Based on the behavior of the zeolithic minerals (a mineral type found in lava) in the deposits on which the footprints are impressed, the researchers say the tracks were left when the compaction of the volcanic flow of ash, pumice, and rock fragments was not yet completed. "It is thus reasonable to infer that these humans actually witnessed the eruption," said Mietto.
The theory is supported by the fact that all three tracks lead in the same direction, away from the volcano's main crater.
The Oldest Confirmed Footprints
Up to now, only a poorly preserved and isolated footprint discovered in Terra Amata in France has been attributed to a human track maker. The famous footprints of Laetoli in Tanzania date back 3.5 million years, but they are referred to as hominids and not true humans: Genus Homo.
True human footprints from the Pleistocene era (dating back 1.6 million years) are known from a few other localities. Two footprints believed to be 117,000 years old were found on a South African sand dune. Several footprints were preserved in cave sediments in France. And a series of footprints dating back to the late Paleolithic age were discovered inside a cave in Toirano, Italy.
The latest discovery is particularly rare because the footprints are preserved in a subaerial setting rather than caves. "Whereas tracks from the late Pleistocene cave habitats are quite well-known, the Roccamonfina discovery suggests the potential to find other human and vertebrate tracks in older, subaerial, paleo-environments," said Mietto.
A summary of the research team's findings appears in the current issue of the science journal Nature.
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