Amazing media response to our latest paper in PloS ONE

Our paper “Early and Middle Holocene Hunter-Gatherer Occupations in Western Amazonia: The Hidden Shell Middens” has been published less that 3 days ago in PLoS ONE. It was included in the press release of PLoS ONE and, once the embargo expired, we produced two other press releases (see previous post).

I am amazed by the interest that media from all around the world have shown! Till now I have counted more than 50 articles from USA, Spain, Germany, Brazil, Bolivia, Russia, Australia etc. Plus, several people posted about our research in their blogs.

Samples from the internet press of the last 2 days:

Germany:

http://www.welt.de/wissenschaft/umwelt/article119476408/Dieser-Huegel-verraet-fruehe-Menschen-am-Amazonas.html

http://www.spiegel.de/wissenschaft/mensch/spuren-steinzeitlicher-besiedlung-im-amazonasgebiet-a-919159.html

Australia:
http://theconversation.com/hidden-in-middens-new-clues-of-earliest-known-bolivian-amazon-humans-17583

http://www.dailytelegraph.com.au/news/breaking-news/poo-signature-leads-to-archaeological-find/story-fni0xqi3-1226706175551
http://www.sbs.com.au/news/article/2013/08/28/poo-signature-leads-archaeological-find

Brazil:

http://oglobo.globo.com/ciencia/humanos-habitavam-amazonia-antes-do-que-se-pensava-9740162

Bolivia:
http://www.eldeber.com.bo/beni-era-seco-hace-10000-anos/130904180837

http://www.la-razon.com/la_revista/Hallan-vestigios-humanos-anos-Beni_0_1897610235.html
http://latino.foxnews.com/latino/lifestyle/2013/09/03/archaeologists-find-evidence-10400-year-old-human-presence-in-bolivia/

Spain:
http://www.nationalgeographic.com.es/articulo/historia/actualidad/8586/los_llanos_moxos_sus_misteriosos_conchales.html#

http://www.europapress.es/ciencia/noticia-ser-humano-ya-habitaba-amazonia-boliviana-hace-10000-anos-20130829102354.html

http://www.agenciasinc.es/Noticias/La-misteriosa-isla-del-Tesoro-de-la-Amazonia-boliviana-guarda-la-basura-de-sus-primeros-habitantes
http://www.antena3.com/especiales/noticias/ciencia/hazte-eco/noticias/ser-humano-habito-amazonas-hace-10000-anos_2013082900228.html

UK:

http://www.dailymail.co.uk/sciencetech/article-2404383/10-000-year-old-remains-settlements-unearthed-Bolivia--making-oldest-archaeological-site-Amazon.html?ITO=1490&ns_mchannel=rss&ns_campaign=1490#comments

USA:

http://www.nbcnews.com/science/humans-explored-treasure-island-much-earlier-thought-8C11027554

http://news.yahoo.com/humans-landed-treasure-island-earlier-thought-211618124.html

http://www.huffingtonpost.com/2013/08/30/ancient-humans-amazon-earlier-trash-heaps_n_3842690.html

http://www.huffingtonpost.com/2013/08/30/10000-year-old-bolivian-settlements-amazon_n_3844189.html

A blog post I liked:

http://thenaturalhistorian.com/2013/08/30/amazonian-forest-islands-accidental-products-of-ancient-human-occupation/

The Hidden Shell Middens - Press releases

Here two media releases, one in English written by Kat and the another in Spanish written by José, about our latest paper "Early and Middle Holocene Hunter-Gatherer Occupations in Western Amazonia: The Hidden Shell Middens" published in PLoS ONE the 28th of August 2013.

Traces of the earliest inhabitants of Bolivian Amazonia hidden in plain sight

The enigmatic ‘forest islands’ set amidst the grasslands of Bolivian Amazonia have yielded the earliest evidence of human habitation in the region.   Previously thought to be relict landforms cut away by shifting rivers, or long-term bird rookeries or termite mounds, these piles of freshwater snails, animal bones and charcoal are now known to have been built up over millennia, starting from at least 10,400 years ago, by ancient hunter-gatherers. 

Using novel approaches drawn from archaeology, geomorphology and geochemistry, an international team of researchers, led by Dr. Umberto Lombardo of the University of Bern, has conducted detailed excavations of a large mound known locally as Isla del Tesoro (Treasure Island).  Distinctive chemical signatures of human presence were recorded at high levels throughout the mound sediments, and studies of the animal bones and shells indicate they are the remains of ancient human meals.  Isla del Tesoro tells us that from over 10,000 years ago, hunter-gatherers were moving across the grasslands hunting a variety of mammals, catching fish and birds, and gathering large quantities of freshwater snails.

 Over time, the refuse of these hunting and gathering forays built up forming mounds which sat elevated above the floodplain.  These refuse or ‘midden’ mounds in turn provided a habitat for local plants and animals, transforming them into the forest islands so recognisable in the landscape today.  It is highly likely that many more midden mounds lie buried beneath the metres of silts under the current savannah.

