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Sparse Pre-Columbian Human Habitation in Western Amazonia

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Locally extensive pre-Columbian human occupation and modification occurred in the forests of the central and eastern Amazon Basin, but whether comparable impacts extend westward and into the vast terra firme (interfluvial) zones, remains unclear. We analyzed soils from 55 sites across central and western Amazonia to assess the history of human occupation. Sparse occurrences of charcoal and the lack of phytoliths from agricultural and disturbance species in the soils during pre-Columbian times indicated that human impacts on interfluvial forests were small, infrequent, and highly localized. No human artifacts or modified soils were found at any site surveyed. Riverine bluff areas also appeared less heavily occupied and disturbed than similar settings elsewhere. Our data indicate that human impacts on Amazonian forests were heterogeneous across this vast landscape.
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DOI: 10.1126/science.1219982
, 1429 (2012);336 Science
et al.C. H. McMichael
Sparse Pre-Columbian Human Habitation in Western Amazonia
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Acknowledgments: The data reported in this paper are
tabulated in the supplementary materials. This research was
funded by NASA Lunar Science Institute contract NNA09DB33A
(D.A.K.), NASA Cosmochemistry grant NNX11AG78G
(G.R.H.), and NASA Cosmochemistry grant NNX08AH77G
(K.N.). This is Lunar and Planetary Institute contribution
number 1665. We thank the three reviewers for helpful
comments and D. Mittlefehldt, J. Berlin, R. Jones,
and H. McSween for sharing meteorite data sets.
Supplementary Materials
www.sciencemag.org/cgi/content/full/science.1219633/DC1
Materials and Methods
Supplementary Text
Figs. S1 to S21
Tables S1 to S6
References (43132)
25 January 2012; accepted 2 May 2012
Published online 17 May 2012;
10.1126/science.1219633
Sparse Pre-Columbian Human
Habitation in Western Amazonia
C. H. McMichael,
1
* D. R. Piperno,
2
M. B. Bush,
1
M. R. Silman,
3
A. R. Zimmerman,
4
M. F. Raczka,
1
L. C. Lobato
5
Locally extensive pre-Columbian human occupation and modification occurred in the forests of
the central and eastern Amazon Basin, but whether comparable impacts extend westward and into
the vast terra firme (interfluvial) zones, remains unclear. We analyzed soils from 55 sites across
central and western Amazonia to assess the history of human occupation. Sparse occurrences of
charcoal and the lack of phytoliths from agricultural and disturbance species in the soils during
pre-Columbian times indicated that human impacts on interfluvial forests were small, infrequent,
and highly localized. No human artifacts or modified soils were found at any site surveyed.
Riverine bluff areas also appeared less heavily occupied and disturbed than similar settings
elsewhere. Our data indicate that human impacts on Amazonian forests were heterogeneous
across this vast landscape.
T
he Amazon Basin, an area approximately
the size of the continental United States,
is an important reservoir of biodiversity.
A major recent question is the degree to which
humans settled and modified Amazonian land-
scapes before European contact. It was initial-
ly thought that prehistoric Amazonia supported
mainly small and highly mobile human popula-
tions, who exerted little impact on their environ-
ments (1, 2), but recent work has documented
dense and complex human settlements in eastern
Amazonia and on the river bluffs of the central
Amazon. The evidence includes the presence of
highly modified soils such as terra pretas (anthro-
pogenic black earth)(3) and large-scale land-
scape alterations (Fig. 1) (4, 510). The evidence
is impressive, but comes largely from riverine
environments with abundant natural resources,
especially river bluffs, or the driest parts of the
eastern Amazon (Fig. 1).
