Culture

West Africa “a real frontier for human evolutionary studies”

Groups of hunter-gatherers in what is today Senegal continued to use Middle Stone Age technologies associated with our species’ earliest prehistory as late as 11 thousand years ago.

Freshly found artefact from Laminia, Senegal Credit: Eleanor Scerri

This contrasts with the long-held view that humanity’s major prehistoric cultural phases occurred in a neat and universal sequence.

This is the result of fieldwork led by Dr Eleanor Scerri, head of the Pan-African Evolution Research Group at the Max Planck Institute for the Science of Human History in Germany and Dr Khady Niang of the University of Cheikh Anta Diop in Senegal. They have documented the youngest known occurrence of the Middle Stone Age.

Stone flaking methods and the resulting tools include distinctive ways of producing sharp flakes by carefully preparing nodules of rock, some of which were sometimes further shaped into tool forms known as ‘scrapers’ and ‘points.’

Lithics from Laminia (A-D) and Saxomununya (E-H). (A) unretouched flake; (B) bifacially retouched flake; (C) Levallois core evidencing a step fracture; (D) side retouched flake/scraper; (E, F) Levallois cores; (G) bifacial foliate point; (H) bifacial foliate. Credit Jacopo Cerasoni. Figure licensed under CC-BY-4.0.

Middle Stone Age finds most commonly occur in the African record between around 300 thousand and 30 thousand years ago, after which point they largely vanish.

Commenting on the findings Dr Eleanor Scerri said:

“West Africa is a real frontier for human evolutionary studies – we know almost nothing about what happened here in deep prehistory. Almost everything we know about human origins is extrapolated from discoveries in small parts of eastern and southern Africa.”

The research ranges from Senegal’s desert edges to its forests and along different stretches of its major river systems: the Senegal and the Gambia, where the team found multiple Middle Stone Age sites, all with surprisingly young dates.

“These discoveries demonstrate the importance of investigating the whole of the African continent, if we are to really get a handle on the deep human past.” says Dr Khady Niang.

“Prior to our work, the story from the rest of Africa suggested that well before 11 thousand years ago, the last traces of the Middle Stone Age – and the lifeways it reflects – were long gone.”

Explaining why this region of West Africa was home to such a late persistence of Middle Stone Age culture is not straightforward.

Dr Jimbob Blinkhorn added:

“To the north, the region meets the Sahara Desert. To the east, there are the Central African rainforests, which were often cut off from the West African rainforests during periods of drought and fragmentation. Even the river systems in West Africa form a self-contained and isolated group.”

The researchers suggest that it is possible that this region of Africa was less affected by the extremes of repeated cycles of climate change and “If this was the case, the relative isolation and habitat stability may simply have resulted in little need for radical changes in subsistence, as reflected in the successful use of these traditional toolkits,” said Dr Scerri.

“All we can be sure about is that this persistence is not simply about a lack of capacity to invest in the development of new technologies. These people were intelligent, they knew how to select good stone for their tool making and exploit the landscape they lived in,” added Dr Niang.

The results fit in with a wider, emerging view that for most of humanity’s deep prehistory, populations were relatively isolated from each other, living in subdivided groups in different regions.

Accompanying this striking finding is the fact that in West Africa, the major cultural shift to more miniaturized toolkits also occurs extremely late compared to the rest of the continent. For a relatively short time, Middle Stone Age using populations lived alongside others using the more recently developed miniaturized tool kits, referred to as the ‘Later Stone Age’.

“This matches genetic studies suggesting that African people living in the last ten thousand years lived in very subdivided populations,” says Dr Niang.

“We aren’t sure why, but apart from physical distance, it may be the case that some cultural boundaries also existed. Perhaps the populations using these different material cultures also lived in slightly different ecological niches.”

Around 15 thousand years ago, there was a major increase in humidity and forest growth in central and western Africa, that perhaps linked different areas and provided corridors for dispersal. This may have spelled the final end for humanity’s first and earliest cultural repertoire and initiated a new period of genetic and cultural mixing.

Dr Scerri concluded:

“These findings do not fit a simple unilinear model of cultural change towards ‘modernity.

” Groups of hunter-gatherers embedded in radically different technological traditions occupied neighbouring regions of Africa for thousands of years, and sometimes shared the same regions. Long isolated regions, on the other hand, may have been important reservoirs of cultural and genetic diversity.

“This may have been a defining factor in the success of our species.”

Team fieldwalking along the Gambia River, Senegal Credit Eleanor Scerri

The findings were published in Scientific Reports.

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