Conservation Biology

Wednesday, August 16, 2006


Without going into too much detail about the general history of the Aztecs, I have tried to incorporate as much relevant material regarding the reliance and strain on natural resources as well as the affects of their religion and culture on others of the time as well as our more-modern time.

The name “Aztec” today refers to the collection of all those people who are linked to the founders of modern Mexico, those once migrant tribes from Mesoamerica, through the past associations of trade, religion and language [1]. The ancient Aztecs were an extremely successful civilisation, founding an empire in the 15th century, which was second only in size to that of the Incas in Peru. Apart from the imperial style administration, Aztec society was highly advanced and specialised specifically in terms of an agricultural economy. Agriculture played and important yet organically-adjusted part of everyday life, allowing for a relatively harmonious existence with nature [1]. The Aztec empire formed in the Valley of Mexico as a result of peace among faction states coming together to form an alliance of the three main states: Tenochtitlan, Texcoco, and Tlacopan [12].

The Aztecs believed that society itself was an integral part of the cosmos, which formed part of their intellectual and also religious beliefs. The Aztecs were acutely aware of their interdependence with nature, but also with that of humanity [1].

To look at the affects that the Aztecs had on their environment we need to delve into the history of their success not only in agriculture, but also trade and mining, as the depiction of everyday life and religious significance, which is relevant, and an integral part of life, is symbolised most expressively within their works of art.

The “Religious” footprint:

Religion was an extremely important part of everyday life, with literally hundreds of gods being worshipped that were associated with one or more everyday activity or natural occurance or aspect of nature such as the elements [1] of Earth, Fire, Water and Air. Some examples of their gods with associations with nature include ([1]):

“Ehecatl,” the god of wind.
“Quetzalcoatl,” the god of the air.
“Huitzilopochtli,” the god of the sun and war.
“Tonatiuh,” the god of the sun.
“Centeotl,” and “Xilonen,” the gods of corn.
“Tlaloc,” the god of rain.
“Xipe Totec,” the god of Spring.
“Xiuhtecuhtle,” the god of fire.

What is interesting is the association of fire with time, and time played an integral part of Aztec society. The “New Fire Ceremony” is one of the only Aztec rituals, which is documented both in historical documents and archaeological evidence [9]. The cosmos, time and fire played a significant role within the Aztec religion, and the “New Fire Ceremony” was a ritual enforced by the Aztecs as part of its imperial programme of legitimising control over scattered groups of neighbouring tribes [9].

Aztec religion is often associated with extravagant costumes and headdresses of colourful plumes of exotic-looking feathers. In an article by Frances Berdan (2004), “Circulation of Feathers in Mesoamerica,” published in “Feather Creations. Materials, Production and Circulation.” New York, Hispanic Society-Institute of Fine Arts, it is indicated that feathers were not only culturally significant, but the demand for different feathers from different birds from the home-range of the Aztecs was relatively large because not only were feathers used in religious displays as adornments for the gods, but also made up additions to textiles and shields and military costumes. Feathers became an asset of trade and changed hands many times through market places, making them high in demand in large quantities. Feathers ultimately became a precious commodity for the growing number of consumers, which included trade between tribes.

Feathers also became what are known as tribute items and sent “as tribute” both raw and as completed forms of art as forms of annual payment in accordance with the written law of the time. This law was spelled out in glyphs from the Codex Mendoza, where specific towns were indicated to give a specific tribute to the Aztec ruler [3]. There are 235 recorded species of bird in the Chiapas area in Mexico, of which 75.7% are permanent residents [4] and 464 bird species in the Chimalapas region, [5] however, it is unknown exactly how many species were exploited for their feathers [2].

So what impact did this have on the local bird populations?

Well, although there is some confusion regarding the specific species of birds used for feathers because of the differences in dialects where certain words meant different things in the Aztec world, according to Frances Berdan (2004), the following birds could have been used: For the red feathers, Scarlet macaw, or Roseate spoonbill, and the green feathers from either the Green (Pacific) Parakeet, or the Mexican Trogon. Trogons are known to be sexually dimorphic and the male bird’s plumage is different in colour to that of the female [13]. It is therefore possible that exploitation of one sex, primarily the male bird, for more colourful feathers, could have led to an impact on the breeding success of these birds at that time.

