Biological relationships and frontal sinus similarity in skeletal remains with known genealogical data

Abstract

Frontal sinus analysis has potential utility for detecting biologically related individuals. However, the methodological approach to its evaluation, as well as its informative value, have been questioned. The aim of this work is to introduce a new approach to evaluating the frontal sinus using the ‘external supraorbital line’ (ESOL) and to determine whether there are sex differences within families in frontal sinus measurements and whether frontal sinus similarity reflects known genetic relationships in both measurements and morphology. We examined the skeletal remains of 41 adult individuals (25 males, 16 females), all members of one family over four generations (19th to 20th centuries), including individuals with very close consanguinity. CT images of skulls were acquired, and both the dimensions and morphology of the frontal sinuses were analyzed using their portions above the ESOL. No significant sex differences were found within families based on frontal sinus dimensions. Significant relationships were found between biological distance and the maximum height and morphology of the frontal sinuses. The greatest degree of similarity was found among closely related individuals. Additionally, in several cases, there was a greater degree of similarity between first cousins or grandparents and their grandchildren than among siblings or parents and their children. Total surface, volume and width are not significant indicators of relatedness. Known genetic relationships are also supported by individual morphological features. Variability within families with very close consanguineous relationships was lower than within families with common degrees of consanguinity, although differences are significant only for some variables.

Frontal sinus anatomy of the noble Swéerts‐Sporck family and verification of their biological relationships using similarity analysis

“…Virtual surface models of their sinuses were segmented from the CT scans in Morphome3cs software (http://www.morphome3cs.com), (e.g., Musilová, Dupej, Velemínská, Chaumoitre, & Brůžek, 2016), and further processed in Meshlab (Visual Computing Lab, Italian National Research Council), Avizo 7.1 (Visualization Sciences Group, SAS) and Geomagic Studio 2012 (3D Systems, Inc.) in order to obtain water‐tight virtual surface models of the frontal sinuses. The models were cut along a plane that passes through the upper external orbital margins and is parallel to the Frankfurt plane (Borovanský, 1936; Nussen, 2007), this limit being defined by the external supraorbital line (“ESOL”), (Cvrček et al, 2020). A portion superior to this plane was further examined (Figure 2).…”

“…The mesh was cut along this plane in Avizo 7.1. This is a modification of the supraorbital line (SOL; e.g., Nikolova, Toneva, Georgiev, & Lazarov, 2018); we propose its use especially for historical osteological material where the orbital roof is poorly preserved (Cvrček et al, 2020).…”

“…Initially, whether there is a pattern in the metric dimensions related to the sex of the individuals was assessed (Cvrček et al, 2020). Sex classification was performed in Morphome3cs software using fitting support vector machines on the combinations of the total surface area and volume and the maximum height and width of the frontal sinuses.…”

“…It is however possible to identify biological affinity between individuals, although frontal sinuses cannot be used to identify exact relationships (Cameriere et al, 2008). Furthermore, there may be cases of a high degree of coincidental similarity even between biologically related individuals, which must be taken into account (Cvrček et al, 2020).…”

“…Significant differences in frontal sinus size have been found between males and females from different populations (Akhlaghi, Bakhtavar, Moarefdoost, Kamali, & Rafeifar, 2016; Čechová et al, 2019; Choi, Duailibi‐Neto, Beaini, da Silva, & Chilvarquer, 2018). In a genealogically documented sample from the 19th to 20th centuries with a predominance of biologically related individuals, however, there were no such differences between adult males and females (Cvrček et al, 2020). Given this, a significant positive relationship was found between biological relatedness and the degree of similarity of individuals based on the frontal sinus total height and morphology, which matches the findings of previous studies (Kjær et al, 2012; Szilvássy et al, 1987).…”