The extent of this impact on terra firme set-
tings has been uncertain. The terra firme forests
of the interfluvial zone occupy 95% of Amazonia
and have less-fertile soils and poorer-quality
resources (11). Available data from several re-
gions suggest that the prehistoric impacts on in-
terfluvial landscapes were heterogeneous and
highly localized (12, 13). Here we reconstruct
histories of fire, vegetation, and soil modification
from charcoal, phytolith, and geochemical data
recovered from 247 soil cores collected from 55
locations, including sites with known impacts,
across 3,000,000 km
2
in western Amazonia
(Fig. 1 and table S1) (14). We sampled soils
from sites where the probability of past distur-
bances was high, such as river bluffs with known
archaeological hist or i es an d ne ar b y ter ra pretas ,
including T efe, Barcelos, and Iquitos; from a
previously unstudied river bluff at Los Ami-
gos; and from terra firme sites, including Acre,
Iquitos, Tefe, and a transect from Porto Velho
to Manaus (PVM).
Natural fires in Amazonia are rare today
(1517), but fire was a mainstay of prehistoric
land use in the tropics (11, 18, 19). Consequent-
ly, charcoal recovered from soils can provide
evidence of past human disturbances, and phy-
toliths, which document mature and disturbed
vegetation, reflect the intensity of those occupa-
tions. In our samples, charcoal was most com-
mon in soils from riverine bluffs, especially in the
central basin (Fig. 2, C to F). At Barcelos and
Tefe, charcoal was present in many intervals in
most cores, especially from 0 to 40 cm (Fig. 2, D
and F). Charcoal dates ranged from ca. 500 to
2700 calendar years before the present (cal yr
B.P.) at Tefe and from ca. 1200 to 130 0 cal yr B.P.
at Barcelos (table S2). The vegetation at Tefe
appears to have been more heavily affected than
that at Barcelos, which is in agreement with the
1
Department of Biological Sciences, Florida Institute of Tech-
nology, Melbourne, FL 32901, USA.
2
Program in Human Ecology
and Archaeobiology, Department of Anthropology, Smithsonian
National Museum of Natural History, Washington, DC 20560,
USA, and Smithsonian Tropical Research Institute, Balboa,
Panama.
3
Department of Biology, Wake Forest University,
Winston-Salem, NC 27106, USA, and Center for Energy, En-
vironment and Sustainability, Winston-Salem, NC 27106, USA.
4
Department of Geologi cal Sciences, University of Florida,
Williamson Hall, Gainesville, FL 32611, USA.
5
cleo de Ciência e
Tecnologia, Laboratório de Geografia Humana e Planejamento
Ambiental, Universidade Federal de Rondônia, Porto Velho,
Rondônia, Brazil.
*To whom correspondence should be addressed. E-mail:
cmcmicha@my.fit.edu
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longer span of documented occupation. In river-
ine settings, T efe soil phytoliths contained elevated
amounts of early successional herbaceous taxa
(ESH, such as grasses, Heliconia, and sedges)
and som e g r a ss phytoliths that were burned. These
patterns probably reflect forest clearing and other
human disturbances (see phytolith analyses in the
supplementary materials and fig. S1). Howev-
er, neither site yielded crop phytoliths. Arboreal-
dominated phytolith assemblages and relatively
sparse charcoal from riverine Iquitos sites indicate
that the forest remained relatively undisturbed
there, and nutrients and black carbon concentra-
tions in soils from these sites were low. At Los
Amigos, the charcoal dates ranged from 1000 to
4000 cal yr B.P. (table S2), but the soils were not
enriched in nutrients and arboreal taxa domi-
nated phytolith assemblages, which is consistent
with a light and shifting human impact (table S4,
Fig. 2E, and fig. S1).
We recovered little charcoal from soils at
Acre or interfluvial Iquitos sites, indicating a lack
of recurrent or extensive fires over the past sev-
eral thousand years (Fig. 2, A and C, and table S2).
Similar results were obtained from the phytolith
records, which were dominated by forest taxa;
ESH phytoliths were absent or rare (0 to 1%).
No evidence for crops or burned phytoliths was
found (fig. S1). Charcoal was more common in
soils of the PVM transect than in the western in-
terfluvial Iquitos or Acre sites (Fig. 2, A to C).
However, phytolith records showed no signs of
a significant human presence at most sites. ESH
phytoliths were absent or scarce (0 to 6%), and
burned tree phytoliths were nearly absent (Fig.
