Humans
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Around 350,000 years ago, a now-extinct volcano in southern Italy violently erupted, spewing ash high into the atmosphere and filling a nearby valley with molten pyroclastic material. As this hellish discharge cooled, a mysterious group of ancient humans went for a stroll along the newly formed volcanic terrain, leaving behind a trail of footprints in the soft rock.
The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.Dubbing these prehistoric prints “Devil’s Trails”, a team of researchers has now analyzed the tracks to learn more about the hominids who made them. Found on a slope produced by the pyroclastic flow ejected by the Roccamonfina volcano, the impressions appear to have been made by at least four individuals of varying sizes and body weights.
To identify the species that blazed the devilish trail, the study authors applied a series of equations that have previously been used to estimate total body height and mass of ancient humans from their footprints. However, because most of these formulas are designed to extract data from prints left on relatively flat ground, adapting them to the tracks on the steep terrain surrounding Roccamonfina proved somewhat problematic.
According to the researchers, the footprints were likely produced at a time when the ignimbrite – or pyroclastic flow deposit – was still soft but had cooled down enough to be walked on. In addition to being steep and uneven, this brand-new promenade would also have been wet and slippery, which caused the ancient trackmakers to alter their gait and the placement of their feet.
Consequently, none of the established equations could give reliable values for the prehistoric walkers’ physical dimensions, and outcomes varied wildly depending on which formula was applied. However, after carefully selecting a series of the most appropriate equations and compiling all of their results, the study authors determined that the four trackmakers are likely to have all weighed between 55.5 and 64.6 kilograms (122.4 to 142.4 pounds) and ranged from 152.9 to 176.7 centimeters (5 foot to 5 foot 9 inches) in height.
Overall, the Devil’s Trails were made by individuals with an average weight of 60 kilograms (132 lbs) and height of 166 centimeters (5 ft 3").
Happily, these characteristics match up well with those estimated for an extinct human species called Homo heidelbergensis, which roamed Europe at the time of the eruption. A common ancestor to both Neanderthals and modern humans, H. heidelbergensis has been hypothesized to have stood at around this height, although bones found in Spain suggest that some individuals may have reached a stature of up to 181.6 cm (5 ft 11").
Based on the dimensions of the various tracks, the researchers go on to speculate that the group may have consisted of two women or children and at least one adult male, although their data is not precise enough to say this for sure or give any more detailed information about the ancient hikers.
“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,” write the authors.
The study has been published in the journal Quaternary.
