Age of Pelvic Bone Fusion

In general, apes grow more rapidly than humans and reach sexual maturity faster. The prolongation of growth in humans is reflected in delayed schedules of ossification and fusion of elements in the human skeleton, and accordingly later ages for the attainment of skeletal maturity in humans than in apes. However, skeletal development is not uniformly delayed in humans: important differences exist in the patterns of bone growth and fusion of skeletal elements between apes and humans. One feature in which humans appear to be unique is in our prolonged growth of the pelvis after the age of sexual maturity. Both the total superoinferior length and mediolateral breadth of the pelvis continues to grow markedly after puberty, and do not reach adult proportions until the late teens years (growth in the pelvis of males may continue until 21 of age, and females may complete pelvic growth even later). This prolongation of growth is accomplished by relatively late fusion of the separate centers of ossification that form the bones of the pelvis. It has been suggested that ape-human differences in pelvic shape (see Pelvic Height and Iliac Flare) are brought about in part by these differences in the time of bony fusion of the pelvic elements. Alternatively, human pelvic growth may simply reflect the relatively late (in developmental terms) acceleration of growth in body size (the adolescent growth spurt) and life history differences between apes and humans. A link between patterns of pelvic growth and human life history is supported by the finding that, cross-culturally, variation in maturation rates of female pelves are correlated with variation in ages of menarchy and first reproduction.