"People have shaped most of terrestrial nature for at least 12,000 years". Really?

This week, Ellis et al. published an important paper in PNAS (https://www.pnas.org/content/118/17/e2023483118). Their main message is that people have shaped most of terrestrial nature for at least 12,000 years. The paper comes with several maps that show how, already 12,000 years ago, places like the Amazon were mostly "Cultured anthromes" with only small parts of it classified as "Wildlands". These are defined as follows: "Wildlands are characterized by the complete absence of human populations and intensive land uses. Cultured anthromes are less than 20% covered by intensive land uses".

You can explore the maps here https://anthroecology.org/anthromes/12kdggv1/maps/ge/

One week before the paper was published, I was sent an embargoed version by a journalist working for an important scientific magazine to comment on the paper. However, none of my comments made it to the final version of the journalist's article. So I decided to post here the questions I was asked and my answers.

It could well be that I didn't understand important aspects of the paper, nevertheless, I read it and I formed an opinion that, even if wrong, might lead to some useful discussion.

Here it goes:

Do I call you an environmental scientists? If not, then what?

I am a geographer

What impresses your about this paper and why?

The most impressive thing is the scale of the analysis: the whole world during 12,000 years! It is a very ambitious project.

What new ideas come from it?

Well, in terms of ideas, it is pretty much in line with what some of the authors, and of course Ellis, have being saying for a while now. They published a paper in Science less than two years ago where they made the same point based on a collaborative assessment of many archaeologists. This time, it is based on HYDE 3.2, a model of past land use and past population density, but the main message is basically the same.

What surprises you about the paper and why?

There is almost no change in the amount of “wildland” across the last 12.000 years. This is quite surprising because I would say that 12.000 years ago America was almost empty, far less populated than it was by 1000 years ago.

What relevant work are you doing?

I study the evolution of the landscape in the Bolivian Amazon, looking at both natural and human causes of the change.

What is the paper’s broad significance?

This paper shows that it is very hard to establish baselines for what “natural” or “wild” actually mean. I think most of the academic debate is just about setting that baseline. For example, can I say that a forest is “natural” even if people where there and planted trees?

Do you expect it to be controversial? If so, why?

Yes. The fact that the amount of what they consider Wildland is almost constant during the last 12.000 years will be hard to accept. Of course, it depends on how they define the anthromes and the methodology. Nevertheless, the figures in the paper will raise a few eyebrows. Take for example Amazonia. They produced their maps by dividing the space into 96 km² hexagons, meaning that Amazonia, which is around 7M km², is made of 73,000 hexagons. However, based on a recent review (https://www.nature.com/articles/s41598-019-43086-w), in Amazonia there is only 1 site older than 11,000 BP (uncalibrated), 9 older than 10,000 BP and 46 older than 8000 BP. This means that by 8000 BP, only 0.06% of the hexagons that make Amazonia contain at least 1 archaeological site. How is it possible that, by 12000 BP, almost all Amazonia is classified as Cultured instead of Wildland? And that there is almost no change in the size of anthromes between 12.000 and 8.000 years BP when the number of archaeological sites grow from 1 to 46?

What are the paper’s shortcomings and strengths?

As I said, the most important aspect of this paper is the scale of the study. It is very important to make these reconstructions. Even if the uncertainties are very large, someone has to start. However, I think that there is an important issue with the definitions of the anthromes they use. They say that Wildlands are characterized by complete absence of humans, while Cultured anthromes are characterized by less than 20% of intensive use. But, there should be something in the middle! There is a threshold below which the presence of people should not count as causing any permanent change. If we consider a tropical forest, a few groups of hunter gatherers do not change the environment in any significant way, but still Ellis et al include that forest into the Cultured anthrome. It is possible that for most of the world, and for most of the time, Cultured anthromes were characterized by 0.5% or less of intensive use and people didn’t have any permanent impact. I think that what they call Wildlands should have included the presence of people as long as they did not cause any significant and permanent change. Then, we would have probably observed much bigger changes in the amount of Wildlands across the Holocene that would have likely been more in line with the archaeological and paleoecological evidence. 

P.S.

By zooming on the actual map that is online (https://anthroecology.org/anthromes/12kdggv1/maps/ge/), I see that I was wrong in saying that "almost all the Amazon is classified as Cultured" because it is roughly half of it. Anyway, my point is that it is a lot and doesn't change until 3000 BP. For large parts of the world, there are huge margins of error in their reconstruction. In my opinion, these are too big to justify the title of the paper and many of the comments I read in the press and on twitter. 

