A new archaic human skull discovered in a cave in Portugal could give incredible insight into where the Neanderthals, our stockier ancient cousins, came from. It is thought that the discovery could help explain which other species of archaic human evolved into Homo neanderthalensis when they appeared in Europe some half a million years ago.

Our ancestors were not the first species of human to migrate out of Africa and into Asia and Europe. It is thought that multiple other archaic humans made the journey, including Homo ergaster some 2 million years ago and Homo heidelbergensis, whose ancestors that remained in Africa eventually gave rise to our species.

But there has been a debate among paleoanthropologists as to which of these species eventually gave rise to Neanderthals, which came to dominate much of Eurasia before we arrived on the scene around 40,000 years ago. This latest find of an archaic human cranium in Portugal, published in the Proceedings of the National Academy of Sciences, may help shed some light on this evolutionary anomaly.

^{Virtual reconstruction of the skull found in Portugal. Javier Trueba}

It seems to show a mixture of features never before seen in a fossil human, with some of them distinctly similar to the Neanderthals that eventually inhabited the region, while others seem more archaic. While other ancient human fossils have been found in Europe, what sets this discovery apart is the fact that not only was it discovered in situ with a whole host of tools and other fossil animal bones, but more importantly it can be accurately dated to 400,000 years ago.

It makes the find not only the oldest fossil human skull ever discovered in Portugal, but also the westernmost human fossil ever found in Europe dating from this period. “This is an interesting new fossil discovery from the Iberian Peninsula, a crucial region for understanding the origin and evolution of the Neandertals,” explains co-author Rolf Quam, an associate professor of anthropology at Binghamton University in New York.

As it shares similarities with other fossils unearthed across the continent – from Spain to France to Italy – it is thought that it could help explain the diversity in archaic human appearances throughout Europe. This may aid researchers in building a more detailed picture of the evolution of human species during this time, and potentially help explain where, and when, Neanderthals came into being.

^{The skull was found alongside an array of Acheulean hand axes in the Aroeira cave. Rolf Quam}