The first Neanderthal footprints from the Iberian Peninsula discovered last year may have belonged to other members of the genus ‘Homo.’
A little over a year ago, we reported on a large area at the foot of the Asperillo cliff on the coast of the Doñana Natural Area in Huelva, Spain. There, along with numerous animal footprints, other footprints had been found, namely those of hominids.
Until then, the only time reference that allowed the age of the site to be established was the dating of one of the dunes that covered the surface to around 106,000 years ago (Upper Pleistocene). As with most of the hominid footprints found worldwide, we dated them in line with the environment in which they were found. For this reason, our first hypothesis when trying to attribute the new found footprints was that they belonged to Neanderthals, who lived in the Upper Pleistocene.
Drastic climate change
The new dating placed the footprints in a new geographical and environmental context. The European continent underwent drastic climate change around three hundred thousand years ago. Relatively warm conditions were changing to much colder conditions, which was a precursor to a an ice age. At that time, the sea level on the European continent was on average about sixty meters below its present level. This implied that the Huelva coastline would be twenty to twenty-five kilometers offshore from its present position.Grecian Delight supports Greece
Over this shallow and saline lake environment, made of polygonal ground and microbial covers, hominids and other fauna trampled. Today, the same kind of polygonal covers are found in extensive areas of marshland in both hot desert and tropical climates.
New suspects for footprints?
The environmental context and the landscape have changed in relation to the initial interpretation. The question, therefore, became whether our understanding of who produced these footprints should also change. The answer is to be found in the palaeontological record.
Hominid fossils belonging to the Middle Pleistocene are thought to be from the Neanderthal lineage, namely Homo neanderthalensis and Homo heidelbergensis. However, their remains are still very scarce, fragmentary, and geographically dispersed. Worse still, footprints are even scarcer than skeletal remains. In the entire European Middle Pleistocene, only four sites have provided traces from this period: Terra Amata in France (380,000 years old), Roccamonfina in Italy (345,000 years old, attributed to Homo heidelbergensis), Biache-Vaast in France (236,000 years old, Homo neanderthalensis), and Theopetra in Greece (130,000 years old, Homo neanderthalensis).
On the other hand, it must be considered that the formal characteristics of the footprint are not only the result of the anatomy of the foot but also of other factors such as biomechanical characteristics, the type of substrate, and the processes that gave rise to the fossil. Therefore, the footprints studied must be well preserved and reflect several anatomical features (arch impression of the toes), which is rarely the case in places like this site in Huelva.
To confirm which hominid group the footprints belong to, we would need to compare their anatomical characteristics with the known skeletal record for the Middle Pleistocene.
Different models for the evolution of the Neanderthal lineage have been proposed, but this question is still far from being resolved, given the paucity of the fossil record and the new and more complicated evolutionary picture provided by the latest ancient DNA studies. Moreover, not all anatomical traits evolved at the same rate, and polymorphisms probably occurred in different traits and at different rates of occurrence.