Paleopathology of the PreColumbian People of Central Mexico
University of Houston
The Basin of Mexico, the center of the modern day Republic of Mexico, is a core area of one of a
handful of regions of the world where complex cultures seem to have arisen from internal social and
historical processes alone and not as a result of imposition or stimulus from other regions. The Basin
was where the great Pre-Columbian civilizations of Teotihuacan and the Aztecs developed. Here, human
settlement was encouraged by the rich flora and fauna of this high intermontane valley (2,000 meters
above sea level). Agriculture slowly evolved, and along with it came larger and more complex societies.
By the Classic period, around 300 A.D., the first urban complex society had appeared, that of
Teotihuacan, which because of its size and splendor influenced much of Mesoamerica. After the fall of
Teotihuacan, the Basin saw the appearance of other similarly complex societies, culminating in the Aztec,
who ruled an empire from the island city, Tenochtitlan. This Postclassic florescence was interrupted by
the Spanish Conquest in 1521, and for the next three centuries, the Basin of Mexico was the site of one
of the most important of Spain's American colonies. Thanks to a temperate climate and the presence of
large lakes, some of the highest population densities in the Ancient Americas were attained.
Despite the amount of information that we have from these ancient societies, whether from small or
grand monumental sites, our knowledge about their inhabitants is less developed. One approach is to
study the skeletons. The work to be presented here is the result of collaboration with Mexican
colleagues, most especially with Dr. Lourdes Marquez, without whom much of the following discussion
would not be possible.
Usually the past is thought of in one of two ways: either as a place where humans had fewer problems,
and a simpler, healthier life; or where humans were bedeviled by health problems, high mortality rates,
and reduced life expectancy. However, the study of health and disease is necessarily tied to how human
populations adapt to different physical environments, as well as to different modes of subsistence and
social organization. Health problems seen today in the Basin of Mexico are due to high population
density, air pollution, water contamination, and economic and social problems associated with a megapolis
whose growth has outpaced the ability of government, private organizations and citizens to meet their own
needs. It is possible to ask if the health of the ancient inhabitants of this same region had better or
worse living conditions and health, and which of their problems were similar with similar causes.
The results obtained from the analysis of paleopathological skeletal indicators of health, nutrition,
and lifeways of the different populations in and around the Basin show how the cultural development and
historical situations affected people. The skeletal samples included in this study represent early
agricultural villages, urban centers of powerful states, and a city peripheral to but part of other
regional powers. Are there relationships between social complexity, health, and population density? Are
there trends in health through time during the Pre-Columbian era? Although it is not possible here, with
the generally small skeletal samples available, to fully investigate the implications of these questions,
it is possible to contrast living in the more urban and complex settlements with smaller, less dense
ones. As the urban, complex settlements become more common through time, it is possible to investigate
whether health become better or worse through time in such places.
Methods. The interest here is in population-level patterns, and thus the paleopathological indicators
will be those suitable for such analysis. That means a dependence on what might be called indicators of
multifactorial etiology, or nonspecific ones, with all their disadvantages and advantages. The main
advantage is ease of recording and sufficient prevalences within the relatively small numbers of
skeletons available per site for analysis. The indicators to be investigated are porotic hyperostosis
(usually indicative of anemia or other nutritional deficiencies during childhood), tibial periostitis
(usually indicative of an infectious condition), linear enamel hypoplasias (formed by growth arrest
episodes during childhood). These are certainly not the only paleopathological indicators that could be
investigated, but these at least are indicative of morbidity and thus indicate something of the quality
of life of past populations. These indicators, furthermore, will only be preserved in the skeleton if
the individual was generally able to survive the morbid episode. Thus, they are not the direct cause of
death, and their prevalence reflects that present in the living population. The important control must
be interobserver equivalence in the diagnosis and scoring of these indicators, a requirement met for
these skeletal samples.
However, for valid comparisons of prevalence in these skeletal samples, there should not be
differences in the age distribution of deaths. The vagaries of archaeological preservation and recovery
make it difficult to recover unbiased samples of all deaths in the past. Add to that the real problems
of accurate age estimation of adult skeletons. Thus, it is no surprise that there are significant
differences in the age distributions of skeletal samples. To be able to counter this situation and make
comparisons of prevalence, the technique of direct standardization, as employed in epidemiology, will be
applied. The resulting prevalences can then be compared to investigate how settlement size and density,
and any resulting time trend, influence morbidity and quality of life in Pre-Columbian Central Mexico.
The samples consist of two early agricultural villages, Tlatilco and San Buenaventura, and one early
monumental center with clear evidence of social stratification, Cuicuilco. Tlajinga 33 is from a
lower-status compound of artisans in the preindustrial city of Teotihuacan, the earliest large urban
center of Mesoamerica. Cholula, from the later large urban center of that name, is a sample from mostly
the laborers resident there. Tlatilco, San Buenaventura, and Cuicuilco contain individuals spanning all
the internal status differences present within their societies, while Tlajinga 33 and Cholula represent
mostly the lower status of their urban societies.
Results and Discussion. Overall, the situation reveals that the burden of morbidity increases through
time in Pre-Columbian Central Mexico, especially in some indicators such as tibial infection and LEH.
All of these changes are linked to a change from small settlements with less inequality and more varied
diet to larger, denser settlements with more inequality and more dependence on agricultural products.
The trend in porotic hyperostosis in the highlands is that Cuicuilco had the highest prevalence and then
in the later urban centers, it falls. For tibial infection, at best, it remains the moderate incidence
that has always been present here. It appears as if the prevalence decreases from Tlatilco to Tlajinga
but then increases dramatically in the latest site of Cholula. LEH also increases or remains at a high
incidence in all later sites, where only Cholula shows some decrease.
The agricultural villages and later centers of Mesoamerica always have what might be characterized as
moderate incidences of pathological indicators, indicating that morbidity was common in the daily lives
of these people. It is unfortunate that there are no foraging skeletal samples, from earlier than 3,000
years ago, available at this point to be better able to contextualize the time trend. The results here
indicate that changes in increasing dependence on agricultural products in the diet, larger and denser
settlements, and increasing social differentiation seem to lead to general higher burdens of morbidity.
In that, the past reflects the present situation in the Bain of Mexico. However, even the early
agricultural villages have incidences of some indicators as high as later urban centers. Were the arid
highlands of Mesoamerica always present a difficult place to make a living?