A few thousand years apart may seem banal in the millions covered by prehistory. However, a dating of 150,000 years or so in hominid tracks may force us to change some pages of this period and even the chronology of human evolution. A disagreement of these characteristics has occurred with the hominid footprints found in El Asperillo, a Huelva coastal enclave located between the beaches of Mazagón and Matalascañas. A study published in Scientific Reports, argued that the age of these footprints was 295,800 years, so they could have been left by a previous Neanderthal lineage and represent, according to the authors, “a crucial record for understanding human occupations in Europe in the Pleistocene.” A new dating work published in Quaternary Science Reviewssets the age of the footprints at 151,100 years, ensures that they are from Neanderthals (the oldest) and incorporates remains of stone tools used by them to manipulate the meat of the gigantic animals that cohabited this environment, today the Doñana Natural Park, to which the hominids went temporarily to hunt.
Finding a footprint preserved for more than 150,000 years is a difficult paleontological prize to win. These simple footprints or traces, studied by ichnology (a discipline of paleontology that studies evidence of activity left in sediments or rocks by living organisms), can shed light on who or what left it, the living environment, where it came from and where it was headed, what for, what it fed on, how it was related to its world… The storms three years ago in Matalascañas allied with researchers and revealed evidence of biological activity, including human activity, left behind millennia ago in an area of beach and cliffs that had remained intact. José María Galán, a guide in the Doñana National Park and an expert tracker of the traces of history, was the first to point out the uniqueness of the vestige existing in the sands of Huelva.
The new deposit, called MTS (Matalascañas Trampled Surface o Matalascañas Footprint Surface) and described for the first time by this same international team in 2020, includes footprints and traces of large mammals such as Palaeoloxodon antiquusstraight-tusked elephants similar to their modern-day relatives from the African forests, but up to four meters tall; Sus scrofa scrofawild boars that tripled the size of those that exist today; Bos Primigenius, bulls up to two meters in height and 1,500 kilograms in weight; deer and wolves. Also delicate fossils of bird tracks and roots, as well as invertebrate burrows. But the most substantial traces are from hominids that took refuge in southern Europe from the glaciation of the rest of the continent.
The study published by Scientific Reports He attributed them to about 300,000 years old, in the Middle Pleistocene. “It opened up a new geochronological scenario, compared to previous studies, and raised questions about the age of MTS. [yacimiento de Matalascañas] and, consequently, of the possible species of hominids that could have produced the tracks”, warns the new work.
This “new scenario” did not fit with the rest of mammal tracks in the same geological layers or with the materials found. Therefore, the team led by Carlos Neto De Carvalho, a paleontologist from the Naturtejo UNESCO Global Geopark and from the University of Lisbon, Fernando Muñiz, a geologist and ichnologist from the University of Seville, and Luis Miguel Cáceres, a geologist from the University of Huelva, among others, kept his investigation open and preferred to wait for the results of an exhaustive dating with optically stimulated luminescence (OSL) developed by the Burgos laboratory National Center for Research on Human Evolution (CENIEH). The recently published conclusion “ensures the attribution of the tracks to Neanderthals, the only known hominids to have been present in the Iberian Peninsula during the MIS6-5 transition.” [Pleistoceno medio]”.
“The only humans present at that time in the Iberian Peninsula and who left traces of their activity were Neanderthals. They are the oldest traces of this species of humans found in Europe and in the world, since only the Neanderthals occupied Europe and the border area with Asia at that time”, says Muñiz.
Neto de Carvalho points out that, beyond being or not the oldest traces of this species, still present in our DNA, the key is precise dating: “The most important thing is not even antiquity but the fact that they are the first traces of chronologically well-defined Neanderthals, the lithic industry found in their environment and which is the only evidence of direct interaction with the animals with which they fed”.