Regularly flooded savannah landscapes such as those surrounding Isla del Tesoro have long been thought to be an inhospitable environment for early hunter gatherers.   The densities of animal prey are lower and less predictable than in coastal areas, near stable watercourses or in forested areas where early South American archaeological sites are typically found.  Lombardo and colleagues’ work at Isla de Tesoro tells us that early South Americans moved across a wider variety of landscapes than previously thought, and adapted their ways of life to cope in these challenging environments.

Paper details

Lombardo, Umberto¹, Katherine Szabó², Jose M. Capriles³, Jan-Hendrik May², Wulf Amelung⁴, Rainer Hutterer⁵, Eva Lehndorff⁴, Anna Plotzki¹, Heinz Veit¹. 2013.  Early and middle Holocene hunter-gatherer occupations in Western Amazonia: the hidden shell middens. PLOS ONE.  Online from 28^th August, 5.00pm (EDT)

¹ University of Bern, Switzerland

² University of Wollongong, Australia

³ University of Pittsburgh, USA

⁴ University of Bonn, Germany

⁵ Alexander Koenig Zoological Museum, Bonn, Germany

Conchales ocultos revelan milenaria presencia humana en la Amazonia boliviana

Un equipo internacional de investigadores, dirigido por el Dr. Umberto Lombardo, de la Universidad de Berna – Suiza y que incluye al arqueólogo boliviano, Dr. José M. Capriles, acaba de publicar en la revista científica de acceso abierto PLoS ONE, un estudio que documenta la existencia de asentamientos humanos en la Amazonía boliviana desde al menos 10.400 años atrás. En esta región se atribuía la ausencia de ocupaciones pre-agrícolas a condiciones ambientales desfavorables. Sin embargo, esta investigación multidisciplinaria combinó información de arqueología, geomorfología y geoquímica, para identificar restos de asentamientos de cazadores-recolectores en “islas de bosque” o “islas de monte” en los Llanos de Moxos del Departamento del Beni. Los autores de la investigación informan que tres de estas islas son conchales o montículos formados por conchas (además de huesos, tierra quemada y carbón) desechados por grupos de cazadores-recolectores móviles. Análisis de radiocarbono indican que estos grupos se establecieron en la región a principios del Holoceno, es decir, hace aproximadamente 10.400 años y que mantuvieron su modo de subsistencia varios milenos. Las islas de bosque estudiadas parecen haber sido abandonadas hace aproximadamente 4000 años atrás para luego ser reocupadas poco antes de la conquista española por las sociedades agrícolas que construyeron las lomas y camellones del Beni. Esta investigación permite confirmar que la Amazonía boliviana estuvo poblada por seres humanos mucho más antes de lo imaginado y que sus pobladores fueron agentes activos en la formación del paisaje.

Referencia

Umberto Lombardo, Katherine Szabo, José M. Capriles, Jan-Hendrik May, Wulf Amelung, Rainer Hutterer, Eva Lehndorff, Anna Plotzki & Heinz Veit. 2013. Early and Middle Holocene Hunter-Gatherer Occupations in Western Amazonia: The Hidden Shell Middens. PLoS ONE Vol. 8, No. 8, pp. 1-14. E72746.

http://www.plosone.org/article/info:doi/10.1371/journal.pone.0072746

Esta publicación es resultado del “Proyecto de Investigación Arqueológica: Ocupación Humana, Paisajes Antrópicos y Cambio Medioambiental durante el Holoceno en los Llanos de Moxos – Amazonía Boliviana” que cuenta con el apoyo del Viceministerio de Interculturalidad del Estado Plurinacional de Bolivia, la Gobernación del Departamento del Beni, la Fundación Nacional de Ciencias Suiza y otras institucionales internacionales y nacionales.

Trinidad 2013?

The Llanos de Moxos, in the Bolivian Amazon, are a fascinating site. Full of archaeological remains, striking and diverse tropical fauna and flora and many indigenous cultures. The Llanos covers about 150.000 km² of seasonally flooded savannah. For many years it has been largely neglected by the scientific community, only a handful of researchers have worked in the area. Fortunately, things are now beginning to change. In the last half a decade several new researchers (including myself) have decided to study this fascinating region. As far as I know, there are now several ongoing research projects in the LM. I list here those that come to mind:

Us, thePaleoGeoEcology group from University of Bern.

John Walker, who has recently set up a very interesting blog about the BolivianAmazon.

Heiko Prümers’ group, who have been doing  archaeological research and excavations in theregion for over a decade

Clark Erickson, who has been working in the LM since the seventies.

Francis Mayle’s group, who are producing the first pollen archives from the LM’s lakes

José Iriarte’s group, who are using phytoliths to study pre-Columbian agriculture.

