Xochimilco: Cosmos and Multispecies Mutuality

Xochimilco area in Mexico City is the last remnant of what the great Aztec city of Tenochtitlán used to be. It is located in the Trans-Mexican Volcanic Belt which traverses the Mexican territory from East to West, in approximately 1000 kilometers long. These active volcanic formations were generated by the subduction of the Rivera and Cocos plates beneath the North American Plate. Also known as the Sierra Nevada, this mountain range is the home of the Valley of Mexico. Surrounded by various mountains and volcanoes, including the Popocatépetl active volcano. The Basin of Mexico is formed by a lacustrine system of five different endorheic lakes, both fresh and saline, today almost extinct.

All around the lakes, many Mesoamerican cultures thrived. Located in strategic sites along the coast of the lake, these communities were able to profit from food from land and from water in the surroundings. The water context allowed for great communication between boroughs by use of small vessels.

The great Aztec city of Tenochtitlán was the biggest of all the establishments. Founded in the year 1325, By the year 1519 the city had a population of approximately 400,000 inhabitants. The actual territory of the city started from an island in the middle of the Texcoco lake, expanding into the water through a series of floating plots used for all kinds of activities, including agriculture.  As depicted in maguey map from the 16th century, these floating gardens were organized in a constricted rectangular grid that constituted a big part of the Valley’s urban design.

Today, as almost 100% of the lakes are desiccated, Xochimilco stands as a living example of the almost extinct islands. This area was in fact, part of the southern lake of Xochimilco, where the Xochimilca people developed the biggest and most efficient agricultural land of the Aztec Empire. It actually supplied 80% of the Tenochtitlán’s food requirements, a city of almost half a million people. These floating gardens are called chinampas, and still 2,215 hectares are in use for local food production today. As the city keeps growing, Xochimilco tries to fight back by entering diverse international certifications. Today, this area is included in the Ramsar Convention as a lacustrine wetland of international importance, decreed as a World Heritage Site by UNESCO and considered a Globally Important Agricultural Heritage System by FAO.

It was the main site for agriculture in the Basin during the 14th century. In Xochimilco, or Field of Flowers in Nahuatl, indigenous communities used to grow immense varieties of flowers, corn and vegetables. Together with the different types of vessels, this environment constituted a wonderful place to thrive in Prehispanic Mexico.

The construction techniques of the chinampas are in fact unique in the world. First, they would insert wooden poles into the ground, every 1.5 meters, long enough they could extend over the lake surface for 50 cm. They would then wrap the space with a reed mesh, or chinamil   in order to contain the soil. Then, they would take soil from the bottom of the lake, and stack it into different layers of organic soil and sludge until reached the desired height. Each layer is flattened on the terrain and left to dry for 2 weeks. Once it’s ready, Ahuejotetrees are planted every 40 steps along the periphery of the chinampa which also contributes to maintaining the stability of the soil. These floating gardens are usually 10 meters wide by 20 meters long with a separation of around 3 meters, which allows for the vessels to pass along the narrow canals, irrigate the crops if necessary and carry the produce directly from the field into the boat for faster transportation.

The combination of sludge from the swampy lake, which includes lacustrine and volcanic sediments like basalt and andesite, together with fresh water from the Xochimilco lake, and of course the perfectly stable climate of the place, together contributed to an amazingly efficient farming land, producing up to seven harvests per year, instead of the usual two. Xochimilco’s chinampasdesign demonstrate how the addition of energies, both human and non-human, contribute to an environmental equilibrium of the site.