A multidisciplinary view of pre-Columbian Amazonia

In June 2016 a multidisciplinary group of researchers working in Amazonia got together in Barcelona to discuss to what extent and in what way pre-Columbian populations changed the landscape of ancient Amazonia.  The meeting was funded by the INQUA Commission for Humans and the Biosphere and SIMULPAST. Here you can find the talks that were given on the 8th of June. Unfortunately, the first talk, given by Marie-Pierre Ledru, was not recorded due to technical problems.

Marie-Pierre Ledru - Palaeoecologist: Paleoecological changes in the Amazon basin during the Holocene

Abstract:
Amazonia supports the largest rainforest system in the world. However this rainforest-dominant basin is composed of several types of vegetation including savanna, dry forests and mangrove mostly found on the transition zones. We will examine the different responses of the plant assemblages that characterize each of these vegetal communities and, how the global climate and the sea level changes  affected Amazonian landscape and plant diversity throughout the Holocene. Observed differences in tree cover, biomass, elevation, climate all over the territory altered the plant responses in different manners thus increasing the range of environmental responses.We will review and compare pollen records located in each vegetation type that compose the Amazon Basin. Hiatuses in sedimentation are common to all pollen records, although at different time intervals in function of their location. Expression of the environmental responses in northern, eastern, western and coastal Amazonia will be examined and compared to their adjacent biome evolution. Drier climate or drier soil conditions prevailed until the early Holocene although he re-start of lacustrine sedimentation is observed at different time intervals throughout Amazonia. The mid Holocene drought 8 to 5 kyr was prolongated in south and eastern Amazon until 3 kyr. Alternance of wet and dry episodes characterized the last millennia. We will also examine how the predicted increase of sea level and the global warming may affect this extremely moist and warm region in the future.

Umberto Lombardo - Geographer: El paisaje antrópico de la Amazonia Boliviana (In Spanish)

Abstract:
Los Llanos de Moxos, en la Amazonia Boliviana, son un conjunto de sabanas inundables ubicadas en la parte más meridional de la cuenca Amazonia. Esta región se caracteriza por la presencia de numerosas obras de tierra pre-Colombinas, como lomas monumentales, terraplenes, canales de irrigación y drenaje, campos agrícolas elevados (camellones) e islas de monte. Todos estos restos arqueológicos son la expresión de sociedades de cazadores recolectores antes y agrícolas después, que vivieron allí antes de la llegada de los españoles, desde hace 10000 años. A lo largo de estos 10.000 años, estás sociedades pre-Colombinas han sido afectadas por cambios medioambientales, y al mismo tiempo, han afectado el medio ambiente de manera permanente, tanto que el increíble paisaje de los Llanos de Moxos es el resultado de las complejas interacciones entre gente, ríos y clima. En mi charla exploraré estas dinámicas y interacciones entre pre-Colombinos y medioambiente en distintos lugares de la Amazonia Boliviana, intentando mostrar como la variabilidad espacial de las obras pre-Colombinas se corresponde con cambios en las características del paisaje y en las propiedades del los suelos.

Eduardo Góes Neves - Archaeologist: En búsqueda del año 6K en la Amazonia Antigua: Evidencias Tempranas de Cambios Paisajísticos (In Spanish)

Abstract:
Investigaciones arqueológicas recientes en la cuenca amazónica enseñan que esta región estuvo densamente ocupada en el pasado precolombino y que las poblaciones que allá vivían hicieran cambios en las condiciones ecológicas de la región. Si correcta, tal hipótesis sugiere que lejos de prístinos, los ambientes amazónicos tienen una larga historia de manejo hecho por los pueblos indígenas. Aunque tales formas de cambio sean visibles en los hallazgos arqueológicos relacionados a ocupaciones de pasado relativamente reciente, al rededor de 2 mil años BP, poco sabemos sobre ocupaciones mas antiguas fechadas al rededor de 6 mil años BP, o 6K. De hecho, por razones que todavía no son claras, en la arqueología amazónica asimismo como de otras partes de las tierras bajas de Sudamérica, parece más fácil encontrarse evidencias de ocupación humanas fechadas de la transición Pleistoceno-Holoceno, al rededor de 12-10 K BP, que del Holoceno medio, alrededor de 6K. Esta charla presentará los resultados preliminares de un proyecto de investigaciones el SW de la Amazonía, donde contextos fechados al rededor del año 6K han sido identificados. Los resultados preliminares nos permiten identificar algunas formas tempranas de manejo en la Amazonía e proponer hipótesis más amplias sobre la relación de largo plazo entre cambios climáticos y dinámicas culturales en la Amazonia antigua.

