Is there sexual dimorphism in the presence of Wormian bones? A study of Polish and Lithuanian samples.

Abstract

Background: Wormian bones (WB) originate from accessory ossification centres and occur irregularly within cranial sutures. They are common; however, some authors claim that in some cases WB may reflect developmental instability. Because males are more susceptible to environmental disturbances (which can lead to developmental instability), it is crucial to establish possible discrepancies in WB appearance between sexes. The aim of this study was to examine the sexual differences in the presence of WB.

Materials and methods: 317 adult skeletons from Polish and Lithuanian series: Ostrów Lednicki (185: 135 males and 50 females), Bokštro gatve 6 (69: 42 males and 27 females), and Subačiaus gatve 7 (63: 44 males and 19 females) were selected. The number of WB was noted, and their diameters were measured. In the Lithuanian sample the area of single WB was measured photogrammetrically. Statistical calculations were performed with the significance defined as p < 0.05.

Results: Among the Polish sample 117/135 (86.7%) males and 35/50 (70%) females represented at least one WB. In the Lithuanian sample it was 65/86 (75.6%) and 28/46 (60.9%), respectively. This difference was significant in the Polish (p = 0.009) sample. The sexual difference of WB number was significant (p = 0.01 for the Polish and p = 0.02 for the Lithuanian sample).

Conclusions: Sexual dimorphism of the appearance and number of WB has been confirmed. WB are observed in greater numbers in males, but sexual differences are rarely analysed statistically. There is a need for further work on sexual dimorphism of WB, especially in non-Asian populations.