Fossils discovered in a cave in Casablanca and dated to around 773,000 years ago fill a major gap in the African hominin record and offer rare insight into a population that lived just before the split between modern humans and Neanderthals–Denisovans. The mandible of an archaic human who lived about 773 000 years ago excavated at Grotte a Hominides in Casablanca. / Ph. J.P. Raynal, Programme Prehistoire de Casablanca ‹ › Fossils unearthed in a Moroccan cave and dated to nearly 800,000 years ago are reshaping scientists' understanding of the deep origins of Homo sapiens, according to a new study published Wednesday in Nature. The study is based on fossil discoveries made in Casablanca, inside a cave known as Grotte à Hominidés. The remains, dated to around 773,000 years ago, include lower jawbones from two adults and a toddler, along with several teeth, cervical and thoracic vertebrae, and a fragment of a thigh bone (femur). «The last common ancestor» Together, these remains fill a major gap in the African fossil record of hominins, the species in the human evolutionary lineage, covering a poorly documented period between about one million and 600,000 years ago. According to the researchers, the fossils likely represent an African population that lived shortly before the evolutionary split between the lineage that gave rise to Homo sapiens in Africa and the lineages that later evolved into Neanderthals and Denisovans in Eurasia. «I would be cautious about labeling them as 'the last common ancestor'», said lead author Jean-Jacques Hublin, a paleoanthropologist at the Collège de France and the Max Planck Institute for Evolutionary Anthropology. «But they are plausibly close to the populations from which later African, Homo sapiens, and Eurasian, Neanderthal and Denisovan, lineages ultimately emerged». The fossils were recovered in a secure stratigraphic context and dated using advanced magnetostratigraphy, making them among the most reliably dated hominin remains of this age in Africa. The researchers interpret them as belonging to an evolved form of Homo erectus, an archaic human species that emerged in Africa around 1.9 million years ago before spreading into Eurasia. A mosaic of traits Anatomically, the Moroccan fossils show a «mosaic» of traits, as described by Hublin. They retain primitive features seen in early Homo species while also displaying more derived characteristics reminiscent of later Homo sapiens. Hominins from this period had body proportions broadly similar to modern humans, but with smaller brains, according to the study. While some similarities exist with Eurasian archaic hominins, the Moroccan fossils do not belong to those lineages. «The ThI-GH hominins are similar in age to Homo antecessor, yet are morphologically distinct», the study notes. Homo antecessor, discovered in Spain, had previously been proposed as a possible ancestor of modern humans. The new Moroccan evidence suggests that by this time, regional differences between Africa and Europe were already established, with European populations showing stronger affinities toward the Neanderthal lineage. The study also sheds light on the harsh environment these early humans inhabited. Although they were capable of hunting prey, they lived in a dangerous landscape dominated by large carnivores, including big cats and hyenas. Evidence on the femur indicates it was gnawed and bears tooth marks, pointing to consumption by a large carnivore. «Only the femur displays clear evidence of carnivore modification», Hublin explained. «The absence of tooth marks on the mandibles does not imply that other parts of the bodies were not consumed by hyenas or other carnivores». Crucially, the Moroccan fossils strengthen the case for an African, rather than Eurasian, origin of Homo sapiens. To date, all securely dated Homo sapiens fossils older than 90,000 years have been found in Africa or at the gateway to Asia. Morocco already occupies a central place in this narrative with the Jebel Irhoud fossils, dated to over 300,000 years ago and considered the oldest known remains of our species.