The search for balance can, in fact, be found in many different layers of this system. The Milpa for example, known as Three Sisters system in North America, also the basis of the Mesoamerican diet, is based on a companion species system for corn, that includes beans, squash, as well as tomato and chili. They are usually grown together mainly because they maintain a balanced and healthy soil for future plantations. It is a great example of mutualism between different living beings. Maize is the tallest and strongest plant of the triad and requires large quantities of nitrogen in order to grow. The bean plant is grown a couple of weeks after corn in order to allow the bean to climb around the corn, and through its roots, it fixates nitrogen into the soil facilitating the growth of its bigger companion. At the same time, squash, as the creeper plant, covers the surroundings to protect the soil from eroding or drying. The covering leaves act as mulch, maintaining humidity in the soil and contributing to its companions’ survival. Milpa collaborative network is only a partial idea of what this food web signifies. Underground, The Soil food Web18 describes the fundamental existence of various living beings in the network like bacteria, protozoa, fungi, nematodes, arthropods, animals and birds, each having a specific duty to preserve life and balance. Likewise, it demonstrates how equally important both the upper and the underworld are for the preservation of the cycle of food, considering its stage of life and also its stage of death, as it transforms into organic matter and returns its nutrients into the ground.

The amount of energy exchanged during the corn cycle of growth is absolutely extraordinary. The nutrients of the soil travel through various organisms cooperating in order to maintain life in the system. The seed, on its side, takes the energy from the nutrients and from water and starlight to begin its transformation process. As the cycle moves forward and the plant organisms keep growing, the leaves take a bigger part in the story as they catch energy from the air, in the form of carbon dioxide and nitrogen, which dissipates all the way down until its roots, back into the soil, and finally gives back some part up into the atmosphere. As the milpa cycle arrives to its end, kernels start appearing in the plant as a resilience strategy for the survival of the species. The corn starts forming the seeds, and the flowers to focus its energy in the creation and dissipation of the genes for future generations. This is the beginning of the stage of death for the plant. Corn, is indeed a very special species of nature, as in order to maintain its presence on Earth, it needs human energy for domestication and reproduction. Milpa was indeed a great example of mutualism on this more than human world. Seeds hold the energy of the past and of the future together enclosed in an unbelievably strong container. When put into lacustrine sludge, they release their saved energy into the soil in the form of roots that become the agents of exchange between the underground and the upper worlds of nutrients.

These 12 x 20 m. rectangles, when analysed in plan, all follow a specific grid. That is rotated exactly 15.28º NE. Curiously enough, this orientation follows the one of an extremely important archeological site, 48 km north of Xochimilco, Teotihuacán. A city that existed since the first century after Crist, until it’s mysterious collapse around the year 650 CE. Teotihuacán is constructed with two main monuments, the Sun Pyramid and the Moon Pyramid, connected by a 4 km long road called the Calzada de los Muertos. This road of the Death, just like the Xochimilco chinampas, is also oriented 15.28º NE and the sun sets exactly in front of the Sun Pyramid on two different days of the year, April 29th and August 13th. Same dates in which it is possible to observe Venus appearance in the sky as the morning star, and subsequently as the evening star.

Like for many cultures, Venus was a special star for Mesoamerican civilizations. It is the second planet closer to the Sun, after Mercury. Venus moves faster than Earth, it completes 13 turns in 8 Earth years. This is the cycle of Venus observed form Earth. For Venus,  one orbit around the Sun equals 225 Earth days but only 260 days of being visible from this side. The same time span between august 13th and April 29th. The ratio between 365 and 260 equals 1.42 or the square root of 2, and is in fact the same ratio between the external circle of the Aztec calendar and the internal one. Because as a matter of fact, Prehispanic cultures lived their lives with two different calendars, the solar, and the Synodic or agricultural calendar. They understood that life on Earth can contain different times and thus different cycles, living in mutuality in the same more than human land.

Teotihuacán people, as well as Xochimilcas and the whole Mesoamerican cultures, looked at the energies of the sky to measure time and energy on earth; because the appearance of Venus as the evening star in the sky is also the beginning of the rainy season in the Basin of Mexico, which was the queue for the people of the Valley to start planting the corn that fed them, and begin Milpa’s cycle of growth. In this big network of overlapping rhythms, some times coincide and some don’t. But in the end, they all exist in the same space, with organisms and cycles, of various scales, that support each other to allow for the equilibrium of the whole system.