2B and fig. S1); forest taxa dominated in all
samples. Site 121 contained evidence of maize
cultivation and elevated frequencies of grass and
Heliconia phyoliths, many of which were burned.
No other crops, including squash (Cucurbita spp.),
manioc (Manihot esculenta), arrowroot (Maranta
arundinacea), and leren (Calathea allouia), were
found. Because manioc produces fewer phy-
toliths than many other crops, we cannot state
with the same confidence that it was not grown
nearby.
We found no prehistoric ceramics, stone
tools, or terra pretas in any of the 247 soil cores,
and none of 184 samples analyzed for phytoliths
contained evidence of intensive or persistent forest
clearing. In many soil levels, no ESH phytoliths
were observed in scans of >500 to 1000 addi-
tional phytoliths, underscoring the lack of dis-
turbance that took place in these interfluvial
forests. T ogether, the data suggest that human
population densities in the sampled regions were
low and highly localized, and were not consist-
ent with major population centers with associated
areas of widespread, extensive agriculture (20).
Our data support the idea that humans had much
less impact on interfluvial forests t han on riverine
environments (21) or in the drier eastern forests
(22). However, even regions with known human
sites and terra pretas (such as Barcelos and T efe)
were not subjected to continuous or large-scale
forest clearing or intensive agriculture (Fig. 2),
and show a lesser disturbance signature than found
in modern slash-and-burn systems (see phytolith
analyses in the supplementary materials). Forest
clearings were probably small and short-lived,
and the interior forests were apparently not per-
manently or intensively occupied by humans in
prehistory . We found little indication that repeated
fire, vegetational disturbance, and/or agriculture
extended more than 5 km into the terra firme
forests of the T efe, PVM, Acre, and Iquitos re-
gions (Fig. 2).
Our data imply that the disturbance signature
was stronger in both riverine and interfluvial
forestsofthecentralbasinthaninthewestern
basin (Fig. 2). Even in the PVM transect, how-
ever , evidence for disturbances was patchy and
localized, despite being l ocated 20 to 50 km from
the Madeira River and within 100 to 200 km of
dense concentrations of terra pretas (23) (Fig. 1).
The frequency and distribution of terra pretas doc-
umented along the Madeira River (24)mayhave
continued southward, parallel to our interfluvial
transect. The resulting contrasting pattern of highly
concentrated terra preta soils along the river, with
localized and patchy disturbance 20 to 50 km into
the uplands, illustrates how even in the central
Amazon, intensive landscape modific ation s ap-
pear to be confined to near-riverine locations.
We interpret the charcoal presence along with
low frequencies of burned tree phytoliths, and
the dominance of forest over grass phytoliths, to
mean that fires were mainly confined to the forest
floor . The apparently infrequent and low-intensity
fires do not appear to have penetrated canopies
and altered forest structure substantially at most
sites. Therefore, soil charcoal alone should not
be taken to mean that fires were of sufficient in-
tensity and duration to cause canopy disruption
and major forest alteration [see also (12)].
It is likely that in some forests, edible or other
useful fruit trees were planted or managed, re-
sulting in an enrichment of those species (25).
Palms such as peach palm (Bactris gasipaes)and
Astr ocaryum are economic mainstays in the Am-
azon and are prolific phytolith producers. We
found no evidence for these species in most sam-
ples from every site studied (fig. S1 and palm
distributions in the supplementary materials).
There was no association between palm phytolith
fre qu en c ie s and other evidence of vegetation dis -
turbance, and palm frequencies were never so
high that they implied that a local grove was
present. These data suggest that humans were
not cultivating or selectively managing palms at
most of our study sites. There was also no indi-
cation that many noneconomic species were sel-
ectively removed (26), because little change in
forest composition was seen from the bottom to
the top of the soil cores, including when early suc-
cessional herbaceous taxa and/or charcoal were
present.
