The Aztec emphasis on ritualized human sacrifice and the sheer quantities of victims involved have long been recognized as apparent extremes of cultural behavior in the world ethnographic record.  Michael Harner, in his 1977 publication The Ecological Basis for Aztec Sacrifice, proposed an ecological and evolutionary theory to explain why the peculiar development of the Aztec sacrificial complex was a natural consequence of concrete subsistence problems that were distinctive to Mesoamerica – especially to Central Mexico (Harner 1977:117).  Harner used a population pressure model to present an understanding of the regularities of socio-cultural evolution – an explanation of unusual cultural developments.  Here he focused on the cultural distinctiveness of Mesoamerica especially as exemplified by the ritual of human sacrifice among the Aztecs (1977:117). 

Harner stated that among state societies in the ethnological record, the Aztecs sacrificed a total of 20,000 victims annually – an estimate he made based on the figures of other scholars.  His reasons for this seem logical at first.  He noted in this publication that the extinction of big-game mammals by the end of the European Paleolithic was the first outstanding evidence of the shift to using human flesh to acquire the amino acids needed for nutritional well-being.  He also notes that the seriousness of population pressures during the time of the Aztecs was a major factor in the increased efficiency of sacrifice and subsequent cannibalism (1977:118).  Population pressure was discussed by many researchers prior to Harner’s article (e.g., Vaillant 1966:136-137).  Moreover sacrifice and cannibalism – to Harner – were one in the same and the thesis of his article was that cannibalism was disguised as ritualistic sacrifice and was the natural consequence of the insignificant amount of meat available as well as population pressures. 

Nutritionally speaking as noted above, Harner claimed that due to a scarcity of meat in the Aztec diet, and the limited amino acids/fats available in the consumption of maize and beans separate from each other (due to either famine or poor harvests during dry years), they relied on human flesh to augment their intake of the necessary nutrients.  They theoretically could get the necessary eight essential amino acids from their maize and bean crops, but this wasn’t always available so they took different avenues to adjust for the lacking nutrients in their diets (1977:127).

If Aztec cannibalism was a response to growing population pressure, one would expect it to increase in frequency through time.  And though there is a numerical rise in the capture and sacrifice of human victims, there is no certainty that cannibalism is connected to either.  He proposed that approximately one percent (15-20,000) of the population of Mexico were eaten on an annual basis.  Though the point of his paper was to explain the extremity of the Aztec sacrificial complex, Harner places a large amount of influence on cannibalistic contributions to the diet of the Aztecs.  As is often the case in human societies, the rules for Aztec cannibalism were probably forged under the extreme conditions of scarce food situations (1977:126,129).  We see that in the Aztec case then, an extreme development, under conditions of environmental circumscription and very high population pressure, “cannibalism was the only possible solution” (1977:132).

Most of the criticism of Harner’s work lay within the fact that he based his figure of 20,000 annual sacrifices on the statements of Spanish travelers of the 1500s.  Moreover, Harner states that his most reliable sources were three conquistadores from the Spanish conquest in YEAR.  Beyond the crude number of sacrifices each year was the question of what happened to the bodies post-sacrifice.  The evidence of cannibalism in Aztec society seemed either largely ignored or covered up for some reason (1977:119).  His Spanish sources made a point to uncover these “truths” about Aztec customs.  Bernal Díaz for example reported:

“When [the Spaniards] came to these villages, [they] found that they had been deserted on that very day, and they saw the bodies of men and boys who had been sacrificed, the walls and alters all splashed with blood, and the victims’ hearts laid out before the idols.  He also found the stones on which their breasts had been opened to tear out their hearts.  [They] told us that most of the bodies were without arms and legs, and that some Indians had told [them] that these had been carried off to be eaten.”

This ideology was therefore easy to believe as it was only one of over a thousand recorded quotes of Spaniards during the conquests.  The Spanish accounts of what happened did not necessarily measure up though.  Relatively few of them were first-hand accounts though, even if the bodies were seen, the stories were still only told by the indigenous persons.  Not one soldier of the Spanish Conquest saw with his own eyes a person being eaten.  This is a point that Harner fails to mention.  His article is strewn with; rather it is full of stories retelling the horrors of what seemed to be cannibalism in Mesoamerica. 

While some sacrificial victims were not eaten (children and diseased persons), it seems that the overwhelming majority of the captives appear to have been consumed.  Captives were kept in wooden cages until they were sacrificed by the priests at the temple-pyramids.  “Most of the sacrifices involved tearing out the heart, offering it to the sun and, with some blood, also to the idols” (1977:120).  The body of the victim was then tumbled down the steps for the captor of the victim to cut up and distribute as he saw fit. 

The works of Father Bernardino de Sahagún are probably the most reliable and thorough source on the subject of Aztec cannibalism and Harner quotes him extensively through the latter half of his article. Using Aztec nobles as informants, Sahagún transcribed their written or dictated information in Nahuatl as a series of books (1951, 1954 and 1970).  There are limitations to only obtaining the upper-class insiders’ view of Aztec culture though.  Certain aspects of their behavior, such as cannibalism, probably were too routine an aftermath of sacrifice to deserve comment from the nobility.  Besides, there is no way to tell whether these stories were adapted for the “civilized” public, or how accurate the stories were, as they were told by the nobles.  It is easy to tell a tale to entice one’s listeners – any anthropologist familiar with ethnographic work understands this.  Sahagún’s narrators probably took the anthropophagic aspect for granted (1977:124-125).  Excerpts used in Harner’s article from Sahagún’s books serve to illustrate some of the details of Aztec cannibalism and demonstrate a consistency with the accounts of Cortés and other members from his expedition.  Harner also quotes Durán, who on the other hand, motioned that the flesh of sacrificial captives was considered “leftovers” and was returned to the captor as a reward for having fed the deity.

Harner does not attribute to the Aztecs a maniacal obsession with blood and torture, but strongly adheres to the notions that the basic causality of cannibalism was the cultural necessity to control population size and enhance diet. 

Michael Harner is an anthropologist who has survived his past publications, though they were ridden with what were seen, to many, as inaccurate and uneducated theory practice.  After his hiccup with Aztec cannibalism, Harner went on to teach at Columbia, Yale, the University of California at Berkeley, and at the Graduate Faculty of the New School for Social Research in New York, where he was chairman of the Department of Anthropology.  He has since devoted most of his life’s efforts to the study of shamanism.  Harner has not only practiced shamanism and shamanic healing since 1961 and pioneered their return to contemporary life, but he is also the Founder of The Foundation for Shamanic Studies, a public non-profit educational organization, in Mill Valley, California.  He has been involved with and taught shamanic methods since the early 1970s.  I would venture to say he has done quite well for himself.