Ancient footprints on UK beach record the demise of a biodiversity hotspot

By Alison Burns and Jamie Woodward, The University of Manchester

To compare Formby Point, 18 km north of Liverpool, with the Serengeti, might seem an odd thing to do. Yet a series of footprints recorded between 2010 and 2016 and recently dated, show that if you go back around 8000 years, the region was a rich ecosystem, with humans living alongside a variety of animals, including aurochs, red deer, roe deer, wild boar, beaver, wolf, and lynx.

Coastal habitats were a key location for both humans and animals at the end of the last ice age. With sea levels lower than they are now, these provided not only resource rich landscapes, but also key passageways to new lands. Humans traveled into North America over the Bering Land Bridge during this time, and into Britain via Doggerland, an expanse of land that now sits under the North Sea between Denmark and England. As glaciers melted, sea levels also rose, and these lands were lost, and the coastlines eventually formed to look as they do today.

A human footprint in the ancient mud on Formby beach radiocarbon dated to about 8500 years ago. Photo by Jamie Woodward

Coasts are also very useful palaeontological records because they often have extensive beds of mud that allow for footprints to be effectively captured and preserved. Thousands of human and animal footprints have been observed and studied around the UK, providing key insights into the ecosystems of the past.

Our new research, published in the journal Nature Ecology and Evolution, also uses the footprints, discovered at Formby Point, in this way, but also includes a new programme of radiocarbon dating which shows that the most species-rich footprint beds at Formby Point are much older than previously thought, dating back to around 9,000 years ago, meaning we can use the footprint beds create a picture of a key period of change in the natural history of Britain from Mesolithic to Medieval times.

Overall, what the footprint beds show is that, as global sea levels rose rapidly after the last ice age around 9000 to 6000 years ago, humans formed part of rich intertidal ecosystems alongside other large animals. Following this period, agriculture-based societies formed and there was a striking fall in the large mammal populations. This can be seen by the fact that human footprints dominate the Neolithic period and later footprint beds.

A footprint bed from the Mesolithic about 8500 years ago covered in red deer hoofprints. View from Formby beach looking south towards Liverpool. Photo by Jamie Woodward

The observed decline in large mammals could be the result of several factors including habitat shrinkage following sea level rise and the development of agricultural economies, as well as hunting pressures from a growing human population. This new record poses important questions of the conventional archaeological and fossil records.

Assessing the threats to habitat and biodiversity posed by rising sea levels is a key research priority for our times – we need to better understand these processes in both the past and the present. Well-dated fossil records for this period are absent in the landscapes around the Irish Sea basin, making these footprint beds particularly important. This research shows how sea level rise can transform coastal landscapes and degrade and disconnect important ecosystems. These are lessons that will be vital for understanding not only past ecosystem changes, but also ones that are ongoing in the present.

For more information on these findings, see related BBC News Piece.

About the authors: Dr Alison Burns was a PhD student in Archaeology and Geography at The University of Manchester. Jamie Woodward is Professor of Physical Geography at the University of Manchester.