Around 350,000 years ago, a group of ancient humans left behind mysterious footprints on a fresh layer of volcanic debris in Italy. Known as the “Devil’s Trails,” these tracks have puzzled researchers ever since. A recent study published in Quaternary offers a deeper look into who these individuals might have been, revealing that their journey across the dangerous terrain could hold clues about the ancient humans of Europe. But identifying the species behind the tracks is no easy task.
The Devil’s Trails: A Walk on Volcanic Ash
In southern Italy, the eruption of the Roccamonfina volcano released an intense flow of pyroclastic material—molten rock and ash—into a nearby valley. As the material cooled, it formed a soft, yet solid surface where a group of humans walked, leaving behind a trail of prints. This rare discovery has sparked curiosity about the people who made the tracks, especially since volcanic eruptions like this were once seen as catastrophic events that were challenging to survive.
The footprints were discovered in a region filled with ignimbrite, a type of rock formed from volcanic debris. Though the terrain was steep and uneven, the tracks are remarkably clear, offering a glimpse into the past. This evidence suggests that these humans walked across a volcanic landscape that had only recently cooled, likely when it was still soft enough to leave imprints, but had hardened enough to be traversed.
Estimating the Physical Characteristics of the Trackmakers
To identify the physical characteristics of the people who made these tracks, researchers turned to a familiar method: analyzing the footprints to estimate their size and body weight. However, this wasn’t an easy task. The tracks were left on an uneven surface that complicated traditional calculations. Previous formulas used to determine human size based on footprints are generally applied to prints left on flatter terrain, and the volcanic surface created challenges for accurate measurements.
After accounting for the uneven nature of the landscape, researchers calculated that the trackmakers were likely between 152.9 and 176.7 centimeters (5 feet to 5 feet 9 inches) tall, and weighed between 55.5 and 64.6 kilograms (122.4 to 142.4 pounds). These estimates align closely with the body proportions of Homo heidelbergensis, a species that roamed Europe around the same time. The findings in Quaternary further suggest that these individuals were likely part of a mixed group, potentially consisting of two women or children, and one adult male.
The Uncertainty of Human Origins: A Closer Look at Homo Heidelbergensis
The study published in Quaternary acknowledges that while the data offers some insights, it also presents many uncertainties. The researchers note,
“On the whole, the available data enable us to only formulate rather vague conclusions and to observe that the body size of the [Devil’s Trails] trackmakers falls in the wide variation range of H. heidelbergensis.”
This suggests that while the body size estimates fit within what is known about H. heidelbergensis, further research is needed to definitively link the tracks to this species.
H. heidelbergensis was an important ancestor to both Neanderthals and modern humans, and its physical characteristics vary widely across different populations. Some individuals of H. heidelbergensis were much taller than the group that left the Devil’s Trails, with records showing that some reached heights of up to 181.6 centimeters (5 feet 11 inches). This range of physical diversity could explain the variation in body size among the tracks, adding a layer of complexity to the identification process.
What Can We Learn from the Devil’s Trails?
While the discovery of these ancient footprints offers fascinating insight into the past, it also raises more questions than answers. The tracks suggest that these early humans were able to adapt to harsh environments, possibly as they navigated volcanic landscapes. Their ability to alter their gait and step carefully on a soft, slippery surface hints at their advanced coordination and awareness.
But the ultimate question remains: who were these humans? Could they be direct ancestors of modern humans, or are they a branch of humanity that has since gone extinct? The Devil’s Trails, along with other archaeological evidence from the time, could eventually help clarify the evolutionary path that led to modern Homo sapiens. However, as the study in Quaternary points out, more research is necessary to make more concrete conclusions.
