Abstract:

The shape variability of human lower limbs is one of the core topics in human evolutionary and locomotion anatomy, and it provides clues about human activities and labor in different subsistence. However, evaluations of knee morphological function analysis are commonly conducted on the distal femora and proximal tibiae, while patellae, as the essential components of the knee joint, have not been observed and evaluated with the morphological methods until the recent decade. From the anatomic perspective, dragged by soft tissues such as the quadriceps muscle group, patellar tendon, and medial and lateral patellar retinaculum, the patella can be shaped in various morphological characteristics in different locomotive preferences. Meanwhile, the constantly attach to the distal femur during flexion and extension also adjusts the articular surface of the patella. According to these assumptions, the morphological variation of patellae can theoretically manifest the development of these muscles and ligaments and the force preference in lower limb activities. As a significant site of Dingsishan Neolithic culture, the Huiyaotian site reveals a typical hunting-gathering subsistence in Southern China. The site locates on the first terrace near to the Yongjiang River in Qingxiu District of Nanning city, Guangxi. Since 1977, archaeologists have conducted several investigations into the site. In 2006 and 2016, the Guangxi Institute of Cultural Relics Protection and Archaeology, in collaboration with the Nanning Museum, conducted archaeological excavations and salvage excavations on the site, and discovered relatively rich archaeological and cultural relics. In 2006, more than 50 human burials were excavated and revealed, with burial styles including limb-flexed, contracted, and hyper-flexed (parts of them belong to dismembered burials). The authors apply three-dimensional geometric morphometric methods to the human patellae (n=43) from the site. With three main topics of bilateral asymmetry, sexual dimorphism, and age differentiation, the authors aim to identify and visualize patellae's morphological variation and the intra-group difference in this hunting-gathering society. In addition, the authors form a specific series of three-dimensional geometric morphometric methods on human patellae, including landmark setting, measure error estimation, and functional interpretation. The result indicates that the habitants developed the greater left-biases in the size of the patellae, with the right deflection of both patella apexes. The bilateral asymmetry in size and shape can point to an unbalance locomotion in labor and daily activities. Males are proven to have larger patellae. There is no significant difference in morphology between males and females, while previous research revealed a significant sexual dimorphism in diaphyseal biomechanism. It manifests the asynchronism among biomechanism and morphology, patellae, and diaphyseal limb bones. Subadults tend to own smaller patellae, with longer patellar apexes and steeper patellar bases. Morphological change with age development might refer to the strengthening of the Quadriceps muscle, and the increasing intensity and frequency of knee flexion and extension.

Key words: Guangxi, Prehistory, the Huiyaotian site, Patella, Morphology, Geometric Morphometrics