Our data imply that the terra firme forests we
studied in the western Amazon Basin were
Fig. 1. Sampled locations within western Amazonia (white squares) in relation to major pre-Columbian
archaeological sites (1, Marajó Island; 2, Santarém; 3, Upper Xingu; 4, Central Amazon Project; 5,
Bolivian Beni), known terra preta locations (brown circles) (3, 32, 33), and soil charcoal survey locations
(black circles) (12, 22). Charcoal and phytolith data are presented from regions outlined in black (B,
Barcelos; T, Tefe; PVM, Porto Velho-Manaus transect; I, Iquitos; Ac, Acre; LA, Los Amigos). The locations of
Rio Madeira and associated terra pretas are shown. Here we define Amazonia as the region drained by the
Amazon River and its tributaries.
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predominantly occupied by relatively small and
shifting human populations during the pre-
Columbian era. This has many implications for
hypotheses about human effects on Amazonian
forests. First, humans may have augmented the
alpha-diversity of some Amazonian landscapes,
but the hyperdiverse floras and faunas are mo re a
product of long-term evolutionary and ecological
processes (27) than anthropic landscape altera-
tion (4, 26, 2830 ). Second, to the extent that
prehistoric deforestation occurred, it was appar-
ently primarily in the eastern Amazon, and this
may have limited the proposed impact of post-
Columbian population collapse and reforestation
on atmospheric CO
2
and CH
4
levels (18, 31).
Third, we canno t assume that Amazonian forests
were resilient in the face of heavy pre-Columbian
disturbance, because vast areas were probably
never heavily disturbed. Prehistoric peoples set-
tled most densely in habitats where resources
were abundant and easily captured, fertile soils
were available, and transportation routes were
nearby, making ecological factors important in
pre-Columbian settlement patterns.
References and Notes
1. B. J. Meggers, Amazonia: Man and Culture in a
Counterfeit Paradise; Worlds of Man: Studies in Cultural
Ecology (Aldine-Atherton, Chicago, 1971).
2. B. J. Meggers, Rev. Archaeol. 25, 31 (2004).
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Amazonian Dark Earths: Origin, Properties, Management
(Kluwer Academic, Dordrecht, Netherlands, 2003).
4. C. L. Erickson, in Time and Complexity in Historical
Ecology, W. Balee, C. L. Erickson, Eds. (Columbia Univ.
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7. E. Neves, J. Petersen, in Time and Complexity in
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Geophysical Archaeology on Marajó Island, Brazil
(Academic Press, San Diego, CA, 1991).
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CA, 1998).
12. C. McMichael et al., Holocene 22, 131 (2012).
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available as supplementary materials on Science Online
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Change, M. B. Bush, J. R. Flenley, Eds. (Springer,
Chichester, UK, 2007), pp. 185212.
20. R. Nevle, D. Bird, W. Ruddiman, R. Dull, Holocene 21,
853 (2011).
21. W. M. Denevan, Ann. Assoc. Am. Geogr. 86, 654 (1996).
22. M. B. Bush, M. R. Silman, C. McMichael, S. Saatchi,
Philos. Trans. R. Soc. London Ser. B 363 , 1795 (2008).
23. M. Heckenberger, E. G. Neves, Annu. Rev. Anthropol. 38,
251 (2009).
24. J. Fraser, A. Junqueira, N. Kawa, C. Moraes, C. Clement,
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9, 33 (2010).
Acknowledgments: Field work and
14
C dating of charcoal
fragments were funded by the NSF Ecology Program
(awards DEB 0742301 and DEB 0743666). Other funding
was provided by the Florida Institute of Technology; the
Smithsonian National Museum of Natural History, including
a Restricted Endowment and Small Grant Award; and the
Smithsonian Tropical Research Institute. All data will be
deposited in the Neotoma Database (www.neotomadb.org/).
