Reconstructing Hominin Diets with Stable Isotope Analysis of Amino Acids: New Perspectives and Future Directions

Abstract

Stable isotope analysis of teeth and bones is regularly applied by archeologists and paleoanthropologists seeking to reconstruct diets, ecologies, and environments of past hominin populations. Moving beyond the now prevalent study of stable isotope ratios from bulk materials, researchers are increasingly turning to stable isotope ratios of individual amino acids to obtain more detailed and robust insights into trophic level and resource use. In the present article, we provide a guide on how to best use amino acid stable isotope ratios to determine hominin dietary behaviors and ecologies, past and present. We highlight existing uncertainties of interpretation and the methodological developments required to ensure good practice. In doing so, we hope to make this promising approach more broadly accessible to researchers at a variety of career stages and from a variety of methodological and academic backgrounds who seek to delve into new depths in the study of dietary composition.

Diets, stress, and disease in the Etruscan society: Isotope analysis and infantile skeletal palaeopathology from Pontecagnano (Campania, southern Italy, 730–580 BCE)

“…For example, calcium isotope analysis is an emerging tool in the study of breastfeeding and weaning timing, as calcium isotope values vary depending on breast milk, water, and the variable nature of solid foods introduced in the diet [ 228 ]. Compound-Specific Isotope Analysis (CSIA) of δ 13 C and δ 15 N in bone collagen can provide high-resolution data on the protein contribution of different food types (cereals, terrestrial animals, and marine sources), overcoming some of the dietary equifinality issues that may arise with traditional stable isotope analysis [ 229 ]. Equally important, δ 13 C amino acid and δ 15 N amino acid may better elucidate not only dietary reliance from bulk diet but also the contribution of minor proteins that may be responsible for unexplained δ 13 C and δ 15 N variations [ 78 ], as well as characterize the amino acid profile of maternal milk production [ 199 ].…”

Enhanced dietary reconstruction of Korean prehistoric populations by combining δ13C and δ15N amino acids of bone collagen

“…If humans had a mixed diet, we need to consider each β and TDF value from different food sources. Furthermore, there is a variation in β and TDF values in an ecological niche due to the different primary producers in ecosystems [ 4 ]. For example, the β value of C 3 plants is +8.4‰ and the β value of C 4 plants is -0.4‰ and the β value of marine plants -3.4‰ [ 32 ].…”

“…Moreover, the same plant species at the base of the terrestrial food webs can have a large variability in bulk stable isotope values, owing to the isotopic compositions of their soils of origin and due to possible manuring [ 8 , 9 ]. Thus, bulk isotopic values of each food source in human diets can vary according to local environments and soil conditions [ 4 , 8 , 9 ]. Furthermore, bulk isotope data can be strongly influenced by metabolic parameters such as dietary routing, and consumer-to-diet isotopic offsets [ 10 ].…”

Discovering Nature’s Fingerprints: Isotope Ratio Analysis on Bioanalytical Mass Spectrometers

“…Technical advances to make them measurable in robust and specific ways can have many applications. For amino acids in humans, for example, applications can range from insights into the origins of the early hominins, 68 to biomedical research dissecting human/diet/microbiome interactions 69 and pinpointing aberrations in cancer metabolism. 70 ■ WHAT MAY BECOME POSSIBLE Natural isotope fingerprints require predictions of where to carefully look for informative patterns.…”