Challenges to health at the transition to agriculture
Through time, up to the present, and as the population of the world has increased, the production of food through farming plants and animals has continued to grow and expand, with increasing intensification of food sources evident.[130] The use of chemical fertilizers and pesticides, improved irrigation systems for crop production, and clearance of land, with all their subsequent impacts on the environment, are well known, as is the effect of intensification of livestock production, which leads to deforestation, factory farming, special feeds, drugs to prevent and treat disease, pollution of land and water from manure, selective breeding, and consequent concerns over animal welfare.
Indeed, the World Health Organization has recently reviewed the connections between environmental change, modern agricultural practices, and the occurrence of infectious diseases, finding that there are now ‘increased opportunities for contact between humans and the animal hosts and reservoirs of pathogens'.[131] Genetic manipulation of crops and animals to produce higher yields is also a concern, and yet advantages of doing so are frequently publicized (e.g. inserting genes into crops to produce a ‘natural pesticide', changing the timing for when fruit ripens, and increasing a crop's ability to live in environmental extremes).[132] In recent years there have been escalating campaigns to counteract concerns about how the agricultural industry functions. However, whether the initial move to farming was the result of an increasing population, or instead farming enabled a larger population to be supported, remains a constant debate, as does how detrimental to diet and health farming was and is. Clearly, access to an adequate and good quality food supply was, and continues to be, necessary for everyone to grow normally, and to be healthy and happy. When this is not possible, this is today termed ‘food insecurity', and may be caused by a number of factors such as climate change, overpopulation, soil degradation, and conflict.One of the key questions that has been asked in the past, and continue to be asked, is what happens to demography, diet, and health in populations with the transition to agriculture from hunting and foraging.[133] This first of three transitions is studied alongside two later ones: the second transition, industrialization, which saw a decline in mortality with improved living conditions alongside the development of antibiotics, and a rise in chronic non-infectious diseases such as cardiovascular problems (heart disease and ‘strokes') and cancer; and, more recently, the third transition, the reemergence of infectious diseases and new infections along with resistance to antibiotics. The developing world is of course experiencing the second and third transitions later than developed countries.[134] However, it is well known that socioeconomic, political, and environmental factors all have their part to play in health at these transitions, and ultimately affect the diet people ate and are eating, and their physical and mental health.
Archaeological human remains capture a snapshot of how people's health was affected by changes in their diet and general way of life with the transition to agriculture when compared to their hunter-gatherer ancestors. It is essential to bear in mind that skeletal evidence for health and welfare in human remains from archaeological sites is the closest we can get to interpreting and understanding this aspect of the past. Being unhealthy and eating an unbalanced diet potentially affects the very function of any society past or present, so bioarchaeology provides key data for answering broader questions about society in a world of agriculture.
Essentially, most studies in bioarchaeology have found that health declines through time, and especially at economic transitions and as society becomes more complex.[135] Indeed, medical anthropological studies (the ‘application of anthropological theories and methods to questions of illness, medicine, and healing') have provided bioarchaeology with a wealth of data on the effect of farming on demography and health and have compared health in pre- agricultural and agricultural communities.[136] [137] [138] [139] For example, new diseases appear and fertility and population numbers and density increase with agriculture.
As McElroy and Townsend suggest, agricultural communities today do practise controls over population numbers, for example through prolonging breastfeeding, but the young are also ‘put to work' early in their lives. Medical anthropology, however, has also shown us that many health problems facing the Western world are not seen in people who have not adopted a ‘modern' way of life and do not eat an agriculturally based diet.11 Evolutionary medicine, which uses an evolutionary perspective to understand why the body is not better designed and why diseases exist, has alerted us to the effects of agriculture on health and emphasizes the benefits and costs of agriculture to the world's population today.12 Evolutionary medicine, furthermore, ‘hypothesizes a mismatch between human biological evolution and health conditions in industrialized societies', but it is notable that few of the ideas promoted have been fully explored in any scientific way.13 Clearly, bioarchaeology is in a position to exploit both medical anthropology and evolutionary medicine to understand the past, but it also informs the two disciplines by providing the deep-time perspective in helping us understand the here and now.This chapter focuses on what kind of evidence can be productively used from human remains to tell us something about a population's diet and health, and to address the questions of how agriculture contributes to our health and diet and how bioarchaeology can help us understand this relationship better. It first describes the nature of bioarchaeology and how and what type of data can be collected, and then the chapter unfolds to consider:
• What kind of diet and health problems face hunter-gatherer and agricultural communities today, and our ancestors at the agriculture transition, and why.
• How they are recognized in human remains and some problems of interpretation.
• Particular health problems and dietary-related conditions that characterize ‘diet' and ‘living environment'.
The dialogues, necessarily, reach into the archive of biomolecular analyses and primarily, stable isotope analysis as an indicator of diet. The chapter concludes by looking forward to the future.