Evolutionary development of the Homo antecessor scapulae (Gran Dolina site, Atapuerca) suggests a modern‑like development for Lower Pleistocene Homo

Two well‑preserved, subadult 800 ky scapulae from Gran Dolina belonging to Homo antecessor, provide a unique opportunity to investigate the ontogeny of shoulder morphology in Lower Pleistocene humans. We compared the H. antecessor scapulae with a sample of 98 P. troglodytesand 108 H. sapiens representatives covering seven growth stages, as well as with the DIK‑1‑1 (Dikika; Australopithecus afarensis), KNM‑ WT 15000 (Nariokotome; H. ergaster), and MH2 (Malapa; A. sediba) specimens. We quantified 15 landmarks on each scapula and performed geometric morphometric analyses. H. sapiens scapulae are mediolaterally broader with laterally oriented glenoid fossae relative to Pan and Dikika shoulder blades. Accordingly, H. antecessor scapulae shared more morphological affinities with modern humans, KNM‑WT 15000, and even MH2. Both H. antecessor and modern Homo showed significantly more positive scapular growth trajectories than Pan (slopes: P. troglodytes = 0.0012; H. sapiens = 0.0018; H. antecessor= 0.0020). Similarities in ontogenetic trajectories between the H. antecessor and modern human data suggest that Lower Pleistocene hominin scapular development was already modern human‑like. At the same time, several morphological features distinguish H. antecessor scapulae from modern humans along the entire trajectory. Future studies should include additional Australopithecus specimens for further comparative assessment of scapular growth trends.The “Juan de la Cierva Formación” program (FJCI-2017-32157), from the Spanish Ministry of Science, Innovation, and Universities, funds DGM. Field seasons are supported by the Consejería de Cultura y Turismo of the Junta de Castilla y León and the Fundación Atapuerca. Data collection efforts were funded by the US National Science Foundation (BCS-0824552), The Leakey Foundation, and The Wenner-Gren Foundation. Ministerio de Ciencia, Innovación y Universidades funded this research through the project PGC2018-093925-B-C31.Peer reviewe