Seaweed-eating sheep show that δ34 S evidence for marine diets can be fully masked by sea spray effects

Freshwater wetland–driven variation in sulfur isotope compositions: Implications for human paleodiet and ecological research

Sulfur isotope (δ34S) analyses are an important archaeological and ecological tool for understanding human and animal migration and diet, but δ34S can be difficult to interpret, particularly in archaeological human-mobility studies, when measured isotope compositions are strongly 34S-depleted relative to regional baselines. Sulfides, which accumulate under anoxic conditions and have distinctively low δ34S, are potentially key for understanding this but are often overlooked in studies of vertebrate δ34S. We analyze an ecologically wide range of archaeological taxa to build an interpretive framework for understanding the impact of sulfide-influenced δ34S on vertebrate consumers. Results provide the first demonstration that δ34S of higher-level consumers can be heavily impacted by freshwater wetland resource use. This source of δ34S variation is significant because it is linked to a globally distributed habitat and occurs at the bottom of the δ34S spectrum, which, for archaeologists, is primarily used for assessing human mobility. Our findings have significant implications for rethinking traditional interpretive frameworks of human mobility and diet, and for exploring the historical ecology of past freshwater wetland ecosystems. Given the tremendous importance of wetlands’ ecosystem services today, such insights on the structure and human dynamics of past wetlands could be valuable for guiding restoration work.

Pig management in the Neolithic Near East and East Asia clarified with isotope analyses of bulk collagen and amino acids

The chemical analysis of animal bones from ancient sites has become a common approach in archeological research investigating animal utilization and domestication by past humans. Although several chemical indicators have been used to determine pig management practices in ancient societies, one indicator that can clarify human-animal relationships in the early stages of domestication is the change in the animal’s diet from its wild diet, which can be detected using isotope analysis of its bones. Omnivores, such as boars, are assumed to have shared foods with humans as their interaction increased, and a shift in the isotopic (carbon and nitrogen) compositions of their bone collagen toward humans are considered evidence of domestication. This approach has found evidence of early-stage pig management with human leftovers and feces in prehistoric East Asia, including in Neolithic China, Korea and Japan. However, in the Near East, one of the origins of animal domestication, even individual animals considered to be domesticated pigs according to zooarcheological data (such as morphological characteristics and mortality patterns) display isotopic compositions of bulk collagen that differ from those of humans but are close to those of herbivores. This result indicates that these pigs were fed special foods, such as legumes, rather than human leftovers or feces. However, the carbon and nitrogen isotopic compositions of the bulk collagen of herbivores found at the same sites showed huge variations, so the interpretation of the pigs’ diet is consequently unclear. In this study, a compound-specific nitrogen isotope analysis was used to clarify the pig diet and management strategies unique to the Neolithic Near East, Turkey and Syria, together with a carbon and nitrogen isotope analysis of bulk collagen. This study examines the diversity of pig management techniques in early agricultural societies and their relationship with the availability of other domestic animals and farming practices.

Sulfur isotopes as a proxy for human diet and mobility from the preclassic through colonial periods in the Eastern Maya lowlands

Maya archaeologists have long been interested in understanding ancient diets because they provide information about broad-scale economic and societal transformations. Though paleodietary studies have primarily relied on stable carbon (δ13C) and nitrogen (δ15N) isotopic analyses of human bone collagen to document the types of food people consumed, stable sulfur (δ34S) isotope analysis can potentially provide valuable data to identify terrestrial, freshwater, or marine/coastal food sources, as well as determine human mobility and migration patterns. Here we assess applications of δ34S for investigating Maya diet and migration through stable isotope analyses of human bone collagen (δ13C, δ15N, and δ34S) from 114 individuals from 12 sites in the Eastern Maya lowlands, temporally spanning from the Late Preclassic (300 BCE-300 CE) through Colonial periods (1520-1800 CE). Results document a diet dominated by maize and other terrestrial resources, consistent with expectations for this inland region. Because δ34S values reflect local geology, our analyses also identified recent migrants to the Eastern lowlands who had non-local δ34S signatures. When combined with other indicators of mobility (e.g., strontium isotopes), sulfur isotopic data provide a powerful tool to investigate movement across a person's lifespan. This study represents the largest examination of archaeological human δ34S isotope values for the Maya lowlands and provides a foundation for novel insights into both subsistence practices and migration.

Diversity aboard a Tudor warship: investigating the origins of the Mary Rose crew using multi-isotope analysis

The great Tudor warship, the Mary Rose, which sank tragically in the Solent in 1545 AD, presents a rare archaeological opportunity to research individuals for whom the precise timing and nature of death are known. A long-standing question surrounds the composition of the Tudor navy and whether the crew were largely British or had more diverse origins. This study takes a multi-isotope approach, combining strontium (⁸⁷Sr/⁸⁶Sr), oxygen (δ¹⁸O), sulfur (δ³⁴S), carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope analysis of dental samples to reconstruct the childhood diet and origins of eight of the Mary Rose crew. Forensic ancestry estimation was also employed on a subsample. Provenancing isotope data tentatively suggests as many as three of the crew may have originated from warmer, more southerly climates than Britain. Five have isotope values indicative of childhoods spent in western Britain, one of which had cranial morphology suggestive of African ancestry. The general trend of relatively high δ¹⁵N and low δ¹³C values suggests a broadly comparable diet to contemporaneous British and European communities. This multi-isotope approach and the nature of the archaeological context has allowed the reconstruction of the biographies of eight Tudor individuals to a higher resolution than is usually possible.