Heredity of sutural patterns at the pterion in rhesus monkeys

Abstract

Five bones of the cranial vault articulate on the lateral aspect of the skull near the pterion. The pattern of articulation in these sutures varies among and within primate species and has been used as a criterion in taxonomic studies, and in archeological and forensic studies of skeletal variability. The sutural patterns have remarkable consistency within species, which leads to the hypothesis that these patterns have a genetic basis. We investigated variations in the pterion in 422 skulls of 66 rhesus monkey families from the long-standing colony on Cayo Santiago Island. Four types of articulation patterns were recorded: (1) the Tempo-Frontal type (TF), (2) the Spheno-Parietal type (SP), (3) the X type, and (4) the Zygomatico-Temporal type (ZT). The results demonstrated that the TF type is the most common suture pattern in rhesus monkeys, comparable to some other anthropoid species, but not humans and some apes. The SP type accounts for 14% of the whole sample and is concentrated in a dozen families. Mothers with the SP phenotype have a high incidence of offspring with SP phenotypes. Most non-SP mothers having SP offspring often have siblings or family members from previous generations having the SP type. These findings suggest that variations of sutural patterns are regulated by specific genes. The SP type is likely controlled by an autosomal recessive gene. This is the first time that variation in the sutural patterns at the pterion have been investigated in pedigree trees, and the inheritance patterns of the variation defined, such that genes which control these variations can begin to be identified with DNA sequencing. Supported by NSF Physical Anthropology grant BCS 0240865.