Stable C & N isotopes in 2100 Year-B.P. human bone collagen indicate rare dietary dominance of C4 plants in NE-Italy

Abstract

C₄ plants (e.g. maize, millet), part of our current diet, are only endemic of reduced areas in South-Europe due to their need of warm climates. Since the first vestiges of agriculture in Europe remains of C₄ plants were recorded but their overall proportion in the human diet remains unknown. Therefore, isotopic (δ¹³C and δ¹⁵N) composition of bone collagen from the skeletal remains (human and animals) of a Celtic population, Cenomani Gauls, from Verona (3^rd to 1^st century BC) in the NE Italy provide a new perspective on this matter. The δ¹³C collagen values of 90 human skeletal individuals range between -20.2‰ and -9.7‰ (V-PDB) with a mean value of -15.3‰. As present day C₄ plants have δ¹³C values around -11‰, which is equivalent to -9.5‰ for samples of preindustrial age, the less negative δ¹³C values in these individuals indicate a diet dominated by C₄ plants. This palaeodietary study indicates that some European populations predominantly consumed cultivated C₄ plants 2100 year B.P. This is supported by the paleobotanical records and ancient Roman sources (e.g. Pliny the Elder), which indicate that millet was a staple food in South-Europe.