The Impact of Astronomy on Cahokia and Mesoamerican Societies

Throughout history, the study and interpretation of celestial bodies and movements has played a pivotal role in shaping cultures around the world. By interpreting the heavens, these civilizations have made numerous discoveries that impact the lives of everyday citizens. The influences of astronomy is reflected through agricultural practices, religious beliefs, and the establishment of societal hierarchies

In Mesoamerica, particular attention was paid to the movements of the moon and Venus, both of which were important for agricultural practices. Venus, also known as the Evening Star, was predominant in Mesoamerican cultures as its movements signified the beginning and end of the rainy seasons (Sprajc, 2011). To normal citizens, knowledge of the cosmos and the ability to predict future occurrences in the region could be interpreted as divine providence; indeed, the ability to predict celestial events may have very well been used to legitimize the privileges given to religious figures and the social elite. In turn, religious figures were likened to men-gods, who performed rituals and sacrifices to ensure the cosmos was in balance (Šprajc, 2011).

The use of astronomy to create social hierarchy is not unique to Mesoamerica. The Mississippi River civilization of Cahokia shared similar astronomical discoveries and cultural expressions with Mesoamerican civilizations. In 1961, Warren Wittry discovered Woodhenge, akin to Stonhenge in Great Britain, that acted as an observatory and calendar (Pauketat, 2010). Large poles made of a sacred wood, red cedar, ringed a central pole made of the same material. The most important of these were the poles that marked the summer and winter solstice, and the pole that marked the equinox (Keller, Young, Kronk 2022). This allowed for farmers and religious leaders to more accurately determine the best time to undertake certain activities, including the planting of crops.

Fig 1. Diagram of the woodhenge at Cahokia. This details the paths in which certain celestial events cast shadows on this monument (Crozier, 2018).

Aside from the practical applications of astronomy, the study of the heavens was also used to demonstrate status differences and religious beliefs. In Cahokia, there is a particular burial mound, designated as Mound 72, that is oriented to align with the solstices. Inside were the remains of two figures, one on top of the other, who were adorned with pelts and were buried alongside thousands of shell beads (Pauketat,  2010). The unique orientation of this mound, alongside evidence of numerous sacrifices in the area and the expensive goods in the mound, indicate that these two figures were of extreme importance.

Fig 2. Map of Mound 72 burial features at Cahokia (Thompson, Hedman, Slater, 2015).

The evidence of ritual killings in the presence of burial mounds, similar to other Mesoamerican cultures, alludes to these events being public displays of power. It is likely that, “with sacrifices, leaders could eliminate some rival claimants to office, impress the viewing public, and reaffirm the balance of the cosmos all at once” (Pauketat, 2010). Moreover, these public killings demonstrate how astronomy could influence and shape civilizations. Leaders of respective civilizations were able to utilize this valuable astronomical knowledge to establish a strict social hierarchy, and in the process, create religious justifications to reinforce their divine right to rule.


Šprajc, Ivan. 2011. “Astronomy and Its Role in Ancient Mesoamerica: Proceedings of the International Astronomical Union.” Cambridge Core, Cambridge University Press. June 29, 2011.

Crozier, Elizabeth. 2018. “The Stonehenge of Illinois Is a Man Made Wonder Few Know About.” OnlyInYourState®. March 21, 2018.

Keller, Ken, Eric Young, Gary Kronk. 2022. “Woodhenge”. Cahokia Mounds State Historic Site and Cahokia Mounds Museum Society.

Thompson, Andrew R, Kristin M Hedman, and Philip A Slater. 2015. “New Dental and Isotope Evidence of Biological Distance and Place of Origin for Mass Burial Groups at Cahokia’s Mound 72.” Wiley Online Library, July 14, 2015.

Pauketat, Timothy R. 2009. Cahokia: Ancient America’s Great City on the Mississippi. Penguin Books.

Other Readings:

Aldana, Gerardo. 2022. “Maya Calendar and Mesoamerican Astronomy.” Encyclopedia of the History of Science, February 10, 2022.

Kropf, Evyn, Francesca Schironi, John Steele, Julia Falkovitch-Khain, and Pablo Alvarez. 2023. “Early Astronomy in the University of Michigan Collections.” Early Astronomy in the University of Michigan Collections | Home.

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.