations in Africa.The archaeological sites detail the lives of early humans who have lived continuously in the area dating back to around 300,000 years ago. The records provide evidence that early human populations underwent a genetic-bottleneck during a late Ice-Age period when much of tropical Africa became uninhabitable.
The team of archaeologists, led by Pamela Willoughby of the University of Alberta, excavated two sites, ‘Magubike’ and ‘Mlambalasi’, located in the Iringa region of southern Tanazania.
"Some of these sites have signs that people were using them starting around 300,000 years ago. In fact, they're still being used today," says Professor Willoughby, who led the team of archaeologists working on the Iringa Region Archaeological Project.
"But the idea that you have such ancient human occupation preserved in some of these places is pretty remarkable."
The fragments of a human skeleton at Mlambalsi dating back to the late Pleistocene Ice Age, suggests that humans lived at the site during a time went the early human populations are thought to have undergone a population bottleneck – a decrease in genetic diversity when humans almost became extinct. The date of the skeleton is important because it provides a new opportunity to trace the evolution of modern humans before and after they are left Africa, known as the ‘Out of Africa’ theory.
The archaelogists believe that early modern Africans were forced to adapt to the environmental changes brought on by the glacial periods by remaining in the highlands of Tanzania and developing new technologies. At both Magubike and Mlambalasi an abundance of different types of tools dating from the middle Stone Age to the Iron Age (between 280,000 and 50,000 years ago) have been found.
"It was only about 20 years ago that people recognized that modern Homo sapiens actually had an African ancestry, and everyone was focused on looking at early Homo sapiens in Europe who appeared around 40,000 years ago," says Willoughby.
"But we now know that as far as back as around 200,000 years ago, Africa was inhabited by people who were already physically exactly like us today or really close to being the same as us. All of a sudden, it's not Europe in this time period that's really important, it's Africa."
The findings are published in the journal Quaternary International.