Rare glimpse into our ancestors
Researchers found that a dramatic climate event with a sudden drop in average temperatures, severe enough to halt the development of woodland, had no substantial impact on human activity at Star Carr – a middle Stone Age archaeological site in North Yorkshire, dating to around 9,000 BC.
The study sheds new light on significant debate about the sensitivity of hunter-gatherer societies to environmental change.
The prehistoric community, who persevered through the cold snap that would last more than 100 years, left a plethora of worked wood, animal bones, antler headdresses and flint blades buried in layers of mud as evidence of their continued productivity and endurance.
Excavations at the site were directed by Dr Chantal Conneller, Newcastle University, who explained: “We have been working at Star Carr for about 15 years and the site has produced an incredibly rare glimpse into the world of our Mesolithic ancestors who lived at the end of the ice age, about 11,000 years ago.
“Putting this archaeological data into the context of the climate and environment is very exciting and shows that we need to keep an open mind when thinking about the effects of extreme climate on early populations.”
Simon Blockley, Professor of Quaternary Science at Royal Holloway, who led the climate modelling, said: “It has been argued that abrupt climatic events may have caused a crash in Mesolithic populations in Northern Britain, but our study reveals, that at least in the case of the pioneering colonisers at Star Carr, early communities were able to cope with extreme and persistent climate events.
“We found people were in fact far more affected by smaller, localised changes to their environment - Star Carr was once the site of an extensive lake and people lived around its edge.
“Over time the lake gradually became shallower and boggier, turning into fenland which eventually forced settlers to abandon the area.”
The early Holocene, the current geological epoch which started some 11,500 years ago when the glaciers began to retreat, was dominated by climatic instability characterised by extreme weather events triggered by ice-ocean interaction during the final wastage of the northern hemisphere ice sheets.
The rich archaeological record at Star Carr gave the researchers the rare opportunity to directly compare the palaeoclimate record with evidence of human activity through time in the same location.
The researchers examined human activity by looking at archaeological remains recovered from layers of wetland deposits at the edge of the extensive former lake basin in the Vale of Pickering.
They found evidence of houses, large wooden platforms built on the lake edge and large quantities of artefacts and bones preserved in the lake muds and these were radiocarbon dated. Pollen, macrofossils and isotopes taken from lake sediment cores allowed the researchers to build a high-resolution picture of the climate of the area over thousands of years.
The team identified two episodes of extreme cooling which saw average temperatures drop by more than 3 degrees in the space of a decade. The first of these events occurred very early after humans began to return to the area after the last ice age.
The evidence indicates that these conditions may have affected the activities of a community in the nascent stages. However, the second of these events, which occurred later when the community was more established, appears to have had very little impact.
Dr Conneller, who led the excavations while working at the University of Manchester, added: “By this time, the site had become a special place for these people. Our evidence suggests that Star Carr played a very important role for these people, so much so that they weren’t prepared to abandon it when times were hard.”
The study was carried out by researchers based at Royal Holloway, University of London, and the University of York. It was funded by the European Research Council, Historic England, the Natural Environment Research Council, The British Academy, The Vale of Pickering Research Trust, and the Universities of York, Manchester and Chester.
Reference: “The resilience of postglacial hunter-gatherers to abrupt climate change”, published in Nature Ecology and Evolution, 26 March 2018. doi:10.1038/s41559-018-0508-4
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