The ORE-HYBAMproject of the IRD, who have published several papers on the Hydrology of theLM.

Rolf Aalto,who studies the sedimentation processes along the Beni and Mamoré rivers

Victoria Reyes-García’s group of anthropologists working with the Chimanes

Eduardo Machicado, who is doing his PhD at Cambridge, focusing on the area of SanIgnacio de Moxos

A few weeks ago, whilst reading a post on John Walker’s blog, I thought it would be great if we could all meet next summer in Trinidad,Beni. Actually, Last year I already talked about organising some kind of meeting among the ‘Moxos researchers’ with Marcos Michel, currently Director of la Direccion General de Patrimonio Cultural of the Bolivian Government, and with other people from the Governación del Beni, and all seemed very keen with the idea. It would be great to share some of our work and experiences among ourselves, but also among local researchers and interested parties. There are plenty of Benianos who are passionate about the  past of the LM and some areperforming their own research (such as Ricardo Bottega in Trinidad or Jaime Bocchetti in Santa Ana de Yacuma). It could be really interesting to engage in an exchange of ideas and experiences between “cientificos gringos” and Bolivianos!

If you like the idea and want to get involved you could do 2 things: 1) if you know of other ongoing projects in the Llanos de Moxos you could send the link of this page to those involved and send me their names (so that I can add them to the list). 2) Let me know when would be the best time for you to have the meeting in Trinidad, considering that it would have to be during the dry season (June-October). Keep in mind that there is a conference on Amazonian archaeology in Ecuador from the 7 to 14 of September, so we should avoid overlapping. Although I am not entirely sure if the conference has been confirmed.

Cheers, and I hope to see you in Trinidad next summer!

Umberto

People and environment in pre-Columbian Amazonia: two new proxies

What was the extent of human occupation and environmental impact in the pre-Columbian Amazonia?

This question has been at the center of much of the research on pre-Columbian Amazonia since Betty Meggers published her paper ‘Environmental Limitation on the Development of Culture’ (1). The reconstruction of the Amazon’s past is based on evidence obtained from the study of the present landscape, sediments and archaeological remains. These ‘evidences’ are called proxies. Pollen is a proxy for past vegetation, tree rings are proxies for past climate variability, CO2 stored in the ice cores is a proxy for past levels of atmospheric CO2 and so on.

Paleo-ecologists, geographers, archaeologists etc. trying to understand the region’s past have first to look for proxies (this means going to the field and taking samples of lacustrine sediments and/or soils, or going into the mountains after morains and other glacial deposits); then they have to interpret the data gathered and assess their significance (to what extent does this data represent a local or regional event?): we can say that past values of CO2 inferred from ice cores are proxies for past global concentrations of CO2 because the atmosphere is well mixed, but we cannot say that the extent of a moraine in a particular valley indicates past global temperature or precipitations, because local conditions in that valley could have been (and very likely were) different from the conditions of a similar valley in the other hemisphere. As the process involves different stages, datasets and interpretations, it is not uncommon for researchers to disagree on the conclusions. This has often been the case with regards to Amazonia.

In this post, I will try to provide a brief overview of the proxies (and their interpretations and significance) that have been used to infer the extent of the impact pre-Columbian populations had on Amazonia and the contribution of a recent paper published in Science (2) to our understanding of the region’s past.

The first proxies

When Betty Meggers wrote ‘Environmental Limitation on the Development of Culture’ in the fifties (1), there was not much data on Amazonia. At that time scientists relied considerably on anthropological studies of modern indigenous communities and on written documentation left by the first explorers. The fact that the ‘modern’ indigenous population in Amazonia was limited to small nomadic and semi-nomadic groups was attributed to environmental constraints: unfertile soils and frequent floods. As Amazonian soils cannot support large and stable populations in modern times, it was thought that, also in the past, Amazonia was inhabited by small groups of hunters and gatherers. In contrast, written reports from the first explorers described large and rich societies with plenty of food and gold. Myths such as El Dorado arose on the basis of these reports. However, as the written reports contained some statements that were clearly false, such as the existence of blond women warriors with only one breast (the “Amazonas” from whom the river and the region took their names), these historical documents were often disregarded and the consensus within the scientific community was that Amazonia in the past only hosted small nomadic groups that did not have a significant impact on the environment. 