Charles R. Clement - Biologist: Plant domestication and dispersal in Amazonia (In English)

Abstract:
Throughout history, humans have developed uses for some 5000 native Amazonian plant species, and at least 85 of them have also been selected and propagated, which is the beginning of domestication. Domestication is a process in which humans select and propagate plant populations with traits that are useful to them; the interaction between human agency and natural selection results in anthropogenic plant populations embedded in landscapes that are increasingly useful to humans. In these populations, domestication can create subtle or dramatic changes in morphology, biochemistry and genetics. Likewise, landscape domestication may be subtle or dramatic, from modest changes in forest species composition to complete transformation of the landscape in swiddens and settlements. In recent years, studies combining molecular genetics and biogeography have allowed the identification of centers of domestication and routes of dispersal of some important Amazonian domesticates. Manioc (Manihot esculenta) was domesticated in southwestern Amazonia and selected for minimum toxicity; this ‘sweet’ manioc was widely dispersed quite early, arriving in Pacific coastal Peru by 8000 BP. ‘Bitter’ manioc appears to have been selected later in swiddens and was important in central and northern Amazonia. Cacao (Theobroma cacao) was semi-domesticated by 5000 BP in Amazonian Ecuador for the sweet pulp around the seeds and was dispersed both to Mesoamerica (where chocolate was invented) and to eastern Amazonia, which went unnoticed until recently because there was no chocolate there! Peach palm (Bactris gasipaes) was also domesticated in southwestern Amazonia and dispersed both northwestward to Central America, becoming a major starch crop used for fermented drinks, and northeastward to central and eastern Amazonia, where it was used as a snack. Guaraná (Paullinia cupana) is a stimulant and the only crop known to be domesticated in central Amazonia; it is a high level polyploid with very little genetic diversity, suggesting a very recent domestication (1000 BP). Brazil nut (Bertholletia excelsa) was used by 11,200 BP, and is incipiently domesticated and widely dispersed across central and eastern Amazonia in forest stands associated with archaeological sites. Its center of domestication is not yet confirmed, with southwestern and northeastern Amazonia being considered. Future integration with archaeology, especially archaeobotany, and palaeoecology will increase the relevance of these studies to understand the history of Amazonian crops, people and landscapes.

Manuel Arroyo-Kalin - Archaeologist: Los Suelos Antrópicos de la Amazonía: algo más que tierra negra… (In English)

Stéphen Rostain - Archaeologist: Amazonía, el dinamismo de un paisaje tropical único (In Spanish)

Abstract:
Se admite hoy en día que los paisajes en los cuales vivimos son resultado tanto de antiguas actividades humanas como de procesos naturales. Los ecosistemas amazónicos, al igual que otras tierras antiguamente ocupadas por el hombre, han evolucionado en función de las acciones de este. Así, solo la asociación de las ciencias de la Vida y de la Tierra permite una evaluación de las contribuciones respectivas del  hombre y de la naturaleza en la construcción del paisaje ecuatorial. Es el caso de un proyecto llevado a cabo en las sabanas costeras de las Guyanas, el mismo que contó con la colaboración de arqueólogos, arqueobotánicos, ecólogos, pedólogos, etc. Si bien la arqueología alimenta a las ciencias de la naturaleza con temas de estudio cruzados, para la lectura del pasado se  nutre también  de  otras  ciencias que  le proporcionan nuevos métodos complementarios de los clásicos y la ayudan a reconstruir de manera mucho más completa el contexto medio ambiental en el cual la cultura antigua se hallaba inserta. Es entonces, una nueva historia del paisaje la que se dibuja poco a poco. 

