Saturday, February 15, 2014
Earliest evidence of human footprints outside Africa discovered
Extraordinary find of 800,000 year old footprints In England makes a direct connection to the earliest humans in northern Europe
A team of scientists led by the British Museum, Natural History Museum and Queen Mary University of London have discovered a series of footprints left by early humans in ancient estuary muds over 800,000 years ago at Happisburgh in Norfolk, The footprints are direct evidence of the earliest known humans in northern Europe. The new evidence, published today in the science journal PLOS ONE reveals how the footprints were discovered and recorded on the foreshore at Happisburgh during May 2013.
The footprint surface was exposed at low tide as heavy seas removed the beach sands to reveal a series of elongated hollows cut into compacted silts. "At first we weren’t sure what we were seeing," explains Dr Nick Ashton of the British Museum "but as we removed any remaining beach sand and sponged off the seawater, it was clear that the hollows resembled prints, perhaps human footprints, and that we needed to record the surface as quickly as possible before the sea eroded it away." Over the next two weeks the surface was recorded using photogrammetry, a technique that can stitch together digital photographs to create a permanent record and 3D images of the surface. It was the analysis of these images that confirmed that the elongated hollows were indeed ancient human footprints, perhaps of five individuals. Ashton concludes "this is an extraordinarily rare discovery. The Happisburgh site continues to re-write our understanding of the early human occupation of Britain and indeed of Europe".
The analyses showed that the prints were from a range of adult and juvenile foot sizes and that in some cases the heel, arch and even toes could be identified, equating to modern shoes of up to UK size 8. Dr Isabelle De Groote from Liverpool John Moores University studied the prints in more detail. "In some cases we could accurately measure the length and width of the footprints and estimate the height of the individuals who made them. In most populations today and in the past foot length is approximately 15% of height. We can therefore estimate that the heights varied from about 0.9 m to over 1.7 m. This height range suggests a mix of adults and children with the largest print possibly being a male." The orientation of the footprints suggests that they were heading in a southerly direction.
Over the last ten years the sediments at Happisburgh have revealed a series of sites with stone tools and fossil bones, dating back to over 800,000 years. This latest discovery is from the same deposits. "Although we knew that the sediments were old, we had to be certain that the hollows were also ancient and hadn’t been created recently." Say Dr Simon Lewis, a geoarchaeologist at Queen Mary University of London. "There are no known erosional processes that create that pattern. In addition, the sediments are too compacted for the hollows to have been made recently."
The age of the site is based on its geological position beneath the glacial deposits that form the cliffs, but also the association with extinct animals. Simon Parfitt of the Natural History Museum and University College London has studied the mammalian fossils from Happisburgh. "These include an extinct type of mammoth, extinct horse and early forms of vole. Together they support an age of over 800,000 years." The site also preserves plant remains and pollen, together with beetles and shells, which allows a detailed reconstruction of the landscape. At this time Britain was linked by land to continental Europe and the site at Happisburgh would have been on the banks of a wide estuary several miles from the coast. There would have been muddy freshwater pools on the floodplain with salt marsh and coast nearby. Deer, bison, mammoth, hippo and rhino grazed the river valley, surrounded by more dense coniferous forest. The estuary provided a rich array of resources for the early humans with edible plant tubers, seaweed and shellfish nearby, while the grazing herds would have provided meat through hunting or scavenging.
So who were these humans? Fossil remains of our forebears are still proving elusive. However, as Professor Chris Stringer of the Natural History Museum explains "The humans who made the Happisburgh footprints may well have been related to the people of similar antiquity from Atapuerca in Spain, assigned to the species Homo antecessor ('Pioneer Man'). These people were of a similar height to ourselves and were fully bipedal. They seem to have become extinct in Europe by 600,000 years ago and were perhaps replaced by the species Homo heidelbergensis. Neanderthals followed from about 400,000 years ago, and eventually modern humans some 40,000 years ago."
The importance of the Happisburgh footprints is highlighted by the rarity of footprints surviving elsewhere. Only those at Laetoli in Tanzania at about 3.5 million years and at Ileret and Koobi Fora in Kenya at about 1.5 million years are more ancient. As Nick Ashton concludes "these footprints provide a very tangible link to our forebears and deep past." The work at Happisburgh continues, but as the cliffs erode, new sites are being discovered, but also destroyed by the encroaching sea. The footprints were unfortunately rapidly eroded away, but it is hoped that new footprints will be revealed in the future.
The work at Happisburgh forms part of a new major exhibition at the Natural History Museum Britain: One Million Years of the Human Story opening on 13 February 2014.