Academic history, domains and distribution of the hot-cold system in Mexico.

BACKGROUND: The hot-cold classification system for things and concepts is widely used by many human groups in Mexico. We conducted a comprehensive review to understand the history, themes, and distribution of this system. METHODS: We analyzed publications based on field work in Mexico, considering publication date, research approach, study depth, and conceptual domains. We identified the ethnic groups that use the system and the places where they live. A map illustrates the geographic and cultural distribution of the system. RESULTS: The hot-cold system has been documented in 101 academic publications spanning almost a century, particularly for traditional medicine and food. Initially dominated by anthropological studies, ethnobotanists have increasingly contributed to the research. The hot-cold system is utilized by at least 56 indigenous ethnic groups (81% of the total) and mestizos (whose primary or sole language is Spanish) across most of Mexico. DISCUSSION: Anthropologists laid the foundation for understanding the hot-cold system, on which current ethnobotany builds. However, there are still knowledge gaps, for example on some domains (human beings, landscape) and on patterns by regions or linguistic families. The geographic and cultural distribution presented here is approximate, as group ethnicity is imprecise. CONCLUSIONS: The hot-cold system is widely applied in Mexico, although some variations exist. Further exploration of understudied domains, and variations between ethnic groups and regions, would contribute to a comprehensive explanation of this interconnected worldview.

Climate and categories: Two key elements for understanding the Mesoamerican hot-cold classification of illnesses and medicinal plants.

ETHNOPHARMACOLOGICAL RELEVANCE: The concepts of health and illness, and their causes, are fundamental for understanding medicinal plant choice and use by traditional people. The hot-cold system is widespread in Mesoamerican traditional medicine and guides many therapeutic decisions. AIM OF THE STUDY: This study explores a hypothesis that climate influences the hot-cold classification of illnesses and medicinal plants, and the perception of hazard of illnesses. In addition, we examine the classification categories within the system used in different regions of Mexico. MATERIALS AND METHODS: Studies from Mexico with quantitative and qualitative data on the hot-cold properties of medicinal plants and ailments were reviewed. The information was organized and then related to the climate type of the study areas. RESULTS: In temperate climates, most diseases were considered cold, and hot medicinal plants were dominant. Conversely, in warm-tropical climates, hot diseases dominated, and the majority of medicinal plants were cold; however, this evidence was weaker. The perception of hazard was congruent with the number of illnesses for temperate climates. There were additional classification categories within the hot-cold system for diseases and medicinal plants, and they were expressed in different terms in Spanish, English, and indigenous languages. Although similar terms and categories were used in the classification of diseases and medicinal plants, they can differ conceptually and vary between places and cultures. Publications are sometimes unclear if the terms used are emic or etic. The basic principle of using plants with the opposite property of the disease does not always apply strictly. CONCLUSIONS: Climate appears to influence the hot-cold classification of diseases and medicinal plants in Mexico, and the system is not strictly dual. Improved knowledge of the hot-cold system is necessary to understand Mesoamerican medicinal plant use and culture.

This plant treats that illness? The hot-cold system and therapeutic procedures mediate medicinal plant use in San Miguel Tulancingo, Oaxaca, Mexico.

ETHNOPHARMACOLOGICAL RELEVANCE: Understanding the reasoning behind the choice of medicinal plants is relevant for both pharmacological and ethnobotanical quantitative studies. In this study, we analyze how the traditional medical system influences the choice of medicinal plants in a Mexican indigenous population. MATERIALS AND METHODS: The study area was San Miguel Tulancingo, Oaxaca, Mexico, and the studied people the Rru ngigua (or Chocholtecs), an Otomangue group with only a few hundred speakers remaining. Through in-depth and repeated interviews of four traditional healers and ethnobotanical collections, we identified, described and classified the medicinal plants, the nosological units, the therapeutic procedures and the reasoning behind medicinal plant and treatment choice. RESULTS: The hot-cold system, which considers illness to be a result of humoral imbalance, strongly influences treatment choice. "Hot" plants are used mainly to treat "cold" diseases, and vice versa. With some variation, plants are selected mainly for this hot-or-cold property, and the specific plant species is often not very relevant. In addition, many plants are associated with specific healing procedures, such as sweat baths. The procedures, in turn, may be used to treat various diseases. CONCLUSIONS: The study shows that the relationship between medicinal plants and treated diseases is complex and indirect in most cases. It is strongly influenced by the hot-cold concept and by therapeutic procedures.