Maximilien Guèze - Ethnobotanist: Shifts in indigenous culture relate to forest tree diversity: A case study from the Tsimane’, Bolivian Amazon (In Spanish)

Abstract:
Understanding how indigenous peoples’ management practices relate to biological diversity requires addressing contemporary changes in indigenous peoples’ way of life. This study explores the association between cultural change among a Bolivian Amazonian indigenous group, the Tsimane’, and tree diversity in forests surrounding their villages. We interviewed 86 informants in six villages about their level of attachment to traditional Tsimane’ values, our proxy for cultural change. We estimated tree diversity (Fisher’s Alpha index) by inventorying trees in 48 0.1-ha plots in old-growth forests distributed in the territory of the same villages. We used multivariate models to assess the relation between cultural change and alpha tree diversity. Cultural change was associated with alpha tree diversity and the relation showed an inverted U-shape, thus suggesting that tree alpha diversity peaked in villages undergoing intermediate cultural change. Although the results do not allow for testing the direction of the relation, we propose that cultural change relates to tree diversity through the changes in practices and behaviors that affect the traditional ecological knowledge of Tsimane’ communities; further research is needed to determine the causality. Our results also find support in the intermediate disturbance hypothesis, and suggest that indigenous management can be seen as an intermediate form of anthropogenic disturbance affecting forest communities in a subtle, non-destructive way.

Evert Thomas - Biologist: Spatial patterns in the natural and human history of Brazil nut across the Amazon Basin: megarodents, glacial refugia, terra preta and geoglyphs (In Spanish)

Amy Goldberg - Mathematician and Anthropologist: Post-invasion human demography in prehistoric South America: a continental view (In English)

Abstract:
As the last habitable continent colonized by humans, the site of multiple domestication hotspots, and the location of the largest Pleistocene megafaunal extinction, South America is central to human prehistory. Yet remarkably little is known about human population dynamics during colonization, subsequent expansions, and domestication. Here we reconstruct the continental-scale spatiotemporal patterns of human population growth in South America using a database of 1,147 archaeological sites and 5,464 calibrated radiocarbon dates spanning fourteen thousand to two thousand years ago (ka). Notably, our database demonstrates substantial regional variation in coverage, suggesting further work for Northeastern South America and Amazonia.
We demonstrate that early human expansions showed the same pattern characteristic of invading animal populations, with resource-limited growth. Only with widespread sedentism, beginning ~5 ka, did a second demographic phase begin, with evidence for exponential population growth in cultural hotspots, characteristic of the shift to agriculture worldwide.

Carla Jaimes Betancourt - Archaeologist: La dinámica cultural al suroeste de la Amazonia a la luz del registro arqueológico (In Spanish)

Abstract:
La arqueología amazónica enfrenta grandes cuestionamientos paradigmáticos. Al mismo tiempo que aumentan las evidencias de monumentalidad y manejo de recursos naturales, se devela una enorme diversidad de contextos culturales y patrones de transformación del paisaje. Aunque los procesos históricos y sociales de cómo se generaron estas manifestaciones en el paisaje cultural amazónico se encuentran todavía en discusión, la mayoría de estas transformaciones son atribuidas por lo general a la dispersión de la familia lingüística Arawak. En esta ponencia, se coteja el registro arqueológico de dos áreas culturalmente distintas de los Llanos de Mojos, con algunos de los modelos planteados que intentan explicar el proceso de “arawakización” en la Amazonía. Comprobándose que en Mojos y de manera coetánea, se desarrollaron diferentes procesos culturales locales, en escenarios multiétnicos y posiblemente plurilingües, que desembocaron en la creación de sociedades con características inalienables a las supuestas influencias Arawak. Dejando al descubierto, que únicamente mediante el estudio de los desarrollos culturales locales durante el holoceno medio, podremos entender el surgimiento de estos complejos procesos ocupacionales.

Philip Riris - Archaeologist: Dates and Dispersions: examining the spatio-temporal boundaries of the Guaraní expansion into the La Plata basin with Monte Carlo methods (In English)

