Early and Middle Holocene Hunter-Gatherer Occupations in Western Amazonia: The Hidden Shell Middens

Abstract

We report on previously unknown early archaeological sites in the Bolivian lowlands, demonstrating for the first time early and middle Holocene human presence in western Amazonia. Multidisciplinary research in forest islands situated in seasonally-inundated savannahs has revealed stratified shell middens produced by human foragers as early as 10,000 years ago, making them the oldest archaeological sites in the region. The absence of stone resources and partial burial by recent alluvial sediments has meant that these kinds of deposits have, until now, remained unidentified. We conducted core sampling, archaeological excavations and an interdisciplinary study of the stratigraphy and recovered materials from three shell midden mounds. Based on multiple lines of evidence, including radiocarbon dating, sedimentary proxies (elements, steroids and black carbon), micromorphology and faunal analysis, we demonstrate the anthropogenic origin and antiquity of these sites. In a tropical and geomorphologically active landscape often considered challenging both for early human occupation and for the preservation of hunter-gatherer sites, the newly discovered shell middens provide evidence for early to middle Holocene occupation and illustrate the potential for identifying and interpreting early open-air archaeological sites in western Amazonia. The existence of early hunter-gatherer sites in the Bolivian lowlands sheds new light on the region’s past and offers a new context within which the late Holocene “Earthmovers” of the Llanos de Moxos could have emerged.

Emergent Complexity, Changing Landscapes, and Spheres of Interaction in Southeastern South America During the Middle and Late Holocene

“…As in the wetlands of southeastern Uruguay (Iriarte 2013), the Llanos de Moxos in Bolivia (Lombardo et al 2013), and the Paraná Delta (Bonomo et al 2011b), mounds in the Pantanal are easily recognized as forest islands via remote sensing. Occupation of the Pantanal goes back to circa 9200 cal yr BP, as evidenced by a preceramic site located on the terraces of the Paraguay River.…”

“…Interestingly, the purported homeland of the Tupian stock in the southwestern Amazon has one of the longest cultural histories in the entire Amazon. Early Holocene shell middens have recently been discovered in the Llanos de Moxos (Lombardo et al 2013) and the Brazilian Guaporé River (Miller 1992(Miller , 2013, while other evidence includes the presence of 5,000-year-old anthropogenic dark earths, one of the earliest centers of pottery production-dated to around 4,000 cal yr BP Fig. 2 Composite graph showing dates of all archaeological sites, mound and enclosure complexes, and oversized pithouses combined with Araucaria forest and Campos (high-altitude grasslands) pollen curves from Cambará do Sul record (Behling et al 2004).…”

Neotectonics, flooding patterns and landscape evolution in southern Amazonia

“…Likewise, as people lived in the LM since the early Holocene (Lombardo et al, 2013b), it is to be expected that neotectonics had important effects on pre-Columbian peoples too. There is very little data yet about early Holocene human presence in southern Amazonia, the only study published so far (Lombardo et al, 2013b) suggests that hunter-gatherers settled in the southern LM from 10 500 till 4200 cal yr BP, approximately.…”

“…Recent research shows that the LM was first inhabited by hunter-gatherers at the beginning of the Holocene (Lombardo et al, 2013b). Its landscape has since then been significantly changed during the late Holocene by the so-called "Earthmover" societies, who built an extensive array of earthworks (Erickson, 2008;Mann, 2008;Lombardo and Prümers, 2010;Lombardo et al, 2011b).…”

“…Its landscape has since then been significantly changed during the late Holocene by the so-called "Earthmover" societies, who built an extensive array of earthworks (Erickson, 2008;Mann, 2008;Lombardo and Prümers, 2010;Lombardo et al, 2011b). We know very little about the way early hunter-gatherers dealt with the seasonal floods during the early to mid-Holocene, but evidence suggests that they had to abandon the LM around 4000 yr BP (before present) because of a large-scale environmental change, which also caused the burial of the early archaeological sites with fluvial sediments (Lombardo et al, 2013b). Inundation patterns also played an important role in shaping the way in which the late Holocene "Earthmovers" adapted to their local environment and reshaped the landscape, determining the spatial distribution of different earthworks (Lombardo et al, 2011b); especially in order to improve the drainage of agricultural land (Lombardo et al, 2011a(Lombardo et al, , 2012.…”