The discovery of ‘dark earth’ in the Amazon Rainforest raises questions about Ancient Indigenous People

Since the start of the early 2000s, Schmidt, Heckenberger and others, have compiled a large amount of data and observations about the Amazon while working with indigenous tribes located around the Upper Xingu River basin (ScienceDaily, 2023). Most notable of these observations was the recording of various patches of ‘dark earth’ that were scattered throughout the area. They found that many of these patches were located in close proximity to villages and habitable areas in the Kuikuro Indigenous Territory. 

Fig 1. Areas of study located in proximity to historic sites and habitable areas. (Science, 2023)

To determine their function, Schmidt and his associates began to observe modern Kuikuro practices of managing the soil. Modern practices by these indigenous peoples entails the creation of “middens,” or waste piles, that are made of waste and food scraps left to decompose. This decomposition creates nutrient rich ‘dark earth’ that can be used in agriculture. Furthermore, it was observed that the farmers of this tribe would spread ashes and organic waste in places where they planned to grow crops, thereby acting as fertilizer and a source of nutrients (Chu, 2023).

Fig 2. Test pit of dark earth at Ngokugu site, where there was the presence of ceramics. (Chu, 2023)

After taking samples of modern dark earth and dark earth from archaeological sites, Schmidt and researchers from MIT measured the chemical compositions of both soil, then compared them. They believe that ancient amazon peoples used similar methods as the Kuikuro people to make fertile land for planting due to both soils being enriched with the same elements and having similar compositions; as well as the patterns in which these dark earth areas were made being similar across both sites, where dark earth areas were placed in a radial pattern concentrated in the center that would extend outwards to form a wheel shape. The creation of these fertile areas represents a significant shift in their society from hunter gatherer bands to segmentary societies, which typically use agriculture to acquire food. This shift in food production typically results in increases in population and the development of more complex culture. While the layout of the dark earth in an almost wheel-like structure may be practical for the environment that they are in, the shape may also be indicative of some cultural or religious expression, though that has yet to be determined.

Fig 3. Kuikuro II village in the Território Indígena do Xingu. (Chu, 2023)

While the creation of dark earth might seem underwhelming, it represents a major innovation and significant cultural and social change among the ancient inhabitants of the Amazon. Recognizing that the natural soil of the Amazon rainforest is severely depleted of resources and is unsuitable for growing crops, they developed techniques to insert nutrients into the environment. Rather than forcing the environment to adapt to their needs and changing society, they developed methods to better the environment so that they might thrive there.

Their methods, although unintentionally, created a vast carbon sink and a potential carbon reservoir in the soil (Science, 2023). Perhaps modern society can take this as a learning opportunity and possible method for solving, or at least mitigating, humanity’s impact on Earth’s climate and global ecosystem.


Massachusetts Institute of Technology. “Ancient Amazonians intentionally created fertile ‘dark earth’.” ScienceDaily.

“Intentional Creation of Carbon-Rich Dark Earth Soils in the Amazon.” Science, 2023.

Chu, Jennifer. “Ancient Amazonians Intentionally Created Fertile ‘Dark Earth.’” MIT News | Massachusetts Institute of Technology. Accessed September 24, 2023.

Further Readings:

Smithsonian Institution. “Indigenous Peoples Were Stewards of the Western Amazon.” Smithsonian Institution, January 1, 1970.

Schwartzman, Stephan, André Villas Boas, Katia Yukari Ono, Marisa Gesteira Fonseca, Juan Doblas, Barbara Zimmerman, Paulo Junqueira, et al. “The Natural and Social History of the Indigenous Lands and Protected Areas Corridor of the Xingu River Basin.” Philosophical transactions of the Royal Society of London. Series B, Biological sciences, April 22, 2013.

Peace in Sustainability

War is not a sustainable part of any society. War has been a leading factor in the downfall of many civilizations. It’s a plague on humanity that seems inevitable in any modern society, and for the most part it is. Why? Agriculture is the culprit.