The discovery of the “lost cities”

In the last 30 years, when more funding, interest and technology became available to spur archaeological research, scholars started to find new evidence of pre-Columbian complex societies in those very places where Megger’s model of environmental determinism predicted that they shouldn’t be. The discovery of raised fields and monumental mounds in the Bolivian Amazon (3,4), the geometric ditches in the Acre (5), the terra preta sites, the earthworks in the upper Xingù (6), the mounds in the Marajo islands, were far more reliable proxies than ‘modern indigenous communities’ and ‘old written reports’. More importantly, these discoveries suggested that Betty Meggers’ model was wrong. Archaeologists (actually, in most cases, North American Anthropologists) started speculating about the significance of these discoveries and how they challenged the theory of environmental determinism. Archaeological evidence showed that environmental constrains did not limited cultural evolution in Amazonia because human intelligence overcame them. People built highly productive raised fields that were able to produce tons of Maize per hectare on a continuous basis (without fallow periods); people transformed infertile oxisols in extremely rich terra preta allowing the production of food surpluses that permitted the rise of large and complex societies all over Amazonia. Pre-Columbian Amazonia was now seen by many as a “cultural parkland” (6) and an “anthropogenic cornucopia” (7). Pre-Columbians practiced agroforestry to such an extent that they contributed to the modern patterns of Amazonian biodiversity. Some geographers, paleoecologists and climatologists speculated about the large impact that pre-Columbians had on world climate: As Amazonia was densely populated, then it was also extensively de-forested. Following the discovery of the Americas in 1492, 95% of the original population died because of the spread of the diseases brought by the Europeans. The sharp decrease in population meant the abandonment of the agricultural fields and the re-growth of the rainforest. The forest absorbed huge amounts of CO2 from the atmosphere and, because of this, contributed to trigger the Little Ice Age…

The latest paradigm shift

The above reconstructions, although exciting, have been considered too extreme by some scholars, including myself (4,8); because there is insufficient paleoecological data or archaeological evidence to support them. The main problems with the reconstructions of pre-Columbian Amazonia as an “anthropogenic cornucopia” are related to the interpretation and significance of the proxies taken into account. Although it is a fact that there are thousand of hectares of raised fields in the Bolivian Amazon (the proxy) it is not clear how they were used and how productive they were (the interpretation). Moreover, there is no basis for assuming that similar levels of landscape modification took place elsewhere in Amazonia (the significance or scope). The same is true for other proxies. For instance, terra preta. On what basis do we interpret terra preta as an improved agricultural soil? We all agree that within the Amazon basin there is evidence of past complex society, but can we extrapolate from a few sites to the whole of Amazonia? Till now, the most important argument against the “anthropogenic cornucopia” theory has been the lack of data supporting it. As Betty Meggers said, it is all about wishful thinking. But, a few days ago, a new paper by McMichael et al. (2) added two new proxies to the debate: charcoal and phytoliths. They are actually not new at all, but, for the first time, extensive parts of the Amazonian rain forest have been sampled for the presence of these two proxies. Charcoal is a proxy for fire and phytoliths are a proxy similar to pollen, phytoliths tell us which kinds of plants were cultivated (if any). Both of them have local significance because you can find them only in the very place were the fire or the plants were. But, as McMichael et al. sampled many spots in the Amazon rain forest (247 soil cores collected from 55 locations) , their results are now of regional significance. This is the first time that we have a dataset obtained from the random sampling of an extensive part of Amazonia, rather than mere generalizations of data obtained from small and selected archaeological sites. Based on the analysis of charcoal and phytoliths, McMichael et al. concluded that most of Amazonia was “predominantly occupied by relatively small and shifting human populations during the pre-Columbian era”. This opens up a great and fascinating perspective for future studies. If, as Meggers said more than half a century ago, environment matters: what are the environmental opportunities that allowed the rise of complex societies in some sites such as the Llanos de Moxos in the Bolivian Amazon?

There is still much to be learnt about human-environment interactions in pre-Columbian Amazonia. The Llanos de Moxos, with its great amount, diversity and spatial variability of earthworks, is a promising site for future research.

1) B. J. Meggers (1954). Environmental Limitation on the Development of Culture American Anthropologist  
2) McMichael CH, Piperno DR, Bush MB, Silman MR, Zimmerman AR, Raczka MF, & Lobato LC (2012). Sparse pre-Columbian human habitation in western Amazonia. Science (New York, N.Y.), 336 (6087), 1429-31 PMID: 22700926  
3) Lombardo, U., Prümers, H. (2010). Pre-Columbian human occupation patterns in the eastern plains of the Llanos de Moxos, Bolivian Amazonia Journal of Archaeological Science, 37 (8), 1875-1885  
4) Lombardo, U., Canal-Beeby, E., Fehr, S. and Veit (2011). Raised fields in the Bolivian Amazonia: a prehistoric green revolution or a flood risk mitigation strategy? Journal of Archaeological Science, 38 (3) 5) Pärssinen, M., Schaan, D., and Ranzi (2009). Pre-Columbian geometric earthworks in the upper Purús: a complex society in western Amazonia Antiquity, 83  
6) Heckenberger MJ, Kuikuro A, Kuikuro UT, Russell JC, Schmidt M, Fausto C, & Franchetto B (2003). Amazonia 1492: pristine forest or cultural parkland? Science (New York, N.Y.), 301 (5640), 1710-4 PMID: 14500979  
7) Erickson, C. L (2008). Amazonia: the historical ecology of a domesticated landscape in Handbook of South American archaeology, edited by H. Silverman and W. H. Isbell  
8) Lombardo, U., May, J-H. and Veit, H. (2012). Mid- to late Holocene fluvial activity behind pre-Columbian social complexity in the south-western Amazon basin The Holocene