Abstract:
he direction and timing of the Guaraní expansion into the La Plata basin from an Amazonian origin is a matter of no small debate in the study of South American indigenous cultures. The short timeframe of the Guaraní expansion (2000 – 500 BP) during the late Holocene, as well as the distances involved, are both used to explain it as the result of the migration of significant numbers of people in a classic “wave of advance”. The process is further broken down into “pulses” punctuated by periods of relative stasis in which colonization through the valleys of major rivers was halted or slowed. These factors, combined with a broad base of empirical data from decades of research, provide the impetus for refining established chronologies of the Guaraní dispersal. 
We use a published database of georeferenced dates to model the its spread at the beginning of the Common Era from a presumed entry point until the time of European contact at its known limits at the La Plata delta and Atlantic coast of Brazil. Using Monte Carlo methods, we examine the dispersal as a function of time and distance in order to constrain the probable start dates for entry into different zones. Additionally, we investigate the notion that Guaraní groups enveloped large sectors of terrain contiguously as the result of demographic pressures that were interspersed, as noted, with hiatuses of comparatively little movement. We place our findings in the context of preceding archaeological, ethnographic, and ethnohistorical knowledge on this uniquely South American process of indigenous dispersal. Suggestions for further work to improve the scenarios we present are offered, following the note by Brochado (1984) that in the study of Guaraní archaeology, “computer modelling is probably the only way to achieve refined estimates of population growth” in the La Plata basin. 

Fieldtrip to the Bolivian lowlands

In this post I am going to upload photos and short comments about the ongoing fieldtrip to Beni, Bolivia, of the MSc students from the Institute of Geography at Bern University. The students arrived in Trinidad the 11th of August and will leave on the 21st.

Day 1 - 11th of August. Visit to the Museum Kenneth Lee in Trinidad.

Day 2. Excursion to the Mamoré river

Leaving the port

Describing and sampling a paleosol sequence outcropping along the Mamoré River bank

Day 3. Visiting the Indigenous community of Bermeo

Before playing football...


...and, with a BFC like outfit, Bermeo won :-)

Day 4 and 5.Community of Ibiato, on a paleo levee-backswamp of the Grande River

Excavating and analyzing a transect of 5 soil profiles along a paleo Grande River lavee-backswamp catena.

. Day 6. Meeting with indigenous leaders and visiting experimental raised fields

Doña Berta Vejarano Congo, leader of the indigenous march against the construction of the road across the TIPNIS indigenous territory and natural reserve, and Pedro Nuny Caity give a talk about the political situation of the indigenous people in the Bolivian Lowlands under the government of Evo Morales

Visiting experimental raised fields built by Oxfam GB in a suburb of Trinidad, now managed and subsidised by Trinidad City Council 

Day 7 - Sunday, day off at Laguna Suarez, one of  the many rectangular and oriented lakes found in the Bolivian Amazon.

Laguna Suarez, about 5 km from Trinidad

Day 8 - In the the morning visit to the Estancia La Chachra, where we learned about the extensive cattle ranching that is practiced in the Beni. We also went on a little safari.

Selecting the cows by size and checking if they are healthy

A little safari along the road inside La Chacra

One of the many alligators living in La Chacra, in the ponds that were excavated to take the material used to build the road 

In the afternoon we went to visit on of the biggest pre-Columbian monumental mounds: El Cerrito

Our guide invited us to have toronjas (a kind of sweet grape fruit) on the way back from the mound

Day 9 - Visiting the indigenous community of San Miguel del Matire and the CIPCA cacao project

Olver Vaca from CIPCA explains to us how the cacao project works

Visiting the facilities in San Ignacio the Moxos where the indigenous cacao is processed

Day 10 - Last day - We went fishing in the Mamoré

Fishing from the boat with "lineada y anzuelo"

The fish we caught

Preparing the fish at the restaurant "La choza del Pescador"

And ready to eat!!

This is the end of the 10 day field trip in the Beni - Bolivia. I hope you enjoyed it! See you in Bern!!

“Predicting pre-Columbian anthropogenic soils in Amazonia”

“Predicting pre-Columbian anthropogenic soils in Amazonia” is the title of a recent paper by McMichael et al. published in Proceeding of the Royal Society B. It is not open access but you can read the abstract here. In this paper McMichael et al. present a predictive model for the presence of Terra Preta in Amazonia.  The model predicts the likelihood of finding Terra Preta sites in any given spot within Amazonia.  In general, I liked the idea behind the paper. These models give us an objective basis for further research and discussions. It is thanks to this kind of work that we can go beyond subjective views about the extent of human impact in pre-Columbian Amazonia and start to formulate hypothesis that, through survey and measurement, can be later tested. The first important result of this paper is that, given the data available, we can now estimate that terra preta is likely to be found only in a 3.2% of the forested areas of Amazonia. This is far less than other previous estimates (Erickson, 2008).

