Chemical analysis of pottery reveals the transition from a maritime to a plant-based economy in pre-colonial coastal Brazil (original) (raw)

2023, Scientific Reports

Understanding long-term dynamics of past socio-ecological systems is essential for their future management. The southern Atlantic Forest coast of Brazil with its biodiverse littoral zone and artisanal fishing communities, is a priority for conservation. Traditional maritime knowledge is thought to have a deep-history and indeed, marine exploitation can be traced back to the middle Holocene. As part of one of South America's largest diasporas, Guarani groups reached the southern Brazilian coast at around 1000 years ago. Their impact on the long-standing coastal economy is unknown, due to poor preservation of organic remains. Through the first organic residue study on Guarani pottery, we show that maize rather than aquatic foods was the most dominant product in pottery at this time. By developing a mixing model based on carbon isotope values of saturated and mono-unsaturated fatty acids we propose new criteria for the identification of maize, opening up avenues for future research. Our data confirms the importance of maize to the pre-colonial Guarani, even in a highly productive coastal environment. The Guarani occupation of this region marks a significant departure from previous socioeconomic systems, potentially leading to loss of traditional knowledge and alleviating anthropogenic pressure, albeit temporarily, on the marine environment. The Atlantic Forest coast of Brazil is one of South America's most productive aquatic ecotones. It is a biodiversity hotspot and a global priority region for biological conservation and restoration 1. Today, marine ecosystem services provide food and livelihood for thousands of people along the Brazilian coastline, notably to rural communities that for a long time relied on a combination of small-scale fishing and plant cultivation as part of their local ecological knowledge. Such indigenous knowledge plays a fundamental role in modern sustainable resource use and biological conservation and is critical to the food security of riverine and coastal fisheries in Brazil 2. The deep historical roots of indigenous knowledge, and its increasing value in conservation and development agendas, require a good understanding of the origin, changing nature and modern legacy of indigenous knowledge and practices. Charting changes in marine resource exploitation throughout the occupation history of this region therefore provides an opportunity to document the heritage of Brazil's Atlantic fisheries, and to