Apart from the extravagant use of feathers, the more morbid side of Aztec religion included ritual human sacrifices. A theory exists which suggests the reasons for such human sacrifices called “The Population Pressure Theory of Social Evolution,” which states that population pressure on natural resources could well be a major determining factor in the regularities or perceived irregularities in human socio-cultural evolution [6,8]. It is also theorised that the intensification of agriculture is directly related to population pressure on natural resources, and, population pressure actually results eventually in the evolution of pre-industry and politics [6].

So significant was the need for human sacrifice that the Aztecs even resorted to military and war-style human sacrifices in the form of an institution known as “Xochiyaoyotl” or “Flowery wars,” to fulfil the requirement [7]. During these Flower wars, two states agree to battle each other, but not to defeat the opposing contender, but to obtain the mortality requirement [7]. Interestingly, it may have been these ritual and religious wars, which gave the Aztecs the physical military practice, which affectively created one of the most experienced civilisations in war, of their time [7]. What is possibly also a suggestion is that with the elimination of suitable herbivorous animals from the region as a result of a growing population, could sacrifices not be seen as a cover for a more sinister function of survival, to reduce the population, or even to supplement the lack of meat-protein through canabbalism?

What impact did Aztec religion have on Christianity, and Christianity on Aztec religion?

I found a most interesting passage in the paper by Alice B. Kehoe (1979) where the author explains that the relatively recent depiction and use of the “Sacred Heart” of Jesus, and therefore devotion to this symbol, depicted sometimes by a realistically portrayed human heart (sometimes in flames), was a late development in Roman Catholicism. This depiction is thought to be the result of the interest and focus of Catholic scholars working with the missionaries with the Aztecs, who had used this symbol in their religion. The paper suggests that the adoption of this symbol into Roman Catholicism may be as a result of either co-incidence, or what is known today as “stimulus diffusion,” where acculturation occurs, i.e., the influence of one society or culture on another, as a result of continuous face-to face contact. It is suggested that certain aspects of one culture can be assimilated into another quite unconsciously, and the theory of “stimulus diffusion” is therefore an elusive one [10]. Even more interesting is the suggestion by Ruth Shonle (1924), that although it was originally thought that preliterate people (in the eyes of the missionaries) would happily exchange their religious beliefs for Christianity, in fact what took place most often was a fusion of both Christianity and the native religion into a new third type of religion [11].

So, if religion is the pivot by which everyday life functions, and, though seemingly rigid and powerful in its role in the pathway of certain ecological impacts by associated practices, how then does a change in religion, or a complete breakdown in religion not only change the culture of the people, but the way they go about their everyday lives? Would this be a negative or a positive change to the ecological relationship that the people would have with their environment, and did the exploitation of religion for purposes of trade have an impact on the ecological footprint?

In 1519, Spanish rule led by Hernán Cortéz took over the native town of Jalcomulco after an overthrow of the native Aztec overlords by the Spanish together with disgruntled native subjects. Prior to the arrival of the Spanish, the tribute system as mentioned above formed an integral part of the society in the town of Jalcomulco, but with the arrival of Hernán Cortéz and Roman Catholicism, the local population submitted to Christianity and the tithing system. A significant amount of wealth was built in this way for the Catholic Church, and the local people were labelled as subjects of the Spanish crown, which incidentally was administered almost entirely by the Church [12]. Money generated as part of the tithing system became part of a lending system for the haciendas of the region [12]. Haciendas were large landed estates owned primarily by the elite (Spanish) who also subsequently ran the local government. The native people of Jalcomulco would have been allowed to work on these estates to earn a wage, however, the owners of these estates often bound them to working the lands by keeping them in a constant situation of debt, a situation probably uncommon to these people, who were ultimately treated as slaves [12]. Religion then most certainly does play an important role in the economics and impressions left by a changing ecological footprint.

