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Early and middle holocene hunter-gatherer occupations in western Amazonia: the hidden shell middens.

Lombardo U, Szabo K, Capriles JM, May JH, Amelung W, Hutterer R, Lehndorff E, Plotzki A, Veit H - PLoS ONE (2013)

Bottom Line: 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.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.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.

View Article: PubMed Central - PubMed

Affiliation: Institute of Geography, University of Bern, Bern, Switzerland.

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.

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Material retrieved from the uppermost 30 cm of SM1.Unit I, corresponding to the late-Holocene occupation. A) Fragmented pottery; b) Bone tools; c) Fragment of human skull; d) Biogenic burnt earth, probably a wasp chamber.
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pone-0072746-g005: Material retrieved from the uppermost 30 cm of SM1.Unit I, corresponding to the late-Holocene occupation. A) Fragmented pottery; b) Bone tools; c) Fragment of human skull; d) Biogenic burnt earth, probably a wasp chamber.

Mentions: Cores from the three forest islands selected for sampling, two east of Trinidad (SM1, SM3) and one west of the Mamoré River (SM2) (see Fig. 1b), revealed organic-rich, stratified sequences of accumulated deposits of freshwater gastropod shells belonging to the genus Pomacea (Fig. 2). Test excavations at SM1 (Fig. 1c, d) exposed a 1.7 m stratigraphic profile of a midden containing dense accumulations of shells, as well as animal bones and charcoal throughout. The excavation could not go deeper because at 1.7 m we reached the water table. However, a core taken from the bottom of the excavation indicates that the shell midden extended about 80 cm deeper. The base of the midden is found at a depth of about 150 cm below to the current surface of the savannah, where the earliest archaeological materials date to 10604±126 cal BP. The radiocarbon dates generally follow a vertical trajectory, with deeper deposits being older. Assuming an onion-like accretion growth model for SM1 (Fig. 3), the ages between 5000 and 4000 cal BP could indicate a period in which the midden grew in extension rather than in elevation, with each additional mound layer enveloping the last. The radiocarbon chronology and stratigraphic sequence of SM1 (Fig. 3, Table 1) shows two distinct depositional phases: 1) a stratified shell mound (mostly composed of freshwater apple snails, Pomacea spp.) (Fig. 4), which grew upward and outward throughout the early and middle Holocene (Units III–VII), and 2) an overlying layer composed of organic refuse containing pottery, bone tools and human bones (Fig. 5), dated to the late Holocene (Unit I). These are separated by a thin layer rich in pieces of burnt clay and earth with diameters of between 2 cm and 6 cm (Fig. 6a) (Unit II). The base of the shell midden rests on an older surface on which a paleosol has formed abutting the midden but not below it. Radiocarbon ages of the paleosol throughout the region (Table 1, Figure S2) indicate that it formed synchronously with the deposition of the midden. The paleosol and the flanks of the shell mound are covered by 1.5 meters of clayey and silty sediments, resulting from a middle Holocene fluvial deposition of the Grande River [22].The cores from the shell middens SM2 and SM3 show an analogous stratigraphic and chronological structure (Fig. 2).


Early and middle holocene hunter-gatherer occupations in western Amazonia: the hidden shell middens.

Lombardo U, Szabo K, Capriles JM, May JH, Amelung W, Hutterer R, Lehndorff E, Plotzki A, Veit H - PLoS ONE (2013)

Material retrieved from the uppermost 30 cm of SM1.Unit I, corresponding to the late-Holocene occupation. A) Fragmented pottery; b) Bone tools; c) Fragment of human skull; d) Biogenic burnt earth, probably a wasp chamber.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3755986&req=5

pone-0072746-g005: Material retrieved from the uppermost 30 cm of SM1.Unit I, corresponding to the late-Holocene occupation. A) Fragmented pottery; b) Bone tools; c) Fragment of human skull; d) Biogenic burnt earth, probably a wasp chamber.
Mentions: Cores from the three forest islands selected for sampling, two east of Trinidad (SM1, SM3) and one west of the Mamoré River (SM2) (see Fig. 1b), revealed organic-rich, stratified sequences of accumulated deposits of freshwater gastropod shells belonging to the genus Pomacea (Fig. 2). Test excavations at SM1 (Fig. 1c, d) exposed a 1.7 m stratigraphic profile of a midden containing dense accumulations of shells, as well as animal bones and charcoal throughout. The excavation could not go deeper because at 1.7 m we reached the water table. However, a core taken from the bottom of the excavation indicates that the shell midden extended about 80 cm deeper. The base of the midden is found at a depth of about 150 cm below to the current surface of the savannah, where the earliest archaeological materials date to 10604±126 cal BP. The radiocarbon dates generally follow a vertical trajectory, with deeper deposits being older. Assuming an onion-like accretion growth model for SM1 (Fig. 3), the ages between 5000 and 4000 cal BP could indicate a period in which the midden grew in extension rather than in elevation, with each additional mound layer enveloping the last. The radiocarbon chronology and stratigraphic sequence of SM1 (Fig. 3, Table 1) shows two distinct depositional phases: 1) a stratified shell mound (mostly composed of freshwater apple snails, Pomacea spp.) (Fig. 4), which grew upward and outward throughout the early and middle Holocene (Units III–VII), and 2) an overlying layer composed of organic refuse containing pottery, bone tools and human bones (Fig. 5), dated to the late Holocene (Unit I). These are separated by a thin layer rich in pieces of burnt clay and earth with diameters of between 2 cm and 6 cm (Fig. 6a) (Unit II). The base of the shell midden rests on an older surface on which a paleosol has formed abutting the midden but not below it. Radiocarbon ages of the paleosol throughout the region (Table 1, Figure S2) indicate that it formed synchronously with the deposition of the midden. The paleosol and the flanks of the shell mound are covered by 1.5 meters of clayey and silty sediments, resulting from a middle Holocene fluvial deposition of the Grande River [22].The cores from the shell middens SM2 and SM3 show an analogous stratigraphic and chronological structure (Fig. 2).

Bottom Line: 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.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.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.

View Article: PubMed Central - PubMed

Affiliation: Institute of Geography, University of Bern, Bern, Switzerland.

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.

Show MeSH
Related in: MedlinePlus