Hunting, gathering, and farming today
It is much easier to consider the health of contemporary people who hunt and forage or work in agriculture because the data are more accessible and detailed, and ecological factors specific to living hunter-gatherers and agriculturalists can be used effectively to understand the diet they eat and challenges to health they experience.
Data from living people can be surprising and can challenge our assumptions about the past.Hunter-gatherers
For example, although the general consensus is that fertility rates are low for hunter-gatherers both past and present, Pennington notes that hunter-gatherer total fertility rates are very variable and some of that is because ‘virtually all hunter-gatherers... are involved economically in one way or another with nonforaging people'.[153] Sexually transmitted diseases are also believed to affect fertility rates. Average age at death is low, as is life expectancy at birth; in a survey of the few studies of hunter-gatherer survival, Pennington notes a maximum in the Ache in Paraguay of thirty-seven years of life for newborns, but twenty-four years for the Agta in the Philippines. With respect to diet and health, which may also be termed ‘nutritional ecology' (interaction of diet, physical activity, and pathogenic agents, and their relationship to body composition, development, and function in a particular sociopolitical and natural environment), Cohen noted that people who are classed as hunter-gatherers have lean bodies and occasionally are hungry if resources are not plentiful (e.g. in particular seasons), but they have the ability to move on to find new resources.[154] Although there are great variations between hunter-gatherer groups on the proportions of plant and animal foods that make up their diet, affected by seasonal differences, hunter-gatherers generally have a low calorie and fat (especially saturated) intake and more fibre ingestion, along with higher micronutrient consumption (aided by greater physical activity).[155] Diet is generally well balanced, more varied, and higher in protein than a ‘farming diet', and in a study in the Kalahari, Truswell and Hanson found no evidence of a poor diet.[156] However, times are changing for living hunter-gatherers who are becoming acculturated and exposed to Western diets, while their natural resources become more challenging to access.
Common health problems of hunter-gatherers are parasitic infection, such as of the blood (malaria) and intestines (e.g. hookworm), and zoonoses (diseases spread from animals to humans), with infectious disease being the most common cause of death. Dental wear and abrasion, periodontal disease, and dental plaque are common, but caries is low. These low-density populations do not favour transmission of density-dependent diseases such as measles, tuberculosis, and influenza. The absence of permanent settlement also prevents the accumulation of waste, and consequent vermin, contamination of water supplies, and associated disease such as cholera. The degenerative diseases, especially associated with old age and Western living, are, overall, rare, but accidents are fairly common and associated with hunting, and hunting can also lead to exposure to zoonoses. Lactose tolerance is generally rare in hunter-gatherers, again illustrating how tolerance has evolved with the transition to agriculture. Hunter-gatherers are overall ‘moderately active' but with variation according to the seasons (as for farmers), but not as great as for people practising horticulture or agriculture.[157] It is difficult to know whether hunter-gatherers lived in an ideal world. Considering the contradictory evidence from many studies in bioarchaeology that hunter-gatherers were more healthy than agriculturalists, it is no easy task to make comparisons between past and present (‘more or less acculturated') hunter-gatherers, especially with rapid changes to the hunter-gatherer way of life today reflected in changes to the ecosystem and a decline in wild animals to hunt.
Farmers
Exploring health in agriculturally based populations today as a comparator for the past is similarly fraught with problems because the ways in which agriculture is practised globally vary considerably, from developed to developing countries. The food grown and the domesticated animals kept are diverse, such that each ecological niche, in its broadest sense, will contain multiple facets that in turn affect the quality of the diet and a population's health.
Chamberlain notes that agricultural populations have high growth, but that this is not consistent, and growth is very much related to the carrying capacity of the area.[158] Farmers also have higher fertility, as noted above, which is due overall to having a more settled community and secure food resources. Today some traditional agricultural communities still have practices that limit family size, such as infanticide and abortion, but other practices can lead to high birth rates and, the more people there are, the greater capacity there is for agricultural work to be carried out.[159] For example, if women have children that are born very close to each other chronologically, this does not matter as much as for a hunter-gatherer mother who would have to carry and care for her children between temporary camps and while gathering food. Weaning foods are also readily available in agriculture contexts. Among the many studies of health in agricultural populations today, a range of subject areas is approached but particularly includes occupational risks. For example, respiratory health of farmers has been reported, revealing increased asthma associated with dust inhalation and there are dangers for people practising agriculture in areas where soil may be contaminated and helminth infections associated with contaminated water and crops.