Microstructural Evidence for Early Childhood Stress in a Community in Transition at Hisban, Jordan

Identification of stress across infancy and childhood can reflect maternal and environmental influences on early life health. In the 19th century community of Hisban, many infants died before 2 years of age with evidence of metabolic disease, including rickets, that likely ties with maternal health. Here the patterns and timing of accentuated lines (AL) in enamel and interglobular dentin (IGD) in dentin in older children, adolescents, and adults from this community are assessed within the mother-infant nexus framework to highlight factors contributing to surviving past infancy. We likewise critically examine IGD as a reflection of early life stress, including nutritional or non-nutritional rickets.

Histological analysis of 29 first and second permanent molars representing 23 non-infant individuals identified the presence and age of IGD formation. Extreme care was taken to identify developmental IGD and remove these observations from analysis. A subsample of six teeth was also observed for AL formation. Ages of IGD and AL formation followed established methods.

Most non-adults (65.2%) had at least one episode of IGD formation, and while all six individuals analyzed for AS and IGD had AL, only one had no evidence of IGD. AL developed at ages much earlier than IGD, although both indicate that the individuals who survived infancy also faced multiple stressors during early life.

The ages of IGD and AL development would indicate that these individuals grappled with multiple causes of physiological stress, but not concurrently. Many biocultural factors could have caused these stressors, primarily mother-infant interactions.