Evidence of stress in primary incisors of Peruvian children from Chancay culture

Abstract

The study aimed to determine the width of the neonatal line (NNL) and time of occurrence of accentuated lines (ALs) in enamel of deciduous incisors to assess the biological condition during pre, peri- and early postnatal development of individuals from the cemetery. For 32 incisors (16 i¹, 7 i², 9 i₂) thin sections for microscopy analyses were performed. ALs could be identified in the enamel of 14 specimens (43.75%). In the prenatal enamel the earliest observed AL occurred around 69.2 days before birth (upper confidence limit 95% 73.8 days; lower confidence limit 95% 64.7 days), while the latest AL approximately 24.6 days before birth (upper 95% 27.4 days, lower 95% 21.8 days). In postnatal enamel the earliest AL were observed approximately 9 days after birth. Statistical analyses shows that neither prenatal nor postnatal ALs time of occurrence vary with the child’s age at death (Z=-0.168; p = 0.093 for prenatal and Z = 0.048; p = 0.962 for postnatal enamel). The mean value of NNL width was 18 μm (min. 9 μm, max. 36 μm) and no relationship between the child’s age-at-death and neonatal line width (r = 0.117; p = 0.581) was statistically significant. The number of accentuated lines did not significantly affect the individual’s life expectancy (Z = 0.116; p = 0.908) either. The group of children from Cerro Colorado site is characterized by a high frequency and earlier time of occurrence of accentuated lines as well as a greater width of the neonatal line compared to other prehistoric and historical populations. It may indicate worse living conditions and poor biological conditions of the studied Chancay population.