AUTHOR=Guiry Eric J. , Orchard Trevor J. , Needs-Howarth Suzanne , Szpak Paul TITLE=Freshwater wetland–driven variation in sulfur isotope compositions: Implications for human paleodiet and ecological research JOURNAL=Frontiers in Ecology and Evolution VOLUME=10 YEAR=2022 URL=https://www.frontiersin.org/journals/ecology-and-evolution/articles/10.3389/fevo.2022.953042 DOI=10.3389/fevo.2022.953042 ISSN=2296-701X ABSTRACT=

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.