A story of people and rivers in the Amazon of 5000 years ago

This time I will tell you about a story that began in the Mid-Holocene (5000 years ago) and is set in the Bolivian Amazon. More precisely in the south-eastern part of the Llanos de Moxos seasonally flooded savannah, in what we call the Monumental Mounds Region MMR (Fig. 1).  Here, between 400 and 1400 AD, pre-Columbians built hundreds of monumental earth mounds, known locally as “lomas”. These earth mounds are planned, complex buildings made by one or more pyramids built on top of elevated platforms (Fig. 3-3).  Monumental mounds can be up to 20 meters high and can cover up to 30 hectares. In the MMR there are more than 350 of these pre-Columbian buildings.

Figure 1 The Llanos de Moxos, the MMR (yellow
box) and the paleo-courses of Río Grande (pink lines). 

During the early Holocene (between 11.000 and 5.000 years ago) this portion of Amazonia was relatively dryer than today, inundations were less frequent and rivers transported few sediments. During these stable climatic conditions there was no deposition of fluvial sediments in the savannahs and soils were forming all over the Llanos de Moxos. 

Mid- Holocene: Río Grande built the landscape

But things changed a lot during the Mid-Holocene, between 5 and 4Ky BP. The Rio Grande (pink lines in Fig. 1) entered in a period of frequent avulsions and high sedimentation, probably triggered by a climate change towards wetter conditions. As a result, in the South-eastern LM, it formed a ­fluvial distributary system (FDS) (Fig. 2-1). Suddenly, the landscape was transformed into a large swamp, dominated by something similar to an interior delta. This FDS deposited several levees, crating relief at a local scale (Fig. 2-2), and a sedimentary lobe, creating relief at a regional scale (Fig. 2-3). The former soils were buried and the landscape became a mosaic of patches of savannahs closely interwoven and sometimes enclosed by forested paleo-levees.

Late Holocene: pre-Columbians transformed the landscape

In the MMR, the lobe deposition favoured the development of a complex pre-Columbian society by increasing the region’s agricultural potential. Firstly, it created a convex-up topography, which greatly reduced its susceptibility to ­flooding; secondly, the construction of the elevated ­fluvial levees significantly improved drainage conditions at the local scale. Furthermore, the Río Grande also provided relatively younger sediments derived from its Andean catchment that are rich in nutrients. Thus, the Río Grande removed the two biggest obstacles faced by tropical agriculture in the rest of Amazonia: severe waterlogging and poor soils. But the Río Grande’s job was not perfect: fl­uvial levees enclosed patches of ­floodplain, resulting in ponding and pronounced waterlogging. Thus pre-Columbian people had to transform the landscape through the construction of a drainage system in order to further improve agricultural conditions (Fig. 3-1).

The network of canals had a significant impact on the edaphology of the MMR: it pushed the forest-savannah boundary towards the savannah, eventually increasing the area of well-drained, usable land. The inhabitants of the MMR were very lucky because they also had several lakes placed on the top of the sedimentary lobe. Building canals that transported the water from the lakes to the agricultural fields (Fig. 4), they were able to perform agriculture even during the dry season.

The spatial overlap (Fig. 3-2) between the monumental mounds and the area of deposition of the sedimentary lobe created by the Río Grande during the mid- to late Holocene  suggests that good edaphic conditions favoured the emergence of the monumental mounds culture (Fig. 3-3).

The ­fluvial landscape created by Río Grande was probably an important factor behind the emergence of the monumental mounds culture in the South-eastern LM, as it provided favourable environmental preconditions in terms of soils, nutrients and drainage characteristics. Pre-Columbians additionally modified and improved their environment by building a network of drainage canals.

Figure 4 (a) Drainage canal (A–B) and irrigation canal (C–D) 

built along topographic slopes. (b)The C–D canal in detail;

 the irrigation canal linking Lake San José to the Cotoca mound 

joins pre-existing natural channels. Coring in the middle of 

the canal shows that the bed of the canal is only 50cm below 

the present bed (which is about 50 cm below the modern savannah). 

Therefore, this canal was at most 1 meter deep but went through a slope 

of 3 meters. The only possible function of such a canal was irrigation.

You can find more on this story in my latest paper published on-line in the journal “The Holocene”. It is entitled “Mid- to late-Holocene fluvial activity behind pre-Columbian social complexity in the southwestern Amazon basin” and can be found here. 