Although religion was the primary motivation for everyday aspects of life for the Aztecs, it was agriculture that was the principle activity of the people [14]. Farming was necessary to sustain the growing population of the Aztecs, as suggested by “The Population Pressure Theory of Social Evolution.” Apart from terraced agricultural sites on hills, which included irrigation and the use of fertiliser, the surrounding lands where the Aztecs lived were just not fertile enough to sustain large-scale continuous agriculture, so they invented what are known as Chinampas, or floating gardens built in the swamps [14]. Chinampas are still in use today as small home-gardens in the Mexico valley, and are unique in that they are thought to be the first type of hydroponics used in civilisation, and are completely nutrient recycle-orientated systems designed not only as space savers, but as renewable sources for food production.

To make the Chinampas, stakes or tree trunks were placed into the soil of the shallow lakes or swamps. Once they had taken root and started growing they gave stability for growing crops. These Chinampas were in fact artificial islands measuring about 30 meters long by 2.5m [15], with an area of 75m². The stakes or tree trunks were fenced into the general shape of the Chinampa using Wattle, which was then layered with mud and lake-bottom sediments, which are very fertile [15]. The mounds were added to until the actual level of these islands was raised above the water level [15]. Species of Willow were planted at each corner for strength and to give a certain amount of shade and wind protection to the crops being growth on the Chinampa, and there were channels created between the Chinampas just wide enough for canoes to fit between [15]. Water was used directly from the surrounding channels. Crops grown on the Chinampas included beans, squash, chilies, maize, tomatoes, and the herb known as amaranth [15]. Tomatoes were unknown to Europe until the 16th century, and its is this cultivation of tomatoes which led to the introduction and spread of the tomato around the world today [23]. Also, maize was often used in the form of popcorn strung together to decorate some of the Aztec gods…so next time you eat popcorn, give a thought to where it originated!

The successful growing population of the capital city of the Aztec empire, Tenochtitlan was thought to have been as a result of the Chinampa farms, which encircled the city [15]. The earliest Chinampas dated are from what is known as the Middle Postclassic Period, the period between the year 900 and the time of the Spanish conquests between 1521 and 1697 [16]. The Chinampas were used extensively on the lakes of Xochimilco and Chalco. Lake Xochimilco is located in the valley of Mexico and is what is known as an endorheic lake. An endorheic lake is actually a watershed from which there is no outflow of water, often forming as a closed basin [17]. Lake Xochimilco is actually a brackish lake, which makes up a series of lakes in the region, however lake Chalco is completely freshwater [17]. It may well have been slightly easier to grow crops in lake Chalco for this reason, though freshwater springs lined the lake [17] and this may well have been the source of irrigation water for the growing crops in this brackish environment.

The use of Chinampas not only provided the Aztecs with a continuous source of food, but the utilisation of such a system was environmentally friendly and the growth of food on islands gave a higher level of overall crop security and success since the majority of ground-dwelling pests could not access the crops surrounded by water [18]. It could also be argued that the Aztecs, in their success with agriculture provided enough food to sustain markets and trade, and therefore a type of economically driven society as a result, and, that the use of Chinampas can be seen as an attempt towards nature conservation since land was not cleared for farming [18].

On a different note though, the Chinampas would have had an impact on the aquatic fauna of the various lakes, so I decided to see if I could find some interesting facts to support my curiosity…

The Axolotl (Ambystoma mexicanum), a strange amphibian, which looks like a grown up tadpole, was once abundant in lake Xochimilco until the creation of the Chinampas. The Chinampas raised the base level of the lake into the useable mounds mentioned above, drastically reducing not only the water flow and movement but also the habitat of the Axolotl, which is today one of Mexico’s most threatened species and labelled as a critically endangered species on the IUCN red data list of species, with an existing population area of only 10km² [19, 22]. The Axolotl was well known to the Aztec people and held an important position in their mythology as the god who transported the dead to the afterlife [20]. In addition the Aztec also used the Axolotl as a source of food [20].

