In 1977 Michael Harner suggested that the Aztecs might have practiced cannibalism to obtain animal proteins. A year later, Bernard R. Ortiz de Montellano objected that the Aztecs could obtain all the required aminoacids from vegetable sources, and that their cannibalism was simply a thanksgiving ritual, because its occurrence generally coincided the maize harvest.
But at about the same time other researchers showed that maize consumption could provoke brain serotonin deficiency, which, in turn, could provoke some neurobehavioral after-effects, such as the tendency towards aggressive behavior or religious/ideological fanaticism.
In this study we attempt to show that a maize diet may cause serotonin deficiency and that this could explain cannibalism and other peculiarities of Aztec culture. The conclusions reached in this study are consistent. with past and recent evidence of cannibalism among the Anasazi, a people that was similarly heavily dependent on maize for their nourishment. More broadly, our findings indicate a probable alimentary background for aggressive or fanatical behavior in populations heavily dependent on foods that can lower brain serotonin.
Key Words: serotonin; trp/LNAAs ratio; aggression; fanaticism; maize; Aztecs.
Human Sacrifices among the Aztecs
The Aztec human sacrifice/cannibalism complex has been studied from various viewpoints, such as the religious, the social, the economic and the ecological, often in contrast to the exclusion of one another. But in our understanding of religious studies, these various interpretations are not necessarily mutually exclusive since - considering that they concern various levels of research - they can be complementary. We think, really, that religious phenomena, showing numerous aspects, may be studied at various levels: a first research level may regard the biological bases, neurological or ethological, of religious thought (Mandell 1980, Gazzaniga 1985, Burkert 1996, Ernandes and Giammanco 1998); a second level, phenomenologic-structural, the subordinate relationship of human beings to divine beings, the idea that the sacrifice is the main way to communicate with them (Hubert and Mauss 1898, van der Leew 1933, Widengren 1969, Burkert 1983, Carrasco 1995); a third, the relationships between social structures and peculiar shapes of credence and rituals (Durkheim 1912, and the sociological school); a fourth, the economic-ecological one, the material goods used for religious rituals (Firth 1971, Harris 1977, and cultural materialists; Winkelman 1998): goods for sacrifices are of course directed to gods, but they are then usually eaten by human beings. These four approaches can coexist and interact synchronically, and a fifth one may be added, the historical or diachronic aspect. Obviously, for a given religion, results of studies carried out on one level must be coherent with the results obtained for other levels, since a comprehensive study must be non-contradictory. Till now the tendency to favor a particular type of study in exclusion of any other has prevailed (Pals 1996). If this was reasonable in the past, as these various approaches were discovered little by little, it is less excusable now.
In this work we examine Aztec religion starting with the cultural materialistic and the neuro-biological aspect, which has been little studied as yet, while bearing in mind the other viewpoints with the aim of preparing the way for a multilevel synthesis.
In 1977 Harner suggested the Aztecs might have practiced cannibalism to obtain proteins containing all aminoacids in the proportions required by humans. In fact, Aztecs lacked herbivorous animals as a protein source. According to Harner, ancient hunters had completely killed off the big herbivores in the Mesoamerican area, and small game hunting did not meet the needs of the growing population. "In terms of carbohydrate production, this challenge was usually met by chinampa development and other forms of agricultural intensification; but domesticated animal production was limited by the lack of a suitable herbivore. …