Lombardo, U., & Prümers, H. (2010). Pre-Columbian human occupation patterns in the eastern plains of the Llanos de Moxos, Bolivian Amazonia Journal of Archaeological Science, 37 (8), 1875-1885 DOI: 10.1016/j.jas.2010.02.011


Umberto Lombardo, Jan-Hendrik May, & Heinz Veit (2012). Mid- to late-Holocene fluvial activity behind pre-Columbian social complexity in the southwestern Amazon basin The Holocene

Pre-Columbian cherry picking by the New York Times

A few weeks ago, the NYT published an article about pre-Columbian Amazonia. The journalist reported the discovery of pre-Columbian geometric ditches in the Brazilian Acre. These were actually discovered a decade ago and were already described in a book edited by Pärsinnen et al (2003) and again by Pärsinnen et al (2009) in Antiquity, who called them “geoglyphs”. Till today, no one knows what those ditches were excavated for. As Pärsinnen et al. (2009) say: “The function, or functions, of the geoglyphs remain a mystery”. However, the author of the NYT article says that this discovery shows that Amazonia was densely populated in pre-Columbian times and is “potentially upending the conventional understanding of the world’s largest tropical rain forest”.

But, how can we draw conclusions about how pre-Columbian Amazonia looked like on the basis of something that we don't even know what it is?

I can already hear the answer of those who are pushing for the idea of a densely populated Amazonia: it is not only the geoglyphs! What about the terra preta? And the high productive agriculture of the raised fields? And the complex societies of the upper Xingú?

Well, all these archaeological features have one thing in common: they are found in sites that cover a very small and often peripheral part of Amazonia. But, let’s explore these arguments one by one.

Terra preta:

Terra preta is an organic anthrosol that is found in small patches (normally less than 2 hectares) distributed on the bluffs of large Amazonian rivers. Terra preta indicates the presence of pre-Columbian settlements. But it does not say how many people were living there at any given time or how complex those groups of people were from a social point of view. Many publications put together terra preta and terra mulata under the same label of Amazonian Dark Earth (ADE) and then speculate about large areas of high productive soils. But Terra preta properties cannot be extended to terra mulata (which, for example, has far less phosphorous compared with terra preta and lacks the pottery). As I have already discussed here and here, the claims about terra preta being the product of intentional transformation of soil for high productive agriculture have no scientific basis. Glaser and Birck (in press), who are among the greatest experts of the geochemical properties of terra preta, say in their latest paper “there is no scientific evidence indicating that forgotten agricultural techniques for large scale soil fertility improvement are responsible for terra preta genesis.”

Raised fields:

The high productivity of raised field agriculture in South America has never been demonstrated. I wrote a paper about this last year (Lombardo et al. 2011) were it is shown that raised fields in the Bolivian Amazon (which is, by far, the place with the highest amount of raised fields in Amazonia) were built to avoid water logging during periods of extreme precipitations. They were not a pre-Columbian green revolution but a means to adapt and survive in an unfriendly environment.

The Upper Xingú (Heckenberger, 2003):

In the upper Xingú, as Meggers (2003) puts it, the “clear evidence” of complex and large societies is anything but clear: “Heckenberger et al. state that domestic remains cover about 50 to 60% of the ditched areas and would represent 10 to 24 houses with 12 to 16 occupants each, but provide no archaeological evidence for these estimates.”[...] “Heckenberger et al. assert that “Xinguano cultivation and land management…provides a viable alternative” to modern clear-cutting strategies, but they do not describe them.” […] “Even if Heckenberger et al.'s analysis were acceptable, it would have no bearing on the controversy over the pre-Columbian existence of dense settlements and complex social organization in Amazonia. Like other regions with ditches, causeways, and mounds (the Llanos de Moxos, Bolivia; Acre and Marajó, Brazil; and the western Llanos, Venezuela), the Upper Xingu is environmentally and geographically peripheral to the rainforest. “

This last quote is probably the most important. In fact, even if we consider all the archaeological sites as evidence of pre-Columbian complex societies, they are all located in the peripheral regions of Amazonia or along the river floodplains called varzea, the belt of seasonally flooded areas that flanks the Amazonian rivers. Varzea accounts for only the 2% of the Amazon Basin. The problems of extrapolating from these few sites to the whole Amazonia have been extensively discussed by Bush and Silman (2007) and more recently by McMichael et al (2011) and Barlow et al (2011). Based on lake sediments and charcoal distribution analyses, these researchers conclude that human disturbance in Pre-Columbian Amazonia was localized. As Mark Bush, from the Florida Institute of Technology, clearly states: “It is very unlikely that the majority of Amazonia was strongly impacted by human activity.” (PDF of his talk here). In the words of Barlow et al. (2011): “We therefore urge caution before presuming that findings from a few well studied regions can be extrapolated to the entire Amazon, and reject the idea that the pristine myth has been thoroughly debunked by archeological evidence. Instead, we suggest that the influence of historical peoples occurred along gradients, with high impacts in settlements and small and scattered Amazonian Dark Earths, moderate impacts where enrichment planting occurred or where forests were affected by anthropogenic wildfires, and finally a largely imperceptible footprint from subsistence hunting and resource extraction across vast tracts of Amazonian forests that are far from permanent settlements and navigable rivers ”.