Apart from the amphibians, a small fish called the Sailfin Goodeid (Girardinichthys viviparus) from lake Xochimilco and surrounding areas, which has recently been bred for the first time in captivity [21], is part of the group of fishes known as a live-bearers, and give birth to live young. Most live-bearers require floating structures and debris as protection for their fry, without which, their population could arguably fall prey to higher predation. With the addition of the Chinampas, and therefore additional structure to hide the fry, the fish population may well have become more successful, even if the Aztecs fished for them, though there is no direct evidence of this. Conversely, if the affects of the Chinampas on the ecology of the lake system increased the dissolved nitrogen such as the Ammonia levels and Nitrates from the addition of manure to the Chinampas, and the blocking out of available sunlight to aquatic plants to break down these Nitrogen levels, the substrate could well have become more anaerobic, and therefore reducing the available dissolved oxygen content within the lake, which would have had a completely negative impact o ALL aquatic life in the lake.

Mining, apart from agriculture and religion, also played an important role in the Aztec civilisation. The discovery of the Fire Opal by the Aztecs became significantly important to the Spanish, who took the gem back to Europe with them [24]. The fire opal was given the name “Quetzalitzlipyollitli” which means “The Stone of the Bird of Paradise.” Interestingly, the fire opal was nearly forgotten after the knowledge of it dwindled through the generations of native Mexicans until 1835, when it was again remembered, putting in motion an increase in mining. Today this opal is the National Stone of Mexico [24].

In conclusion, without continuing to far into the massive footprint which the Aztecs left, or the associated reciprocal problems associated with their civilisation, I believe that the Aztecs through their innovation and will to survive, were able to overcome most of the obstacles facing their growing population. This growing population led to the founding of today’s most heavily populated city in the world, Mexico City, which is responsible for some of the worst air pollution in Central America. Could it be that the legacy of the Aztec nation still survives today through the continuous growth of the Mexican people?

Undoubtedly, through all successful civilisations and the merging of technologies and ideas passed onto progressive generations which eventually became today’s global society, the human race has been catapulted into an era of successful growth and global expansion, though the lessons of responsibility and control through the dismissal of ignorance is possibly the most urgent lesson of future success that we could possibly hope to learn. How desperate will the global situation become before we realise that it is too late?

If “The Population Pressure Theory of Social Evolution” is correct, and politics as an evolutionary result of our overall success and growth into a global society is to be believed, is it then not up to the politicians to enforce the solutions to global problems which are being raised today?

The future will most certainly be interesting, though, we may well be faced with the collapse of the human race in the larger context, which is often echoed within the disappearance of ancient civilisations…a climax and then a collapse. When will we ever learn!

David Vaughan
Senior aquarist, Quarantine
Two Oceans Aquarium
Cape Town, South Africa

Picture credits:


Mexican Trogon:


Sailfin Goodeid:


[1] [Internet] [cited 14 Aug 06] Available from:

[2] Berdan F. 2004. Circulation of Feathers in Mesoamerica. Hispanic Society-Institute of Fine Arts (no page numbers given).

[3] University of Texas. Law in Mexico Before the Conquest [Internet] [cited 14 Aug 2006 21:13] Available from:

[4] Puebla-Olivares F., Rodriguez-Ayala E., Hernández-Baños B. E., Navarro S. A. G. 2002. Staus and Conservation of the Avifauna of the Yaxchilán Natural Monument, Chiapas, México. Ornithologia Neotropical 13: 381-396.

[5] Townsend-Peterson A., Navarro-Sigüenza A. G., Hernández- Baños B. E., Escalona-Segura G., Rébon-Gallardo F., Rodriguez-Ayala E., Figueroa-Esquivel E. M., Cabrera-Garcia L. 2003. The Chimalapas Region, Oaxaca, Mexico: a high-priority region for bird conservation in Mesoamerica. Bird Conservation International 13: 227-253.

[6] Harner M. 1977. The Ecological Basis for Aztec Sacrifice. American Ethnologist 4(1) Human Ecology: 117 – 135.

[7] Hicks F. 1797. “Flowery War” in Aztec History. American Ethnologist 6(1): 87 – 92.

[8] Winkelman M. 1998. Aztec Human Sacrifice: Cross-Cultural Assessments of the Ecological Hypothesis. Ethnologist 37: (No page numbers given).