We thank B. McMichael, A. Correa-Metrio, J. Hernandez,
T. Harrison, and B. Rado for field assistance.
Supplementary Materials
www.sciencemag.org/cgi/content/full/336/6087/1429/DC1
Materials and Methods
Supplementary Text
Fig. S1
Tables S1 to S4
References (3465)
2 February 2012; accepted 16 April 2012
10.1126/science.1219982
Fig. 2. Regionalmaps,soilcharcoaldistributions,andphytolithpercentagesforsoilcoresfromriverine
(red squares and text) and interfluvial (black squares and text) sites in each region: Acre (A), PVM (B),
Iquitos (C), Tefe (D),LosAmigos(E), and Barcelos (F). Areas of lower (darker) and higher (lighter)
elevations illustrate drainage and rivers (from 90-mresolution data from the Shuttle Radar Topography
Mission) on each regional map. Colored boxes indicatecharcoalresultsforeachcorewithineachsite
(see legend). Sites are listed in a north-to-south orientation. Soil cores with accompanying phytolith
data are denoted with P. Phytolith percentages (column P) are listed to the right of the charcoal results.
Geographic coordinates of all sites are provided in table S3.
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... The locations of soil modifications and earthworks suggest that large and complex societies existed, primarily in seasonal forests and within 15 km of river floodplains (Arroyo-Kalin, 2010;Bush et al., 2015;Denevan, 1996;Woods & Glaser, 2004;Lehmann et al., 2007;Neves & Petersen, 2006;Peripato et al., 2023;Prümers et al., 2022;Watling et al., 2017). But there is less evidence of large-scale human activities in aseasonal terra firme forests (Heijink et al., 2020;McMichael et al., 2012;Piperno et al., 2017Piperno et al., , 2019Piperno et al., , 2021. Fire in Amazonian forests (today and in the past) is mainly associated with human activities as many forests are too wet for natural ignitions to spread (Bush et al., 2008;Cochrane, 2003;Cochrane & Schulze, 1998;Gosling et al., 2021;Malhi et al., 2014). ...
... Our findings suggested that ecological legacies from past human activities are more common near river margins, which is in agreement with previous work from the western and central areas of Amazonia (Bush et al., 2015;Levis et al., 2017;McMichael et al., 2012;Piperno et al., 2021;Zuquim et al., 2023). Beng Tapu is situated within 1 km of the Suriname River, making it easily accessible by boat and abundant in terrestrial and aquatic resources. ...
... This discrepancy may be explained by differences in the density of past populations and settlements, and with that their activities, transient nature and impact on the forests (Piperno et al., 2017;Prümers et al., 2022). Several sites in northwestern Amazonia have also shown no or a small (<1 km) impact due to past human activities (Heijink et al., 2020;McMichael et al., 2012;Piperno et al., 2021), further supporting heterogenous ecological legacies in Amazonia. Therefore, it is important not to extrapolate data across Amazonia, but to expand archaeological and palaeoecological research in data-scarce regions to understand these forests in their historical context. ...
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Disturbances in tropical forests can have long‐lasting ecological impacts, but their manifestations (ecological legacies) in modern forests are uncertain. Many Amazonian forests bear the mark of past soil modifications, species enrichments, and fire events, but the trajectories of ecological legacies from the pre‐contact or post‐colonial period remain relatively unexplored. We assessed the fire and vegetation history from 15 soil cores ranging from 0 to 10 km from a post‐colonial Surinamese archaeological site. We show that (1) fires occurred from 96 bc to recent times and induced significant vegetation change, (2) persistent ecological legacies from pre‐contact and post‐colonial fire and deforestation practices were mainly within 1 km of the archaeological site, and (3) palm enrichment of Attalea, Oenocarpus and Astrocaryum occurred within 0, 1, and 8 km of the archaeological site, respectively. Our results challenge the notion of spatially extensive and persistent ecological legacies. Instead, our data indicate that the persistence and extent of ecological legacies are dependent on their timing, frequency, type, and intensity. Examining the mechanisms and manifestations of ecological legacies is crucial in assessing forest resilience and Indigenous and local land rights in the highly threatened Amazonian forests.
