Paleodietary reconstruction of endemic rodents from the precolumbian Dominican Republic: Discriminating wild feeding behavior from diets linked to human niche construction activities

In the Greater Antilles, certain animal taxa that have long been theorized to have been managed by indigenous peoples prior to AD1492, the main candidates being a group of endemic caviomorph rodents known as hutias (Capromyinae). This isotopic study investigates the paleodiets of several species of endemic rodents from three late precolonial sites in the northern Dominican Republic: El Flaco (cal. ad 990–1452), El Carril (cal. ad 1030–1262), and La Entrada (cal. ad 840–900) to assess whether human influence over animal diets can be determined. We examined bone collagen carbon (δ¹³C_co) and nitrogen (δ¹⁵N) and tooth enamel carbon (δ¹³C_en) isotope values of three species of hutias, Isolobodon portoricensis, Isolobodon montanus, and Plagiodontia aedium, alongside edible rat (Brotomys sp.), and domestic guinea pig (Cavia porcellus). To estimate dietary source contributions, we employed a Bayesian dietary mixing model (FRUITS v.3.0) and ran three different permutations to assess the relative contributions of C₃ or C₄/CAM plants. The addition of an extra 79 wild C₃ and 40 wild C₄/CAM plant species' isotope values from published sources to an established isotopic foodweb for the Caribbean region enabled us to discriminate between wild and domestic C₃ and C₄/CAM plant food sources in two of these models. Our results provide evidence of the significant consumption of domestic C₄/CAM plants by some animals. This likely represents maize (Zea mays) consumption, which is known to have been ubiquitously cultivated by indigenous peoples in the region. This is particularly the case for I. portoricensis, as FRUITS modeling suggests that a few individuals consumed C₄/CAM plants well beyond their expected natural diets as determined from feeding studies of extant hutia species. This may indicate human influence over endemic rodent diets due to niche construction activities such as horticultural practices and may reflect either opportunistic feeding on human produce or the purposeful supplementation of hutia diets by humans.