The enigmatic relationship between epiphyseal fusion and bone development in primates

Abstract

Epiphyseal fusion in primates is a process that occurs in a regular sequence spanning a period of years and thus provides biological anthropologists with a useful marker of maturity that can be used to assess age and stage of development. Despite the many studies that have catalogued fusion timing and sequence pattern, comparatively little research has been devoted to understanding why these sequences exist in the first place. Answering this question is not necessarily intuitive; indeed, given that neither taxonomic affinities nor recent adaptations have been clearly defined, it is a challenge to explain this process in evolutionary terms. In all mammals, there is a tendency for the fusion of epiphyses at joints to occur close in sequence, and this has been proposed to relate to locomotor adaptations. Further consideration of the evidence suggests that linking locomotor behavior to sequence data alone is difficult to prove and may require a different type of evidence. Epiphyseal fusion should be considered in the context of other parameters that affect the developing skeleton, including how joint morphology relates to growth in length, as well as other possible morphological constraints. In recent years, developmental biology has been providing a better understanding of the molecular regulators of epiphyseal fusion. At some point in the near future, we may be able to link our understanding of the genetics of fusion timing to the possible selective mechanisms that are responsible for these sequences.

Inventory and Assessment of the Pongo (Linnaeus, 1760) Skeletal Collection Housed at the Yale Peabody Museum

“…The Yale Peabody Museum sample comprises immature and young adult individuals, providing important specimens for future analyses of orangutan ontogeny and skeletal growth. We recommend further analyses using methods such as permanent crown perikymata counting and radiographic analyses to more accurately assess dental age and add to the available dataset for young orangutans (Beynon et al 1991; Smith 2016; Brimacombe 2017; O'Hara 2017; Stull et al 2021).…”

“…The Yale Peabody Museum sample comprises immature and young adult individuals, providing important specimens for future analyses of orangutan ontogeny and skeletal growth. We recommend further analyses using methods such as permanent crown perikymata counting and radiographic analyses to more accurately assess dental age and add to the available dataset for young orangutans (Beynon et al 1991;Smith 2016;Brimacombe 2017;O'Hara 2017;Stull et al 2021). Four of the orangutans in the collection have associated medical records, and for two individuals (YPM MAM 000345 and YPM MAM 000346), we have detailed birth and death records, providing new reference points for captive-born Pongo abelii developmental (Smith et al 2012;Skinner and Skinner 2017).…”