I remember reading a short announcement in 2003 about the discovery of 385,000–325,000 years old human-like footprints near the Roccamonfina volcanoes in southern Italy. We haven’t found many paleo-footprints, so any discovery is welcomed with excitement and of course with controversy. Some of the most notable paleo-footprints are the 3.5 million year old prints from the Laetoli ash bed in Tanzania (which are in danger of being destroyed), the Pleistocene footprints from Langebaan, South Africa and another set from the same era from Willandra Lakes, Australia. There’s also the highly curious 40,000 year old Toloquilla footprints in Mexico.
The three sets of prints from Roccamonfina show that these individuals were fully bipedal and were navigating a steep descent. The tracks have some sharp hairpin turns, indicating at times they were negotiating some precarious moments. There’s even evidence of slipping, an occasional hand print shows up from time to time, suggesting someone wiped out a couple times.
The authors also measured the dimensions of the tracks and estimated that the individuals who made them were no taller than 1.5 meters in height, or 4 feet 11 inches. Again, they were fully bipedal but didn’t have a completely modern human gait. The authors were careful and didn’t get into a discussion about exactly which archaic Homo species made these tracks. At this time in Europe Homo heidelbergensis is thought to be the dominant species. The authors were also cautious and warned that the dating of the volcanic tuffs that the trackways were made on are provisional and preliminary.
I haven’t read anything about the footprints until yesterday, when I saw that Dienekes shared a citation to this new paper, “Oldest human footprints dated by Ar/Ar.” The authors of the new paper criticize that the previous authors relied on an old and imprecise K–Ar date. They instead decided to do a detailed 40Ar/39Ar dating from a sample collected directly from the footprint-bearing layer (about 5 meters away, actually). A whole range of dates were ultimately calculated, from 332,000 ± 5,000 to 403,000 ± 5,000 years ago, but a tightly grouped peak of dates clustered around 340–348,000 years ago. The authors calculated the best fit a Gaussian distribution centered at 344.5 ± 5,600 years ago.
With this slightly more refined date, we now know that the footprints were made awfully close to the Climatic Termination IV, a time at which the global ecosystem was making transition between a glacial maximum and the sudden establishment of warmer conditions…. Providing us a window into several minutes of archaic human activity during a shift in ecological and paleoclimatic conditions of the Middle Pleistocene.
- Paolo Mietto, Marco Avanzini, Giuseppe Rolandi (2003). Palaeontology: Human footprints in Pleistocene volcanic ash Nature, 422 (6928), 133-133 DOI: 10.1038/422133a
- S SCAILLET, G VITASCAILLET, H GUILLOU (2008). Oldest human footprints dated by Ar/Ar Earth and Planetary Science Letters DOI: 10.1016/j.epsl.2008.08.026