How is it possible that the NYT’s journalist, while writing his piece, didn’t bump into any of these papers?

William Woods, a geographer at the University of Kansas, is quoted by the NYT saying: “If one wants to recreate pre-Columbian Amazonia, most of the forest needs to be removed, with many people and a managed, highly productive landscape replacing it”. But, I think that before the scientific community accepts the idea that Amazonia was a highly productive anthropogenic landscape we need far more evidence than rectangular ditches in the Acre and patches of anthrosol.

Post scriptum

All this has important implications for our understanding of the resilience of Amazon ecosystems and the scale of deforestation in pre-Columbian Amazonia. Understanding how resilient Amazon ecosystems are can help inform present and future development and conservation policies for the region. If, as some authors suggest, there was considerable human disturbance in pre-Columbian Amazonia, then we can conclude that Amazonia is highly resilient and that the current degradation of its ecosystems may be reversible. On the other hand, if this resilience is overestimated, then mistaken policies can lead to irreversible loss of biodiversity and ecosystem services (Bush and Silman, 2007). Understanding the extent of pre-Columbian human disturbance of Amazonia is a prerequisite in order to assess the possible influence that post-contact re-forestation had on global climate. It has been estimated that pre-Columbian population in Amazonia fell by 95% after the spread of diseases that followed the arrival of the Spaniards. This sharp fall in population would have meant that large areas under cultivation before the conquest were abandoned and re-colonized by the rainforest. As Amazonia is one of the largest terrestrial players in the global carbon cycle, it has been suggested that the reforestation that followed the conquest could have sequestrated enough CO2 from the atmosphere to become an important factor in triggering the Little Ice Age. More on this here.

References

-Bush, M. B., and Silman, M. R., 2007, Amazonian exploitation revisited: ecological asymmetry and the      policy pendulum: Frontiers in Ecology and the Environment, v. 5, no. 9, p. 457-465.
-Glaser, B., and Birk, J. J., In Press, State of the scientific knowledge on properties and genesis of     Anthropogenic Dark Earths in Central Amazonia (terra preta de Índio): Geochimica et Cosmochimica Acta.
-Heckenberger, M. J., Kuikuro, A., Kuikuro, U. T., Russell, J. C., Schmidt, M., Fausto, C., and Franchetto, B., 2003, Amazonia 1492: pristine forest or cultural parkland?: Science, v. 301, p. 1710-1714.
-Lombardo, U., Canal-Beeby, E., Fehr, S., and Veit, H., 2011, Raised fields in the Bolivian Amazonia: a prehistoric green revolution or a flood risk mitigation strategy?: Journal of Archaeological Science, v. 38, no. 3, p. 502-512.
-Meggers, B. J., 2003, Revisiting Amazonia Circa 1492: Science, v. 302, p. 2067.
-Pärssinen, M., Schaan, D., and Ranzi, A., 2009, Pre-Columbian geometric earthworks in the upper Purús: a complex society in western Amazonia: Antiquity, v. 83, p. 1084-1095.

-McMichael, C., Bush, M., Piperno, D., Silman, M., Zimmerman, A., & Anderson, C. (2011). Spatial and temporal scales of pre-Columbian disturbance associated with western Amazonian lakes The Holocene, 22 (2), 131-141 DOI: 10.1177/0959683611414932
-Barlow, J., Gardner, T., Lees, A., Parry, L., & Peres, C. (2011). How pristine are tropical forests? An ecological perspective on the pre-Columbian human footprint in Amazonia and implications for contemporary conservation Biological Conservation DOI: 10.1016/j.biocon.2011.10.013

Special Issue: Environmental changes and pre-Columbian human influence in the Amazon region

The last number of Geographica Helvetica is a special issue about Amazonia entitled “Environmental changes and pre-Columbian human influence in the Amazon region”. Among the authors there are two prominent pollen specialists, Behling, H. and Mayle, F.E.; the phytogeographer Langstroth, R.; and several members (and ex members) of the paleo-geoecological group at Bern University, including myself. Abstracts can be accessed here.

Our paper, co-authored by Canal-Beeby, E. and Veit, H., is entitled “Eco-archaeological regions in the Bolivian Amazon. An overview of pre-Columbian earthworks linking them to their environmental settings”.

The discovery of extensive pre-Columbian earthworks in north-eastern Bolivia has been seen as evidence that Amazonia was once densely populated by complex societies. This has led some scholars to believe that culture evolved in Amazonia regardless of environmental constraints. However, this view does not take the diversity of earthworks and geo-ecological regions into account, nor their uneven distribution. This paper offers an initial explanation of the possible links that exist between the different types of earthworks in north-eastern Bolivia and their environmental settings and identifies six distinct eco-archaeological regions. Results show a spatial overlap between those areas with greater evidence of past complex societies and areas where environmental constraints were fewer. This suggests that local hydrology and soils influenced the development of pre-Columbian societies in the region.

