Incidence of Intrazygomatic Sutures in Rhesus Macaques

Abstract

Craniofacial sutures are weak points compared to rigid bone on the skull thence they must be shielded from unduly high stresses so as not to disrupt vital growth processes and skeletal functions, especially in areas such as the midface. However, under rare circumstances, extra sutures may present in the midface such as intrazygomatic sutures (incidence of 2.5–6.5% in modern human populations), which arguably would cause unfavorable impact on the ontogeny and biomechanics of the facial skeletons. In this study, the skeletal collection derived from Cayo Santiago (CS) and CS‐derived Rhesus macaque (Macaca mulatta) populations in the Caribbean Primate Research Center was screened for the intrazygomatic sutures. It was hypothesized that the incidence of the intrazygomatic suture in Rhesus macaques was comparable to that in humans. Results demonstrated that, in all examinable skulls with known sex and age information (Total 2483), there are only six specimens that carry intrazygomatic sutures (two Females and four Males; three on left side and three on right side; five with one suture and one with two sutures). Thus, the overall incidence of intrazygomatic sutures in Rhesus macaques, 0.24%, is significantly lower than that in humans (p<0.001). The negative impact of intrazygomatic sutures in the midface needs more biomechanical and morphometric analyses, and insights into this rare condition may deepen our understanding of the craniofacial form and adaptation, and help to improve therapeutic philosophies in corrective and regenerative medicine. Supported by NSF HOMINID BCS‐0725183.