... Amazonia is a continental-sized landscape holding one of the world's great river systems, the largest tropical forest on the globe, and much of the New World's biotic diversity (Fig. 1). The extent to which pre-Columbian human societies occupied and significantly impacted Amazonian environments have been long-standing questions and are currently under active debate (e.g., Meggers, 1971;McMichael et al., 2012a;Clement et al., 2015;Levis et al., 2017;Watling et al., 2017;Piperno et al., 2021;Balée, 2023). There is no longer disagreement that in some regions dense, complex human populations exerted significant, sometimes profound impacts of various kinds on landscapes leaving legacies that are seen today (e.g., mound settlements, raised agricultural fields, roads, geometric earthworks called geoglyphs, highly modified anthropic soils called Amazonian Dark Earths or terra preta) (e.g, Heckenberger et al., 2003;Erickson, 2008;Pärssinen et al., 2009;Arroyo-Kalin, 2010;Denevan, 2011;Neves and Petersen, 1991;Iriarte et al., 2020;Peripato et al., 2023;Schmidt et al., 2023;Rostain et al., 2024). ...
... The terrestrial soil phytolith, charcoal, and soil chemistry evidence has led to views that prehistoric human impacts on the Amazon forest were heterogenous across that huge landscape, from sparse to intensive, with near-river and -tributary areas being more affected than interfluvial contexts (e.g., McMichael et al., 2012a;Piperno et al., 2019Piperno et al., , 2021Heijink et al., 2020Heijink et al., , 2023. Nonetheless, much more work is needed in the terra firme forest along with greater consideration of under-studied post-European influences (e.g., Heijink et al., 2023;McMichael et al., 2023a) and less reliance on modern vegetational characteristics in the absence of direct paleoecological data (see Ǻkesson et al., 2021) before we understand prehistoric impacts on forests and their role in shaping present biodiversity across Amazonia at-large. ...
... Charcoal studies were also carried out on Tapiche-Blanco soils. Iq-N and Los Amigos were previously studied for phytoliths and charcoal (McMichael et al., 2012a;Piperno et al., 2019). Herein, new phytolith analysis was undertaken to better investigate aspects of their records such as palm usage and forest composition change through time. ...
... Radiocarbon dates obtained from the three study sites span from the mid-Holocene to the end of the pre-Columbian period; see Fig 2 and S2 Table. At MC87, five calibrated dates obtained from the pits RH2 (30)(31)(32)(33)(34)(35), C4 (5-10, 10-15) and C5 (10)(11)(12)(13)(14)(15)(35)(36)(37)(38)(39)(40) were spread over a period ranging from 662 to 945 CE. Four dates, obtained from the pits RH1 (0-5, 10-15) and C2 (15- (15)(16)(17)(18)(19)(20)(20)(21)(22)(23)(24)(25) and C17 (10-15) spanned over a period from 430 CE to 976 CE, while dates obtained from C13 (10)(11)(12)(13)(14)(15)(15)(16)(17)(18)(19)(20) and C15 (5-10) spanned over a period from 1296 to 1446 CE At GALB, radiocarbon dating revealed a more complex chronology. ...
... At MC87, five calibrated dates obtained from the pits RH2 (30)(31)(32)(33)(34)(35), C4 (5-10, 10-15) and C5 (10)(11)(12)(13)(14)(15)(35)(36)(37)(38)(39)(40) were spread over a period ranging from 662 to 945 CE. Four dates, obtained from the pits RH1 (0-5, 10-15) and C2 (15- (15)(16)(17)(18)(19)(20)(20)(21)(22)(23)(24)(25) and C17 (10-15) spanned over a period from 430 CE to 976 CE, while dates obtained from C13 (10)(11)(12)(13)(14)(15)(15)(16)(17)(18)(19)(20) and C15 (5-10) spanned over a period from 1296 to 1446 CE At GALB, radiocarbon dating revealed a more complex chronology. One ancient date calibrated at 7739-7588 BCE was obtained from C7 (40)(41)(42)(43)(44)(45). ...