Behold, the bane of human existence

Behold! The bane of human existence

That’s a grossly oversimplified explanation, but one that does not need to be stretched very much to be justified. Agriculture brought with it sedentary lifestyle. Once the dispute for land and water began, the motives for warfare became unavoidable. The problem is that agriculture is just unsustainable. The most sustainable strategy for a peaceful civilization is that of a hunter-gatherer lifestyle. The practice of hunting and gathering left very little impact on the environment it took place in. Because of this, the environment in which it took place was able to provide sufficiently enough sustenance for the groups in that area, and when it was no longer a reliable food source the people would pick up and move to another location. The soil was left with little change and animals were hunted in reasonable numbers.

Most people nowadays would consider this to be the lifestyle of a lesser type of civilization with little value, due to contemporary American society revolving around a sedentary style of living. However, it was these very types of societies that were able to outlive Mesopotamia by hundreds of years. Mesopotamia has been nicknamed the Cradle of Civilization and is often times praised for its innovative and intelligent system for irrigation that it developed. This system had fatal flaws though, in that it caused salt to accumulate in the soil and continuously slowed the quality and quantity of crops that could be harvested each season. It goes to show that even one of the most prominent of previous civilizations was not immune to the unsustainable nature of sedentary life.

The Cradle of Civilization, the Fertile Cresent

The Cradle of Civilization, the Fertile Cresent

It’s difficult to pinpoint the exact time which warfare became more of a norm among societies, but it seems to have become common practice about 5,000 years ago when states began to emerge. States emerge with the development of political units, which are in turn developed as sedentary life and agriculture is established. With the creation of agriculture, there has to be someone in charge, in order to oversee the cultivation and this leads to the village caring for this figure and providing tribute. This trend continues as more political figures are created.

Warfare is not a common practice for hunter-gatherers. They are able to live a peaceful existence because there is little rivalry or even interaction among foreign groups. Without a sedentary life or a political hierarchy caused by agriculture the motivation of “status” for citizens disappears, lessening internal conflicts. Territorial  disputes also disappear, for nomadic groups acknowledge that they hold no claim to land. It seems that the more that the past gatherer lifestyle is compared alongside contemporary modern societies, the more the former feels like the most rational option. Reverting back to more more sustainable style would involve changing the lives that we’re accustomed to, and for many that’s a process near impossible.

– Bernardo

image 1:

image 2:

Action Archaeology: Agriculture, Population and Sustainability

“The possible futures of the global system are illuminated by careful study of its past and comparisons with power processes in previous eras.”[1] The thought-provoking statement from  archaeologists Jonathan Friedman and Christopher Chase-Dunn clearly demonstrates the importance of the past to the future. In other words, to look into how past people dealt with contemporary problems can give us an insight into how we deal with them at the present and in the future. This is exactly what we call “Action Archaeology.” More specifically, through analyzing the success and failure in agriculture of past civilizations, we are able to adjust and improve our agricultural strategies, to produce more crops for the growing population, and ultimately to develop a sustainable society.

The ancient Maya succeeded in maintaining their race by agricultural innovations. Between about 100BC and AD450, unlike “today’s relatively sparse population,” the northern Maya lowland in the Yucatan peninsula was heavily populated.[2]


A wetland of the Yalahau region.

In order to support themselves, first, the Maya mixed “a colony algae, fungus, bacteria, detritus and other living organisms” to make “periphyton,” which proves to be “a natural, renewable, and manageable source of agricultural fertilizer.”[3] Second, they piled “chich mounds” under economically important trees “to conserve moisture and to provide support for trees cultivated in the shallow soils.”[4]


A modern chich mound at the base of a tree.

As a result, such agricultural innovations “[led] to sustainable development in this region.”[5] If we could apply their ways of cultivation together with modern technology, we would be more likely to handle today’s population issues and to sustain our race.

The Sumerians, on the opposite, destroyed themselves by damaging the environment. Their “heavy irrigation in a hot, dry climate leads to a gradual accumulation of salt in the soil.”[6]


Salinization of soil.

At last, the salinization transformed the used-to-be fertile land to the extent that even barley could not grow.[7] “The very soil lost its virtue,” and Sumerian Civilization collapsed.[8] The negative effect on environment lasted even for thousands of years, for in the 19th century the population of Iraq was less than tenth of that in the age of Gilgamesh.[9] Thoroughly analyzing how the Sumerians destroyed their agriculture, we could avoid the same tragedy happening in the future and learn to develop sustainably.