However, I find the discussion of McMichael et al. a bit disappointing with regards to two points. The first is the meaning they give to the presence of terra preta; the second is the reasons they give to explain the absence terra preta outside of Brazil.

What is terra preta? Is it the result of permanent settlement where people cooked and dumped food remains for centuries, eventually causing the enrichment of the soil in with charcoal, phosphorous, organic matter and the rest of elements used to define terra preta? Or is it the result of soil management techniques aimed at improving fertility and agricultural potential? McMichael et al. seem to imply that terra preta is the latter: the result of soil fertility enhancement. They say: “The lack of terra pretas in western Amazonia may be because the Andean-derived soils of western Amazonia did not require nutrient enrichment… [the bold is mine]”. However, this kind of interpretation of terra preta being the result of Pre-Columbian agricultural intensification has been challenged by many authors. Neves & Petersen (2006) discovered that at the Hatahara occupation site (close to Manaus) pre-Columbians actually used terra preta to build burial mounds, which is a strange use for an agricultural soil that took centuries to form. Of course, we cannot exclude that pre-Columbians took advantage of the fertile terra preta for their gardens associated to their homes; in the same way that they could have taken advantage of the fertility of pre-existing middens (see Arroyo-Kalin, 2012 for a discussion on this).But this does not mean that people intentionally created terra preta for agriculture!

Recently, Glaser & Birck (2012) concluded their review about the state of the scientific knowledge about the properties and genesis of Anthropogenic Dark Earths in Central Amazonia saying: “there is no scientific evidence indicating that forgotten agricultural techniques for large scale soil fertility improvement are responsible for terra preta genesis”. 

This leads us to my second concern: what does it mean when no terra preta is found? Here, McMichael et al. suggest that the lack of terra preta indicates that people decided to produce food in some other way, due to cultural and/or environmental reasons. They say: “[In the Llanos de Moxos] instead of terra preta formation, large societies sustained themselves by using techniques such as fish weirs and raised-field agriculture”. But, is it cultivating little gardens that large societies sustained themselves? I think the answer is no. In fact, pre-Columbians living in terra preta sites performed agriculture in the surrounding area, eventually forming terra mulata sites. Terra mulata sites are far larger than terra preta ones. Terra mulata sites do not contain pottery and are far less fertile than terra preta ones, but still, they are richer in organic matter than the normal Amazonian oxisols (more on this here). It is terra mulata that formed because of ancient agricultural use, not terra preta.

The main problem we face when tackling the question of terra preta is its definition. The definition that is generally given to terra preta coincides with the description of the geochemistry of a midden (From Wikipedia: an old dump for domestic waste which may consist of animal bone, human excrement, botanical material, vermin, shells, sherds, lithics, and other artifacts and ecofacts associated with past human occupation) and there are middens everywhere in the world! As a consequence of this, terra preta sites are now appearing everywhere... We should also keep in mind that the whole terra preta concept is rooted in the context of the big surprise that the first researchers had when they found black organic sediments in the middle of Amazonian heavily weathered soils. In fact, terra preta is often defined (and mapped in the field) in relation to the surrounding soil (Fig. 1). In my view, there is not much that actually differentiates terra preta from other occupation horizons elsewhere. I have seen several places in the Bolivian Amazon that, because of the colour of the soil, concentrations of P, Ca, charcoal etc., would fit quite well into the definition of terra preta (see for example this). It is just that they are not called terra preta, yet :- ). It could be that the absence of terra preta sites outside Brazil is merely the result of researchers giving these kinds of soils/deposits different names in different regions, such as “middens” or “occupation horizons”.

Figure 1: oxisol left, terra preta right (from Wikipedia)

I think that the, otherwise excellent, paper by McMichael at al. could have benefited from incorporating into their model a database of terra mulata sites, instead of terra preta sites. Or, even better, if they had used a database of pre-columbian occupations, including the archaeological sites known outside of Brazil. This would have provided a more reliable tool for modelling pre-Columbian agriculture (if a terra mulata database had been used) or settlements patterns (if a database of archaeological sites had been used) within the Amazon basin; and for modelling pre-Columbian disturbance of the natural environment.