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In the past two decades, repeated discoveries of numerous geometric earthworks in interfluvial regions of Amazonia have shed new light onto the territorial extent and the long-term impact of pre-Columbian populations on contemporary landscapes. In particular, the recent development of LiDAR imagery has accelerated the discovery of earthworks in densely forested hinterlands throughout the Amazon basin and the Guiana Shield. This study aimed to evaluate the extent and landscape-scale spatial variations of pre-Columbian disturbances at three ring ditch sites in the French Guiana hinterland. We carried out extensive soil surveys along approximately 1 km-long transects spanning from ring ditches through the surrounding landscapes, and drawn upon multiple indicators, including archaeological artifacts, macro- and micro-charcoals, soil colorimetry, and physicochemical properties to retrace the pre-Columbian history of these sites in terms of occupation periods, anthropogenic soil alteration, and ancient land use. Our results revealed a perennial occupation of these sites over long periods ranging from the 5th and 15th centuries CE, with local enrichments in chemical indicators (Corg, N, Mg, K, Ca) both within the enclosures of ring ditches and in the surrounding landscapes. Physicochemical properties variations were accompanied by variations in soil colorimetry, with darker soils within the enclosure of ring ditches in terra-firme areas. Interestingly however, soil properties did not meet all the characteristics of the so-called Amazonian Dark Earths, thus advocating a paradigm shift towards a better integration of Amazonian Brown Earths into the definition of anthropogenic soils in Amazonia. Soil disturbances were also associated to local enrichments in macro- and micro-charcoals that support in situ fire management that could be attributed to forest clearance and/or slash-and-burn cultivation. Taken together, our results support the idea that pre-Columbian societies made extensive use of their landscapes in the interfluvial regions of the French Guiana hinterlands.
... Phytoliths, which are silica microfossils produced by many Neotropical plant families [39], can be analyzed from terrestrial soil cores to provide a localized signal (around 10 s to 100 s of meters) of vegetation change [40,41]. Phytoliths and charcoal derived from terrestrial soil cores have been used to indicate local-scale fire events and vegetation change in Amazonian forests over the last 5000 years [39,42]. Phytoliths can be used to detect the cultivation of plants such as maize (Zea mays), gourds, and squashes (Cucurbitaceae), lerén (Calathea allouia), arrowroot (Maranta spp.), rice (Oryza spp.), and bananas (Musa spp., which were cultivated following the arrival of Europeans) [39,[43][44][45]. ...
... There is also the long-term human occupation of the region, and maize has been cultivated in some areas for at least 6000 years [49]. Many areas of northwestern Amazonia, however, contain little to no past human footprints [42]. The influence of past human activity on palm abundance is thus unclear. ...
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The Ecuadorian Amazon holds more biodiversity than most other places on Earth. Palms are a particularly dominant component of the vegetation; however, it remains unknown to what degree the pattern has persisted through time. Here, we investigate the persistence of palm dominance through time and the degree to which past human activities (e.g., fire, cultivation, and forest opening) have affected changes in palm abundances across five regions of the Ecuadorian Amazon. We analyzed soil cores (40–80 cm depth) from each region for charcoal (evidence of past fire) and phytoliths (evidence of past vegetation change). The timings of fires (based on 14C radiocarbon dates), the occurrence, recurrence, and number of fires (based on charcoal presence and abundance in samples), and the amount of change in palm abundances (based on phytoliths) varied within and between the studied regions. The charcoal and phytolith results indicate the presence of low levels of past human activity at all sites. Our results show that patterns of modern palm hyperdominance found in Amazonian forests have not been persistent through time, and that even low levels of past human activities can affect palm abundance.
