Isotopic Values of Prenatal Development: δ¹³C and δ¹⁵N Variation in Early-Formed Human Tissues

Area of Science:

• Paleoanthropology
• Bioarchaeology
• Isotope Geochemistry

Background:

• Carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope analysis of skeletal tissues offers insights into past diets and physiology.
• Interpreting these isotopes is challenging due to developmental processes and tissue-specific collagen formation in early life.

Purpose of the Study:

• To investigate systematic isotopic offsets in carbon and nitrogen between auditory ossicles, deciduous dentin, long bones, and ribs.
• To assess the implications of these offsets for reconstructing maternal diet and early-life physiology in perinates, neonates, and young infants.

Main Methods:

• Analysis of collagen δ¹³C and δ¹⁵N from 106 samples across 27 individuals.
• Samples were sourced from five archaeological sites spanning the Early/Late Iron Age, Early Roman, and 17th-19th centuries.

Main Results:

• Consistent δ¹⁵N trends showed increases from ossicles to teeth and decreases from teeth to long bone/rib.
• Significant δ¹⁵N offsets were observed between teeth and long bone/rib across all age groups.
• δ¹³C exhibited a systematic increase from ossicle to tooth, with ossicles showing significantly lower values than teeth and long bones/ribs.

Conclusions:

• Isotopic variation in perinates, neonates, and young infants is primarily driven by developmental physiology and tissue turnover, not diet.
• Auditory ossicles reflect mid-prenatal physiology, deciduous dentin reflects late gestation/perinatal periods, and long bones/ribs integrate broader intervals.
• Tissue-specific sampling and reporting are crucial for accurate inferences regarding maternal diet, fetal physiology, and early-life stress.