Abstract

Homo naledi is a previously unknown species of extinct hominin discovered within the Dinaledi Chamber of the Rising Star cave system, Gauteng, South Africa. This species is characterized by body mass and stature similar to small-bodied human populations, with a small endocranial volume similar to australopiths. Cranial morphology of H. naledi is unique, but most similar to early Homo species including H. erectus, H. habilis, or H. rudolfensis. While primitive, the dentition is generally small and simple in occlusal morphology. H. naledi has humanlike manipulatory adaptations of the hand and wrist. It also exhibits a humanlike leg and foot. These humanlike aspects are contrasted in the postcrania with a more primitive or australopith-like trunk, shoulder, fingers, pelvis, and proximal femur. Nonetheless, the shared derived features that connect H. naledi with other members of Homo occupy most regions of the H. naledi skeleton and represent distinct functional systems, including locomotion, manipulation, and mastication. With at least 15 individuals and most skeletal elements represented by multiple specimens, this is the largest assemblage of a single species of hominins yet discovered in Africa. To date we have recovered more than 1, 700 specimens, with comprehensive representation of skeletal elements across the lifespan, and from multiple individuals. Regardless of the fact that the Dinaledi Chamber is currently undated, H. naledi highlights gaps in our understanding of ancient Homo across the vast geographic span of the African continent. The tree of Homo-like hominins is far from complete: we have missed key transitional forms and lineages that persisted for hundreds of thousands of years.