... Para abordar essas hipóteses, nossa pesquisa buscará aplicar métodos comuns às abordagens geoarqueológica e paleoecológica -especificamente, micromorfologia, geoquímica e granulometria de solos, associadas a análises de fitólitos e isótopos de carbono -para compreender o processo de formação da Terra Preta e da vegetação atual sobre os sítios arqueológicos Terra Preta do Mangabal e do Campo do Jacaré. No seio da discussão feita anteriormente (Capítulo 1) acerca das modificações paisagísticas pelos povos indígenas nas terras baixas amazônicas no Holoceno tardio, compreender como as interações entre pessoas e paisagens ocorreram no alto rio Tapajós, uma das principais conexões entre o vale amazônico e o planalto central brasileiro, nos ajudará a compor o cenário dessas transformações em comparação às pesquisas arqueológicas desenvolvidas nas demais regiões da bacia (e.g.Iriarte et al., 2020;Maezumi et al., 2018;McMichael et al., 2012;Watling et al., 2017). ...
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Este estudo foca em compreender os processos de formação dos solos e das feições vegetais sobre o sítio arqueológico Terra Preta do Mangabal e o Campo do Jacaré, ambos localizados na região do alto rio Tapajós, sudoeste do estado Pará. O contato do primeiro um sítio arqueológico com matriz de Terra Preta com vegetação florestal com o segundo um campo composto por vegetação de gramíneas, sem Terra Preta, com poucas e esparsas evidências arqueológicas ocorrendo em superfície conforma um contato fito-pedológico entre campos de vegetação aberta e áreas florestais comuns na região do alto rio Tapajós. Os métodos utilizados para a investigação da gênese dessa paisagem, advindos da paleoecologia (fitólitos e isótopos estáveis de carbono) e da geoarqueologia (geoquímica e micromorfologia de solos), demonstraram que há fortes indícios de que a ocupação humana em Terra Preta do Mangabal tenha sido a propulsora da formação do Campo do Jacaré.
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Alguns dos grandes debates da arqueologia amazônica passam pela densidade populacional no passado pré-colonial; as diferenças entre as ocupações da várzea e da chamada terra firme; e, finalmente, os impactos que as ocupações tiveram para a composição da Amazônia como conhecemos hoje. Este texto parte do pressuposto de que a Amazônia é um legado do manejo milenar das populações nativas. A oportunidade de fazer arqueologia com os Zo’é e na Terra Indígena Zo’é, uma porção de interflúvio da margem norte do rio Amazonas entre os rios Erepecuru e Cuminapanema, uma das cada vez mais escassas porções de floresta preservada da Amazônia, nos permite acrescentar dados para este debate em uma região praticamente desconhecida do ponto de vista da arqueologia. Com um mapeamento inicial de sítios identificados em expedições guiadas pelos Zo’é e uma classificação inicial que também leva em conta as observações dos Zo’é, afirmaremos que esta porção do interflúvio vem sendo intensamente manejada ao longo dos últimos milênios. E o mais importante, os resultados iniciais mostram que a arqueologia com povos indígenas é uma estratégia interessante para o debate e também para dar destaque à importância das populações nativas para manutenção da Amazônia.
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Amazonian Dark Earths are not only a testament to the vanished civilizations of the Amazon Basin, but may provide the answer to how the large, sophisticated societies were able to sustain intensive agriculture in an environment with mostly infertile soils. Locally known as Terra Preta de Indio or Indian black earth, these anomalous soils are even today fertile and highly productive. Though clearly associated with pre-European settlements questions remain whether the Dark Earths were intentionally produced or merely a by-product of habitation activities. This publication provides a comprehensive review of our current understanding of these fascinating soils: their origin, properties, and management through time. These new and multidisciplinary perspectives by leading experts on Amazonian Dark Earths may pave the way for the next revolution of soil management in the humid tropics.
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The regenerative qualities identified in prehistoric, anthropogenic Amazonian dark earths suggest that notoriously infertile tropical soils can be greatly improved. Soil enhancement practices by ancient Amerindians allowed them to cultivate the land intensively, without needing to continually clear new fields from forest. As increasing populations place ever greater pressure on tropical forests, this legacy of rich, 'living' soils warrants further study in the search for high-yield, land-intensive, yet sustainable forms of management. The international group of contributors to this volume provides a variety of stances centering on aspects of the origin, distribution, variability, persistence, and use of Amazonian dark earths.
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