In this sense, the study details that the typical Mousterian lithic industry (126 stone tools belonging to the Middle Paleolithic and related to the homo neanderthalensis) reflects that the selection of raw materials was made in outcrops located near the area where the tracks were left. “Possibly, they were manufactured right there with the lithic resources that the environment offered, such as quartzite pebbles,” explains Muñiz.
Luis Miguel Cáceres specifies that “these lithic resources are scarce in the immediate area, so the simplest thing was to bring them from where they abound.” “These abundant sources are not too far away, they are the terraces of Tinto or Guadalquivir, located about 30 km to the northwest, the former, and the latter to the northeast.”
The origin of the stones and the place of use, according to the investigation, confirms that the site “cannot be seen as a settlement, but rather as a place of passage for fauna, including Neanderthals, where some human individuals carried out temporary activities such as food procurement and meat processing.
Cáceres adds that “the Neanderthals did not have properly stable settlements, but moved through the territory taking advantage of the resources that the natural environment could offer them. The caves served as a temporary and probably seasonal settlement.
“The seasonal lacustrine system between the coastal dunes [que hoy forma parte de Doñana] it was a congregation site where different mammals, including hominids, and birds converged, presumably, to obtain water and food resources and, possibly, also for reproduction”, confirms the study in contrast to the theories that indicate that the area could be a stable settlement. Previous work suggested this hypothesis with the attribution of up to 87 footprints to a social group of different ages.
“Stalking Behavior”
“The MTS [yacimiento de Matalascañas] represents an extraordinary case where the Neanderthal tracks occurred at the same time or shortly after the other tracks of large herbivores. The archaeological evidence (stone instruments) and the tracks of the animals together with those of the slow march observed in the tracks of Neanderthals allow us to infer a possible stalking behavior. The presence of associated stone tools is convincing evidence that they were used for animal processing. They are not evidence of settlement, but rather of a place of passage, both for fauna and for Neanderthals”, the study concludes. “The Neanderthal tracks were produced at exactly the same time as the other tracks with a difference of hours or a few days,” explains Neto and confirms Cáceres.
Both studies were dated using optically stimulated luminescence (OSL), a technique that, as explained by Alicia Medialdea, a CENIEH physicist specializing in this method, “provides the age of the sediments based on the dose of ionizing radiation they have received the quartz and feldspar grains. This radiation comes primarily from the uranium, thorium, and potassium in its environment. The accumulated dose will depend on the concentration of these radioelements in the medium and on the time that the mineral grains have been receiving that radiation. This relationship will be the one that gives the time that a specific sediment has been buried”.
The technique is reliable, defends Medialdea, and it has been carried out correctly in the two studies, which have shown an age difference of 150,000 years on different samples taken from the same area, but not from the same point. “This method”, explains the physicist, “dates the last time the sand grains were exposed to sunlight, assuming that this was the last time they underwent a transport process before being buried. In cases where transport was very fast, in a very turbid environment or overnight, it is possible that not all the grains were exposed to light during their last transport and, therefore, did not bleach their luminescent signal. This would mean that, at the same level, there would be a mixture of sand grains that received sufficient light during the last transport, and would be valid for estimating their age, and others, not bleached, that would maintain a residual signal. This mixture, which we call partial bleaching, can lead to overestimations of age.”
And he adds: “There are many different sedimentary profiles in the Matalascañas cliff and the two groups have not treated exactly the same thing. The samples measured by both groups are not exactly the same. It may be that the datings are correctly done, but it is necessary to review the interpretation of the stratigraphy to better understand how the Matalascañas cliff was formed“.
In this way, the physical method used (measurements of luminescence and concentration of radioelements in the medium) requires exhaustive analysis and interpretations in order to estimate when the sediment was deposited and buried. “Now that we have dates in the area, it is time to work to reinforce them, relying on the associated lithic industry and on faunal tracks,” concludes Medialdea.
In the last published study, researchers from the Naturtejo Geopark, Seville, Huelva, Lisbon, Coimbra, Burgos, Barcelona, Murcia and Gibraltar participated.
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