The mystery behind the more than 1,200 barefoot human footprints preserved in wet clay for more than 4,500 years might have been cracked thanks to a group of archaeologists who believe they have identified the cave’s first human explorers.
Over 1,200 human footprints were found in what is one of the largest cave complexes in the world and they are now beginning to yield their secrets to experts who have scanned them with new tech that shows them to be over 4,500 years old and often intact despite being imprinted on wet clay on the ground inside the cave.
In 1969, a group of speleologists belonging to the Edelweiss group – one of Spain’s oldest speleologist organisations – went into the Palomera cave, which is located in the karst complex of Ojo Guarena, in the municipality of Merindad de Sotoscueva, in the northern Spanish province of Burgos.
It is a labyrinthine maze of galleries and caves. About 1,200 metres (4,000 feet) into the cave, considered the largest of Spain and one of the largest in the world and made up of six distinct levels and more than 100 kilometres (62 miles) of underground galleries, the explorers found two galleries with barefoot human footprints on the ground.
Dr Ana Isabel Ortega, 61, an archaeologist at the National Centre of Investigation into Human Evolution (Centro Nacional de Investigacion sobre la Evolucion Humana; CENIEH) and the Atapuerca foundation, explained to Real Press in an exclusive interview that “the speleologists were surprised when they saw so many footprints and when they realised that they were barefoot they thought that there might have been other, older prehistoric speleologists who had explored the cave before.”
Dr Ortega said: “The speleologists were aware of the importance of this discovery and went back on their steps to avoid destroying more footprints.” These footprints are very delicate as they were done in wet, soft clay and they can be easily damaged.
So the speleologists called the authorities, who decided to protect the two galleries with the footprints, building a kind of corridor that avoided them so that people could investigate them properly without risking damaging them.
The expert explained that the first attempts to investigate the footprints took place in the 1970s, but while making replicas of the footprints using plaster, “they realised that they were also removing part of the surface when peeling off the plaster”, so they decided to stop doing it.
It was not until 2012 that technological advances allowed the experts to create models of the footprints without damaging them.
The archaeologists used a 3D scanner and recorded models of the footprints. They are still investigating them as there are over 1,200 footprints located in both galleries, which have been renamed, since the discovery, the Gallery of Footprints.
Ortega said: “Thanks to the 3D scans and the digital photography, in combination with GIS techniques, we have managed to identify more than 1,200 footprints at the site.” GIS stands for Geographic Information Systems. The technology helps archaeologists recall information and map excavation sites.
While scanning all the footprints only took a day, processing the data is by far more complicated, as every detail about every footprint needs to be evaluated individually.
The research also included Carbon 14 tests – also known as radiocarbon dating, a technique used to date various objects – on the remains of torches found in the cave and on the way to the Gallery of Footprints.
Six of the samples match the route taken by the cave’s early explorers, between 4,200 and 4,500 years ago, so it is believed that the footprints are also that old, which would put them in the Chalcolithic era – also known as the Copper Age.
In other parts of the caves and the karst complex, the experts have also found samples that date back between 6,200 and 6,600 years, from the Neolithic era, as well as three samples from between 7,700 and 7,800 years, during the Mesolithic era. The oldest sample they have found is 19,000 years old, from the Upper Palaeolithic period.
The experts determined that there are more footprints depending on the location inside the cave. While in the lateral part, near the wall, the footprints are more loose-fitting, in the centre, they were found to be spaced more closely together, which makes it more difficult to study them and to determine which one belongs to which individual.
So the researchers decided to focus on the lateral footprints, and studied 39 of them and their seven tracks.
According to the researchers, those footprints belong to a group of between 10 and 11 individuals, probably men because of the physiognomy information that was revealed thanks to their research into the footprints that harnessed the new technology.
The footprints belong to individuals weighing between 80 and 90 kilogrammes (176 and 198 lbs), so it is believed that they were tall adults or teenagers, with a height of between 1.72 and 1.85 metres (5.6 and 6 feet).
Dr Ortega explained that based on these measures, “we believe that they were men, although there might be a tall strong woman among them, but they were mostly men.”
Now the experts are attempting to determine what these people were doing in the cave and what purpose it served. Dr Ortega said: “I believe it was a party of explorers who went in to find out whether they could turn it into a place to do cave paintings or other rituals but they did not like what they saw.”
Dr Ortega said: “They might be some of the first explorers.” She added: “Maybe the desire to discover the unknown is in our DNA and we have always had it.”
She said: “In the Prehistoric world, territory was everything, not only outdoor territory but also indoor territory.”
Dr Ortega said that the humans who lived during the Chalcolithic era were some of the first farmers in history and they already had decorations on their clothes and hierarchies in society.
The investigation into the cave and the footprints is ongoing.