Comparative 3D Shape Analysis of the Iwo Eleru Mandible, Nigeria

The Iwo Eleru skeleton is the only Pleistocene human fossil currently known from Western Africa. Previously, we showed morphological affinities of the Iwo Eleru cranial remains with Pleistocene archaic African specimens, consistent with former interpretations of this specimen. Those results suggested deep population substructure in Africa and a complex evolutionary process for the origin of modern humans, potentially involving hybridization between Later Stone Age modern human populations and late surviving archaic lineages. Here we conduct a geometric morphometric comparative analysis of the Iwo Eleru mandible, so as to shed further light on the specimen’s morphology and evolutionary relationships. We used twenty-five three-dimensional landmark coordinates, collected from a comparative sample comprising Pleistocene and Holocene Homo sapiens, as well as Homo neanderthalensis and Eurasian Middle Pleistocene Homo samples. Our analysis also included the enigmatic Banyoles and Tabun 2 individuals. Results show that the Iwo Eleru mandible is most consistent with the shape variation found in African Homo sapiens from Holocene and Epipaleolithic contexts. Its large size aligns it more closely with our North African Epipaleolithic and some of our Pleistocene samples. These findings are consistent with the temporal and geographic origin of the Iwo Eleru skeleton. The Banyoles specimen is closest to our Upper Paleolithic Homo sapiens sample, supporting previous assessments. Tabun 2 showed affinities to archaic samples but did not align clearly with any of the groups included here, similar to previous results.