Familial occurrence of skeletal developmental anomalies as a reflection of biological relationships in a genealogically documented Central European sample (19th to 20th centuries)

Abstract

Skeletal developmental anomalies (SDA) are a subject of constant interest across scientific disciplines, but still mostly as isolates and curiosities. The aim of this study was to find out to what extent the occurrence of SDA reflects documented biological relationships. The skeletal remains of 34 individuals with known genealogical data were available, members of one family over four generations (19th to 20th centuries, Bohemia, Czech Republic), including some inbred individuals. The occurrence of 89 SDA was assessed on the basis of scopic morphological evaluation and X-ray and CT examinations. The degree of similarity between individuals was calculated using a "similarity coefficient" (SC). A linear model was used to test the relationship between positive values of the SC and the relatedness of biologically related individuals. Simultaneously, based on population frequencies of the evaluated anomalies, those that could be considered familial were recorded. A statistically significant relationship between morphological similarity and the biological distance between individuals was found. The greatest similarity was found among close relatives such as parents and children, siblings, or grandparents and grandchildren. The effect of increased consanguinity on the occurrence of anomalies was not confirmed, however. Seventeen SDA shared by closely related individuals were found in the sample, supporting the documented family relationships among them. Eleven of these were selected as possibly familial, but only five were statistically significant: an elongated styloid process, a cervical block vertebrae (arch, facet joints), hamate hamulus aplasia, anteater nose sign, and incomplete fusion of the S1 spinous process. There were also 28 cases of individual occurrences of 17 different SDA, without connection to the documented relationships between individuals.

Does sternal body shape reflect family relationships? A study on a genealogically documented Central European osteological sample (19th–20th centuries)

“…The results showed that there is a significant difference between biologically related and unrelated individuals in sternum shape, and that the shape positively reflects the documented family relationships. In principle, the same findings have in the past been yielded by research on other osteological features, such as non-metric dental and skeletal traits, frontal sinus morphology, or skeletal developmental anomalies (see, e.g., Cvrček et al, 2018Cvrček et al, , 2020Cvrček, Kuželka, et al, 2021a;Paul & Stojanowski, 2017;Stojanowski & Schillaci, 2006). Therefore, it seems possible to use analysis of overall sternum shape for individual identification, whether by comparison of ante-mortem and post-mortem data, or by comparison of biologically related individuals (Macaluso & Lucena, 2014;Verna et al, 2015).…”

“…Additionally, it appears that similarities between individuals can also be sought in the morphology of the ossified xiphoid process, if present and preserved. Thus, this study expands the existing possibilities of sternum analysis for the detection of biological affinity, which has so far been based on specific non-metric traits or developmental anomalies (Creswick et al, 2006;Crubézy, 1992;Cvrček, Kuželka, et al, 2021a). However, it must be taken into account that the sternum is often preserved only in fragments or is completely absent from bioarchaeological materials due to decomposition processes.…”

“…5-7) with different degrees of relatedness. It is part of a genealogically documented collection from the Department of Anthropology of National Museum in Prague (Cvrček et al, 2018(Cvrček et al, , 2020Cvrček, Kuželka, et al, 2021a;Drtikolov a Kaupov a et al, 2021) from the 19th and 20th centuries in which it was possible to find completely preserved sternal bodies in individuals between which there was at least one biological relationship. A measure of biological distance between individuals was obtained by calculating the coefficient of relationship (r).…”

“…It is crucial to find that sternal variation can contribute to the identification of unknown decedents in forensic contexts via the biological profile because of sexual variation in sternum size (Ali et al, 2021; Dorado‐Fernández et al, 2021; Peleg et al, 2020) and to the identification of specific sternal characteristics via the comparison of ante‐mortem and post‐mortem data (Macaluso & Lucena, 2014), for which the high degree of sternal variability is ideal (Weiss et al, 2018). Some studies have pointed to a shared occurrence of some morphological traits among biologically related individuals, such as sternal foramina (Crubézy, 1992), manubriosternal fusion (Cvrček, Kuželka, et al, 2021a), and pectus excavatum (Creswick et al, 2006). This fact could be used both for the detection of biological relationships in individuals from anonymous prehistoric burial grounds (Cockerill et al, 2021; Johnson, 2018; Sjögren et al, 2020) and for the identification of an individual, which would be based on the data of their biological relatives (Palamenghi et al, 2021).…”

“…In this article, we expand on our previous observation of sternal body similarity among potential close biological relatives to investigate sternal body variation using individuals with documented family relationships from the 19th to 20th centuries. Based on the findings of previous studies on the relationship between biological relatedness and skeletal morphological features, such as non-metric osteological and dental traits, frontal sinus morphology or skeletal developmental anomalies (e.g., Case et al, 2017;Cvrček et al, 2018Cvrček et al, , 2020Cvrček, Kuželka, et al, 2021a;Irish et al, 2020;Stojanowski et al, 2018), it can be assumed that the degree of similarity among biological relatives is greater than in unrelated individuals and, conversely, that the degree of variability of the biologically related is lower than that of unrelated individuals. The aim of this study is therefore to describe and analyze the degree of variability of biologically related compared with unrelated individuals based on the shape of their sternal bodies and to answer the following questions: (a) Is there a difference in the shape of the sternal body between biologically close relatives and unrelated individuals?…”