[9] Elson M. C., Smith M. E. 2002. Archaeological Deposits from the Aztec New Fire Ceremony. Ancient Mesoamerica 12: 157 – 174.

[10] Kehoe A. B. 1979. The Sacred Heart: A Case For Stimulus Diffusion. American Ethnologist 6(4): 763 – 771.

[11] Shonle R. 1924. The Christianizing Process Among Preliterate Peoples. Journal of Religion 4(3): 261 – 280.

[12] Cooper C., Finzi J., Hasbrouck J., Todd V. 2004. A Case Study of Sustainability: Jalcumulco, Veracruz. USG Centre for Sustainable Cities.

[13] Wikipedia contributors. Black-throated Trogon [Internet]. Wikipedia, The Free Encyclopedia; 2006 Jun 12, 08:59 UTC [cited 2006 Aug 15]. Available from:

[14] ThinkQuest: Aztecs: Farming and Agriculture [Internet] [cited 15 Aug 2006 22:30] Available from:

[15] Wikipedia contributors. Chinampa [Internet]. Wikipedia, The Free Encyclopedia; 2006 Aug 14, 07:32 UTC [cited 2006 Aug 16]. Available from:

[16] Wikipedia contributors. Mesoamerican chronology [Internet]. Wikipedia, The Free Encyclopedia; 2006 Aug 11, 10:30 UTC [cited 2006 Aug 16]. Available from:

[17] Wikipedia contributors. Endorheic [Internet]. Wikipedia, The Free Encyclopedia; 2006 Aug 16, 08:30 UTC [cited 2006 Aug 16]. Available from:

[18] Altieri M. A. Agroecology In Action. University of Berkley [Internet] [cited 16 Aug 2006 11:12] Available from:

[19] Griffiths R. A., Bride I. G. 2005. Newsletter of the Declining Amphibian Populations Task Force. Froglog 67: 1 – 4.

[20] Wikipedia contributors. Xolotl [Internet]. Wikipedia, The Free Encyclopedia; 2006 Aug 13, 23:41 UTC [cited 2006 Aug 16]. Available from:

[21] Serva R. Breeding the Sailfin Goodeid - Girardinichthis viviparous. 2001. [Internet] [cited 16 Aug 2006: 12:04] Available from:

[22] Global Amphibian Assessment. [Internet] [cited 16 Aug 2006: 12:13] Available from:

[23] Veggie Cage: Tomato history. [Internet] [cited 16 August 2006: 12:34] Available from:

[24] Los Cabos Guide: The Fire Opal [Internet] [cited 16 Aug 2006: 13:08] Available from:


Since David has asked for more details on where the animals and plants came from that were domesticated, here is some info from the paper by Mannion (1999). (Due to lack of time, I have copied and pasted the info… hope this is not too illegal!!)

“The ancestors of the domesticated sheep, goat, cattle and pig are the mouflon, bezoar goat, auroch and wild pig respectively. In the case of domesticated cattle, there is biomolecular evidence based on the analysis of the mitochondrial deoxyribonucleic acid (mDNA) sequences in the mitochondria of modern species in Africa, Europe and India to indicate that there were at least two centres of domestication (Bradley et al., 1996). One of these was probably southwest Asia whilst the other was in India.” (Mannion 1999, p47)


Bradley DG, MacHugh, DE, Cunningham, P and Loftus RT. 1996: Mitochondrial diversity and the origins of African and European cattle. Proceedings of the National Academy of Sciences of the United States of America 93: 5131–5135.

Evans LT. 1993. Crop evolution, adaptation and yield. Cambridge: Cambridge University

Mannion AM. 1995. Agriculture and environmental change. Temporal and spatial dimensions. Chichester: Wiley.

Mannion AM. 1999. Domestication and the origins of agriculture: an appraisal. Progress in Physical Geography 23(1):37–56

Normile D. 1997.Yangtze seen as earliest rice site. Science 275: 309 (this report concerns ecent research results presented to the nternational Symposium on Agriculture and ivilization, Nara, Japan, 13–14 December1996).