Today the story is different, the remaining fresh water from the lake is being extracted from the chinampas to supply potable water to a city of more than 20 million. Instead, the Conservation area of Xochimilco receives treated water from the sewage of the same population, treated in the Cerro de la Estrella treatment plant. Sometimes, the terrain subsides and loses all its water, for unknown reasons, and human energy intercepts to return it to its modern equilibrium. It is also a place full of cultural exchange, that remains as part of the inhabitant’s identity and long-lost memory of what the city of Tenochtitlán represented for the Basin of Mexico.

Rubio, Maya, Figueroa, Fernanda, Zambrano, Luis, , Dissonant Views of Socioecological Problems: Local Perspectives and Conservation Policies in Xochimilco, Mexico, Department of Zoology, Institute of Biology, National Autonomous University of Mexico, Mexico City, Mexico, Department of Ecology and Natural Resources, Faculty of Sciences, National Autonomous University of Mexico, Mexico City, Mexico, Conservation and Society 18(3): 207-219, 2020

Peralta de Legarreta, Alberto, Manual para comprender y construir una Trajinera, http://www.alberto-peralta.com/objetariocdmex/manual_trajineras.html#:~:text=Le%20siguen%20la%20trajinera%20Grande,brazos%E2%80%9D%20de%20aproximadamente%2065%20cm.&text=La%20trajinera%20tiene%20tres%20partes,el%20Fondo%20y%20las%20Cabeceras

Espíndola, José Pablo, ¿Qué causó la grieta de Xochimilco?, 26/01/2017, El Universal, Ciudad de México, https://www.eluniversal.com.mx/articulo/ciencia-y-salud/ciencia/2017/01/26/por-que-se-genero-la-grieta-de-xochimilco

Calendarios Mexicas, https://www.wikiwand.com/es/Calendarios_mexicas

Lynn Margulis, Symbiosis as a Source of Evolutionary Innovation, MIT Press, 1991

Scott F. Gilbert, Jan Sapp, Alfred I. Tauer, “A Symbiotic View of Life: We have never been individuals”, The Quarterly Review of Biology, Vol. 87, No. 4 (December 2012), pp. 325-341.

Elaine Ingham’s Soil Food Web, n.d.

Adriana David

Adriana David is an architect with honors from the Universidad Iberoamericana, she holds a master's degree from Harvard University GSD in the Art Design and the Public Domain program, as well as in Scenic Design from IED Madrid.

Her work lies at the intersection of architecture and the natural world. Her research focuses particularly on Food Sovereignty as a mechanism to restore the broken bond between human beings and nature. She is continuously exploring multidisciplinary approaches to engage with environmental health through public space. Her recent projects include LIMBO urban seedbanks, a choreography for a more-than human world, a performance dinner on the impact of today’s impact of agribusiness on food and a set of tools to achieve Harvard’s Food Sovereignty for the future.

She is the founder of DOMA, a spatial design studio based in Mexico City working at the intersection between architecture, ecology and public space. Her practice varies considerably in scale. She has collaborated with the Papalote Children’s Museum, the Mexican Housing Commission, the Ministry of Agrarian, Land, and Urban Development and the Ministry of Culture as Architecture jury member on several occasions.

Her work has been presented in venues such as the 2021 Venice Architecture Biennale, the Tamayo Museum, the Zapopan Art Museum, and Harvard's Kirkland Gallery. He has also participated as a speaker in forums such as the What Design Can Do Mexico 2025 design meeting and SEED COLLECTIVE 2024. She has published in media outlets such as DOMUS magazine, the Harvard Urban Review, and the book Desire Lines: Resistance and Rediscovery, published by the University of the Arts Helsinki.

She has collaborated as a researcher and teacher at Harvard GSD, is a professor at the CENTRO design school and the Universidad Iberoamericana, and is currently part of the National System of Art Creators 2025- 2028.

Throughout her career, Adriana David has demonstrated a constant commitment to design as a tool for social, environmental, and cultural transformation. Her work explores new ways of inhabiting, sowing, and caring for local territories through Mexican agrobiodiversity.

︎ adriana@doma.mx
︎ @adrianadom
︎ @domamx
︎ www.doma.mx