Did pre-Columbian populations of the Amazonian biome reach carrying capacity during the Late Holocene?

Abstract

The increasingly better-known archaeological record of the Amazon basin, the Orinoco basin, and the Guianas both questions the long-standing premise of a pristine tropical rainforest environment and also provides evidence for major biome-scale cultural and technological transitions prior to European colonisation. Associated changes in pre-Columbian human population size and density, however, are poorly known and often estimated on the basis of unreliable assumptions and guesswork. Drawing on recent developments in the aggregate analysis of large radiocarbon databases, here we present and examine different proxies for relative population change between 1050 BC and AD 1500 within this broad region. By using a robust model-testing approach, our analyses document that the growth of pre-Columbian human population over the 1,700 years prior to European colonisation adheres to a logistic model of demographic growth. This suggests that, at an aggregate level, these pre-Columbian populations had likely reached carrying capacity (however high) before the onset of European colonisation. Our analyses also demonstrate that this aggregate scenario shows considerable variability when projected geographically, which bears on our overall understanding of the resilience of past human food procurement strategies. Lastly, our results provide important insights into pre-Columbian demographic trends and offer novel perspectives on demic expansions, language diversification, and subsistence intensification in the Amazonian biome during the late Holocene.

The origins of Amazonian landscapes: Plant cultivation, domestication and the spread of food production in tropical South America

“…Interestingly, our data indicate that maize either appears or becomes more dominant only after the development of Amazonian anthrosols. The development of ABEs may have allowed for the expansion of the cultivation of this productive crop beyond lake margins, which probably increased the carrying capacity of the land to sustain the large populations observed in the population growth trends using radiocarbon databases (Arroyo-Kalin and Riris, 2020). While maize likely played a supplemental role during its adoption and dispersal during the middle Holocene, it likely became a more important part of the diet with the development of Amazonian anthrosol agriculture.…”

Diversity, multilingualism and inter-ethnic relations in the long-term history of the Upper Rio Negro region of the Amazon

“…The diversity of localized and dispersed examples of such constructions throughout most of the Amazon Basin demonstrates that the socio-political changes at the beginning of the first millennium CE occurred on a large scale. This coincides with the beginning period of population growth that was experienced in the Late Holocene [33]. Apparently, all these changes were not related to any specific ceramic tradition or cultural group, but to a series of long-term interactions.…”

“…Early occupations of the Amazon were made by several kinds of tropical foragers societies, who first produced ceramics before 4000 BCE, a time when horticulture was still nascent in the region [31]. By around 1500 BCE one finds intense production of ceramics, sedentary life, population growth, development of extensive slash-and-burn agriculture and semi-intensive house gardens, which marked a new phase with major cultural changes in the natural landscape of Amazonia [31][32][33]. By 0 CE, there is greater evidence of large sedentary settlements, the construction of mounds, roads, canals, the formation of terras pretas (Amazonian Dark Earths, anthropic dark soils of high fertility produced by long-term occupations), and the construction of geoglyphs and monumental artificial structures in the Amazon River and some of its largest tributaries, such as the Upper Purús, Upper Madeira and Upper Xingú [34].…”

“…The analysis by Arroyo-Kalin & Riris [33] suggests that the Arawakan expansion occurred from the middle Orinoco and the Guianas, going south and west around 300-400 BCE, followed by a period of heterogeneous regional growth, with processes of interregional cross fertilization and formation of small areas of terras pretas between 100-300 CE and 500-600 CE, and population decline in Central Amazonia. This was followed by a period of population growth, associated with the expansion of the Incised-Punctuated and Polychrome traditions, which were likely related to Kariban and Tupian expansions, between 600 and 1200 CE.…”

A genomic perspective on South American human history

“…Some studies suggest that this exponential rate of growth was maintained until the arrival of Europeans, at least in Amazonia (Arroyo-Kalin, 2018), while others indicate a slowdown in growth or even a decrease in population size in some areas, possibly due to having reached carrying capacity, autochthonous diseases, or even climate and social change (Arroyo-Kalin and Riris, 2021;Bush et al, 2021). However, as expected, the majority of genetic and archeological data pointed to the highest mortality rate occurring after Europeans arrived in the Americas, probably peaking later in the colonization period (Browning et al, 2018;Jones et al, 2021;Castro e Silva et al, 2022).…”