Lombardo, U., Canal-Beeby, E., & Veit, H. (2011). Eco-archaeological regions in the Bolivian Amazon. An overview of pre-Columbian earthworks linking them to their environmental settings Geographyca Helvetica, 66 (3), 173-182

The extent of human disturbance in pre-Columbian Amazonia

Understanding the extent to which pre-Columbian peoples altered and deforested the Amazon basin is key in order to assess i) the impact that pre-Columbians had on global climate during the Holocene [Dull et al., 2010] and ii) the resilience of the Amazon rainforest to human disturbance [Bush and Silman, 2007]. The first point is essential to our understanding of the major drivers behind climate fluctuations during the Holocene, and hence to help predict future fluctuations. The second point is important to inform conservation and development policies in Amazonia. Unfortunately, the scarcity of archaeological and paleoecological data from the Amazon Basin has favoured the proliferation of “reconstructions of the past” that are hard to test.  Some of these theories have reached broad audiences thanks to the echo provided by popular media and books [Mann, 2005]. New archaeological findings that suggest the existence of complex societies in pre-Columbian Amazonia have led some researchers to define the Amazon Basin as a “manufactured landscape” or an “anthropogenic cornucopia” [Balée and Erickson, 2006; Erickson, 2008].  There are 3 different lines of research that can help assess whether or not these reconstructions are accurate. One is to focus on those regions that host important archaeological remains and study the evidence of complex societies. This work is already being carried out by some archaeologists such as Heiko Prümers. The second area of research is to examine if and how the development of complex societies in the region were influenced by local environmental constraints and opportunities. This is the kind of work that I am carrying out in the Llanos de Moxos and  hope to discuss in another post quite soon J (briefly introduced here…). Another area of research that can help us understand the Amazon’s past is to test if the level of human disturbance associated with the sites where evidence of complex societies has been discovered can be extrapolated to the rest of the Amazon basin.  A milestone paper that looks at the latter, and that has been often cited in this blog, is Bush and Silman (2007).

A few weeks ago, The Holocene published on-line a new paper that delves deep into this question, providing interesting new data [McMichael et al., 2011].  McMichael et al. test the hypothesis that human disturbance was widespread in the Amazon Basin during pre-Columbian times (as some authors have suggested). If this hypothesis is true and the disturbance was widespread then, the authors argue, the sites where permanent settlements were likely to have established should show sedimentary evidence of that disturbance. Hence, they cored lakes (considered by the authors as preferred settlement sites) and sampled soils in the vicinity of the lakes and looked at charcoal and phytoliths. They found that charcoal record was discontinuous and localized. They then concluded, based on the sedimentary evidence: “Our data suggest that while all of the settings examined were occupied or used, the halo of influence around each was limited. It should not be assumed that intensive landscape transformations by prehistoric human populations occurred throughout Amazonia or that Amazonian forests were resilient in the face of heavy historical disturbance”. The paper suggests that pre-Columbians developed into complex societies and substantially altered their environment in those areas where environmental conditions were favourable. They predict that these sites can be found along the main rivers and in those parts of the Amazon Basin that are characterized by a strong seasonality (like the Llanos de Moxos).

In my opinion this paper is a beautiful piece of Science and I invite you to read it!

References:

Balée, W., and C. L. Erickson (2006), Time, complexity and historical ecology, in Time and complexity in historical ecology: studies in the neotropical lowlands, edited by W. Balée and C. L. Erickson, pp. 1-17, Columbia University Press, New York.

Bush, M. B., and M. R. Silman (2007), Amazonian exploitation revisited: ecological asymmetry and the policy pendulum, Frontiers in Ecology and the Environment, 5(9), 457-465.

Dull, R. A., R. J. Nevle, W. I. Woods, D. K. Bird, S. Avnery, and W. M. Denevan (2010), The Columbian Encounter and the Little Ice Age: Abrupt Land Use Change, Fire, and Greenhouse Forcing, Annals of the Association of American Geographers, 100(4), 755-771.

Erickson, C. L. (2008), Amazonia: the historical ecology of a domesticated landscape, in Handbook of South American archaeology, edited by H. Silverman and W. H. Isbell, pp. 157-183, Springer, Berlin.

Mann, C. C. (2005), 1491 New revelations of the Americans before Columbus, Vintage books, New York.

C. H. McMichael, M. B. Bush, D. R. Piperno, M. R. Silman, A. R. Zimmerman, & C. Anderson (2011). Spatial and temporal scales of pre-Columbian disturbance associated with western Amazonian lakes The Holocene : 10.1177/0959683611414932