The prehistoric transition to agricultural dependence has been well-studied for a number of regions of the world; yet the effects on maternal health have been largely overlooked.
A massive population expansion associated with the advent of agriculture, referred to as the Neolithic demographic transition, has largely been considered a consequence of higher fertility rates associated with a decrease in the period between the birth of children. These processes would have imposed considerable biological demands on the bodies of Neolithic women.
In a research article recently accepted for publication in the American Journal of Human Biology, James Watson, an assistant curator of bioarchaeology at the Arizona State Museum at The University of Arizona and an assistant professor of anthropology, along with Misty Fields and Debra Martin from the department of anthropology and ethnic studies at the University of Nevada, Las Vegas, explore what this would have meant for oral health among women undergoing the Neolithic transition in the Sonoran Desert.
Archaeological research has shown that, in general, the shift to agriculture caused a global decline in human health related to two broad phenomena. The first was that the trend toward large sedentary communities engaged in agriculture led to poor sanitary conditions and the spread of communicable diseases. In addition, significant changes in diet from this change led to nutritional deficiencies, developmental problems and diminished immune response to disease.
Prehistoric agriculturalists also were seen to develop more oral disease when compared with foraging societies. Much of the dental decay experienced among agriculturalists has been associated with the consumption of softer, processed domesticated plants, which tend to stick to tooth surfaces and between teeth and gums.
Demands of reproductive biology have long been recognized to add an additional health burden to women's bodies, such as osteoporosis, and oral health is no exception. A 2006 report from the American Academy of Periodontology said that women are at increased risk for oral health problems over men the same age due to physiological changes associated with hormonal fluctuations that occur throughout their life span.
The vast majority of hormonal changes in women are associated with the female reproductive cycle. Clinical research indicates that pregnancy-related changes to the oral environment can affect dental health, so that without proper care, oral health can decline, leading to lifelong health problems specific to women.
The study by Watson and his colleagues focused on testing the relationship between women's dental health and agriculture in a sample of prehistoric skeletal remains from the archaeological site of La Playa in northwest Mexico.
The residents of La Playa were sedentary forager-farmers undergoing the Neolithic transition roughly between 1,600 and 200 years ago. Their diet included wild animals, wild plants such as cactus fruits and pads and mesquite tree beans, and domesticated maize, squash and beans, all of which can contribute to cavities.
Watson and the others found that both men and women suffered equally from cavities at La Playa, but women lost far more teeth than men as they aged, losing up to three times as many teeth by the final decades of life. Although more cavities in women could have contributed to this tooth loss, the researchers hypothesized that a stronger contributing factor was the loss of supporting bone structure from an overall reduction in bone mineral density, which is linked to factors that contribute to osteoporosis and possibly to periodontal disease.
In this case they surmised that physiological changes associated with hormonal fluctuations, accentuated by increased fertility rates associated with the Neolithic transition, modified the supporting bony structures of women's teeth at La Playa to produce greater tooth loss.
The revelation that female reproductive physiology negatively affects oral health is an essential consideration for examining oral disease epidemiology. The results of the study also demonstrate that there are more complex processes involved in the development of long-term health trends during the childbearing years in the life history of a woman.