On paleoepidemiology of spina bifida sacralis: prevalence of the anomaly in Late Scythians of lower Dnieper region

Abstract

Spina bifida is a developmental anomaly that is thought to be caused by a combination of hereditary and en-vironmental factors. Though the most significant association was found with the folic acid deficit during early em-bryogenesis, numerous genetic variants were also found to be in some association with the development of neu-ral tube defects, but this data is inconsistent. It is still debated whether the unremarkable anomaly (spina bifida occulta) often observed in osteological samples is truly a form of neural tube defects forming in early embryo-genesis, or is a minor variation that is forming later in postnatal life. Also, data is equivocal regarding the neuro-logical consequences of sacral spina bifida occulta, some pointing to its clinical significance, others stating that it does not affect the wellbeing in any way. Though paleopathological studies on spina bifida are numerous, the frequency of the anomaly remains largely unknown for the Early Iron Age population of the Eurasian steppes. This study examines presence of sacral spina bifida in a Late Scynthian sample (3rd c. BC — 3rd с. AD) from the northern Black Sea region. Totally, 89 skeletons were examined, originating from cemeteries near Nikolayevka and Zolotaya Balka villages (Kherson Oblast, Ukrain). These cemeteries are located along the Dnieper river bank about 90 km apart. The people they represent were settled agriculturalists. The defect was scored when either or all of the three upper sacral vertebrae were affected (S1–S3), its level was recorded. Totally, 16 % of individuals were affected. The majority of defects were observed solely on S1 level. Only two cases of spina bifida sacralis totalis were recorded. The frequency of the anomaly was not significantly different either between males and fe-males, or between younger (<35 years) and older (>35 years) adults. In two instances, two individuals buried in a common grave both had spina bifida sacralis which may point to a biological relationship between them. The fre-quency of spina bifida sacralis is very close to the mean values, reported in the literature. Thus, no evidence of an increased selection against individuals in this group with this form of skeletal anomaly, or a significant impact of envi-ronmental factors, leading to its development in ontogenesis, is present. Also, contrary to literature data, it seems that in this sample age and sex were not the factors significantly contributing to the trait’s variation, though the age dynamics of this trait needs further consideration using a sample with higher proportion of senile individuals.