Human-like helpless infancy in Homo erectus and Homo floresiensis plus related claims

A long period of helpless infancy after birth is one of the most unique and mysterious characteristics in human life history. Because this trait is intimately linked to rapid postnatal brain growth, which is essential to produce the large human brain, researchers have long been interested in when it evolved. In a new study, researchers introduce a new method that serves as a direct indicator of helpless infancy and can be easily applied to the existing hominin fossils. They focused on a type of asymmetric cranial deformity that is a direct outcome of helpless infancy. Because this deformity tends to be retained later in life, it can be a signature of helpless infancy even when found in adult cranial fossils. The results demonstrated that extensive cranial deformation is not present in great apes. They found that some Indonesia Homo erectus and Homo floresiensis skulls exhibit huma-like severe cranial deformation. These support a deep evolutionary origin of hominin helpless infancy,…