References
 McMichael CH, Palace MW, Bush MB, Braswell B, Hagen S, Neves EG, Silman MR, Tamanaha EK, & Czarnecki C (2014). Predicting pre-Columbian anthropogenic soils in Amazonia. Proceedings. Biological sciences / The Royal Society, 281 (1777) PMID: 24403329

Erickson, C.L. (2008). Amazonia: the historical ecology of a domesticated landscape In: H. Silverman, W.H. Isbell (Eds.), Handbook of South American archaeology. Springer, Berlin, pp. 157-183 DOI: 10.1007/978-0-387-74907-5_11

Neves, E.G., & Petersen, J.B. (2006). Political economy and pre-Columbian landscape transformations in Central Amazonia In: W. Balée & C.L. Ericksonl (Eds.),Time and complexity in historical ecology. Columbia University Press, New York, pp. 279-309

Arroyo-Kalin, M. (2012). Slash-burn-and-churn: Landscape history and crop cultivation in pre-Columbian Amazonia Quaternary International, 249, 4-18 DOI: 10.1016/j.quaint.2011.08.004

Glaser, B., & Birk, J.J. (2012). State of the scientific knowledge on properties and genesis of Anthropogenic Dark Earths in Central Amazonia (terra preta de Índio) Geochimica et Cosmochimica Acta, 82, 39-51 DOI: 10.1016/j.gca.2010.11.029

The rectangular and oriented lakes in the Bolivian Amazon are not tectonic, and now what?

Our latest paper has been published a few days ago in Geomorphology. The title is: "The origin of oriented lakes: Evidence from the Bolivian Amazon". Here goes a very short version of it.
The presence of hundreds of rectangular and oriented lakes is one of the most striking characteristics of the Llanos de Moxos landscape (Fig. 1). Many different mechanisms have been proposed for their formation, including subsidence resulting from the propagation of bedrock faults through the foreland sediments, scouring caused by large-scale flooding, paleo deflation combined with wind/wave action and human agency. Nevertheless, amid this diversity of hypothesis, the most commonly accepted cause of lake formation to date has been tectonics.

Figure 1. Landsat image of oriented and rectangular lakes in the Llanos de Moxos

Plafker’s tectonic model (Fig. 2) has never been tested. If faulting is involved, the displacement should be visible and measurable through sediment profiling. The only element needed is a stratigraphic marker that allows the measurement of the vertical displacement.

Figure 2. Tectonic model for lake formation (Plafker, 1967). According to Plafker, the lakes' rectangular shape results from the propagation of bedrock fractures through unconsolidated sediments.

Thanks to our recent discovery of a paleosol below mid-Holocene fluvial sediments in the south-eastern LM (Lombardo et al., 2012), where several lakes are found, it is now possible to test the tectonic hypothesis. If lakes were formed by local subsidence induced by bedrock faults, we should find the paleosol at a greater depth below the lake than in the area surrounding it. 

This is how we cored the lakes

Stratigraphic profiles from transects that cut across the borders of three lakes show otherwise (Fig. 3): the depth of the paleosol is the same. Hence, tectonics, as the mechanism behind the formation of the lakes, can be ruled out. The origin of the Moxos rectangular and oriented lakes is still very much unresolved. A more detailed discussion about the possible mechanisms behind the lakes' formation can be found in Lombardo & Veit (In Press). 

Figure 3. Stratigraphic transects from the outside to the inside of the lakes. Dotted white lines define the lakes’ basins. The early to mid-Holocene paleosol acts as a stratigraphic marker (see Fig. 2). Cores 52, 63, 81, 170, 205 and 210 provide the reference depth of the paleosol outside the lakes; cores 77 and 204 have been performed in areas of the original lakes’ basins that have been infilled; cores 78, 169, 171 and 209_b come from inside the lakes. Continuous black lines reconstruct the original lake bottom (previous to lacustrine infilling); dashed black lines connect the paleosol. Source of digital images: Google earth.

References:

Lombardo, U., May, J.-H., & Veit, H. (2012). Mid- to late-Holocene fluvial activity behind pre-Columbian social complexity in the southwestern Amazon basin The Holocene DOI: 10.1177/0959683612437872
Lombardo, U., & Veit, H. (2013). The origin of oriented lakes: Evidence from the Bolivian Amazon Geomorphology DOI: 10.1016/j.geomorph.2013.08.029
Plafker, G. (1964). Oriented Lakes and Lineaments of Northeastern Bolivia Geological Society of America Bulletin DOI: 10.1130/0016-7606(1964)75[503:OLALON]2.0.CO;2

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.