Sumerian civilization in the middle of the desert.

Besides agriculture and sustainability, in action archaeology, the past can also help us reduce warfare, alleviate poverty  and strengthen identiy. In short, the achievements and mistakes of past civilization are ladders, leading to a happier life for every single person in the world.


1 Jonathan Friedman and Christopher Chase-Dunn, Hegemonic Decline: Past and Present (Paradigm Publishers, 2005), Introduction, as quoted in Jeremy A. Sabloff, Archaeology Matters: Action Archaeology In The Modern World (Walnut Creek, CA.: Left Coast Press, 2008), 45.

2 Jeremy A. Sabloff, Archaeology Matters: Action Archaeology In The Modern World, 49.

3 Scott L. Fedick and Bethany A. Morrison, “Ancient use and manipulation of landscape in the Yalahau region of the northern Maya lowlands,” in Agriculture and Human Values (21: 207–219, 2004).

4 Ibid.

5 Jeremy A. Sabloff, Archaeology Matters: Action Archaeology In The Modern World, 49.

6 Paul Krugman, “Salt Of The Earth,” in New York Times (August, 08, 2003).

7 Ibid.

8 Leonard Woolley, Ur of the Chaldees, as quoted in Paul Krugman, Salt Of The Earth.

9 Paul Krugman, Salt Of The Earth.


Image 1

Image 2

Image 3

Image 4

Channel-ing the Sustainability of Ancient Societies

How often do you think about archaeology being used to help modern societies use resources better? It’s not like Indiana Jones (sorry, for the clichéd example) went around searching for the mysterious, lost sustainable farming methods. However, archaeology can help us protect our environment and resources by showing us how our predecessors dealt with these issues in their time.

Northern Channel Islands (airial)

The Channel Islands

(Source: )

The Chumash people of the California Channel Islands are one such culture that can give us important insights to resource management. As early as 9500 B.C. Channel Islanders figured out how to regulate their hunting and fishing so as to not completely decimate their food sources. Historical ecology studies examine the dynamic between these people and their environment from 10,000 years ago onward. It appears that, although there were occasional declines in the populations of various animals, these populations also came back[1]. The Chumash clearly understood how to manage their resources.

Discoveries of shell middens have taught us a lot about the Chumash’s way of life[2]. Archaeologists have found many different types of projectile points, showing that the Chumash hunted many different types of animals[3]. By diversifying their prey, they had the ability to hunt certain populations while letting others grow.


Different tools and projectile points discovered on the Channel Islands

(Source: )

Interestingly, other evidence indicates that the Chumash and those who came before them did have more impact on the evolutionary diversity of the islands. They brought dogs to the islands! Dogs did a lot of good for the people on the islands, like security, friendship, and hunting assistance. As the numbers of dogs on the islands increased, though, their presence began to impact other animal populations[4]. They killed and drove away many birds and sea mammals. So, although the Chumash’s hunting and fishing techniques are a great example of resource management, their mistakes, like bringing in an invasive species, can also be instructive to today’s society.


Aww! How could a dog impact the environment? Well, transplant about a hundred into an island ecosystem…

(Source: my own photo)

Human impact of this environment has increased significantly in historic times, with oil spills, over-fishing, and other factors. Luckily, the Channel Islands are protected now, but what about the rest of the world? We can learn from the Chumash’s restrained fishing techniques because, although we do have some regulations today, in my opinion, they need to be stricter and focus more on cycling different fish populations. But there has to be more widespread awareness and understanding of this archaeology first.


[1] Torben C. Rick and Jon M. Erlandson, “Archaeology, Ancient Human Impacts on the Environment, and Cultural Resource Management on Channel Islands National Park, California”, CRM Journal Fall 2003: 86-89. Accessed November 14, 2013.

[2] IBD

[3] “New Archaeological Evidence Reveals California’s Channel Islands as North America’s Oldest Seafaring Economy”, Smithsonian Science, Last modified March 3, 2011.

[4] John Barrat, “Science Brief: Dog Bones Reveal Ecological History of California’s Channel Islands”, Smithsonian Science, last modified July 6, 2009.