During the Paleolithic period, or Old Stone Age, nomadic and seminomadic people engaged in hunting and gathering. Generations of small aggregate groups wandered in search of food for 2 million years. Armelagos and Dewey (1978) reviewed how their size, density, and relationship to the environment probably affected their health. These groups may have avoided many contagious diseases because the scattered aggregates were small, nomadic, and separated from other aggregates. Under these conditions, disease would not spread between the groups. Evidently the disposal of human feces and waste was not a great problem; the nomadic people most likely abandoned the caves they used for shelter once waste accumulated.

Small settlements were characteristic of the Mesolithic period, or Middle Stone Age, and the Neolithic period, or New Stone Age. Wandering people became sedentary and formed small encampments and villages. The concentration of people in these small areas caused new problems. For example, people began to domesticate animals and live close to their herds, which probably transmitted diseases such as salmonella, anthrax, Q fever, and tuberculosis (TB) (Polgar, 1964). These stationary people also domesticated plants, which may have reduced the range of consumable nutrients and may have led to deficiency diseases. They had to secure water and remove wastes, which often resulted in the cross-contamination of the water supply and the spread of waterborne diseases such as dysentery, cholera, typhoid, and hepatitis A.

In preindustrial times, large urban centers formed to support the expanding population. Populations inhabited smaller areas; therefore preexisting problems expanded. For example, the urban population had to resource increased amounts of food and water and remove increased amounts of waste products. Some cultures developed elaborate water systems. For instance, the Aztec king Ahuitzotl had a stone pipeline built to transport spring water to the inhabitants of Mexico City (Duran, 1964). However, waste removal via the water supply led to diseases such as cholera. With the development of towns, rodent infestation increased and facilitated the spread of plague. People had more frequent close contact with each other; therefore the transmission of diseases spread by direct contact increased, and diseases such as mumps, measles, influenza, and smallpox became endemic (Polgar, 1964). A population must reach a certain size to maintain a disease in endemic proportions (Table 2-1); for example, approximately 1 million people are needed to sustain measles at an endemic level (Cockburn, 1967).

Industrialization caused urban areas to become denser and more heavily populated. Increased industrial wastes, air and water pollution, and harsh working conditions took a toll on health. During the eighteenth and nineteenth centuries, there was an increase in respiratory diseases such as TB, pneumonia, and bronchitis and in epidemics of infectious diseases such as diphtheria, smallpox, typhoid fever, typhus, measles, malaria, and yellow fever (Armelagos and Dewey, 1978). Furthermore, imperialism spread epidemics to susceptible populations throughout the world because settlers, traders, and soldiers moved from one location to another, introducing communicable diseases into native population groups.

Although infectious diseases no longer account for a majority of deaths in the Western world, they continue to cause many deaths in the non-Western world. They also remain prevalent among low-income populations and some racial and ethnic groups in the West. Western diseases such as cancer, venous disorders, heart disease, obesity, and diabetes rarely develop in people from nonindustrial communities. These diseases usually appear when cultures adopt Western customs (Burkitt, 1978). Western diseases also seem to emerge when cultures transition into urban environments. Epidemiological studies suggest that common disease factors are changes in diet (i.e., increases in refined sugar and fats and lack of fiber) and environmental and occupational hazards. An increase in population and population density also increases mental and behavioral disorders (Garn, 1963).

The disease patterns and environmental demands changed when wandering, hunting, and gathering aggregates grew into large populations and became sedentary. Humans had to adapt to an overpopulated, largely urban existence with marked consequences for health; the leading causes of death changed from infectious disease to chronic illnesses.

From the early remains of human habitation, we recognize that early nomadic humans became domesticated and tended to live in increasingly larger groups. Aggregates ranging from family to community inevitably shared episodes of life, health, sickness, and death. Whether based on superstition or sanitation, health practices evolved to ensure the survival of many aggregates. For example, primitive societies used elements of medicine (e.g., voodoo), isolation (e.g., banishment), and fumigation (e.g., smoke) to manage disease and thus protect the community for thousands of years (Hanlon and Pickett, 1990).

The decline of Rome, which occurred circa 500 AD, led to the Middle Ages. Monasteries promoted collective activity to protect public health, and the population adopted protective measures such as building wells and fountains, cleaning streets, and disposing of refuse. The commonly occurring communicable diseases were measles, smallpox, diphtheria, leprosy, and bubonic plague. Physicians had little to offer in the management of diseases such as leprosy. The church took over by enforcing the hygienic codes from Leviticus and establishing isolation and leper houses, or leprosaria (Rosen, 1958).

A pandemic is the existence of disease in a large proportion of the population. One such pandemic, the bubonic plague, ravaged much of the world in the fourteenth century. This plague, or Black Death, claimed close to half the world’s population at that time (Hanlon and Pickett, 1990). For centuries, medicine and science did not recognize that fleas, which were attracted to the large number of rodents that inhabited urban areas, were transmitters of plague. Modern public health practices such as isolation, disinfection, and ship quarantines emerged in response to the bubonic plague (Box 2-2).

During the Middle Ages, clergymen acted as physicians and treated kings and noblemen. Monks and nuns provided nursing care in small houses designated as structures similar to today’s small hospitals. Medieval writings contained information on hygiene and addressed such topics as housing, diet, personal cleanliness, and sleep (Rosen, 1958).

Although the cause of infectious disease remained undiscovered, two events important to public health occurred during the Renaissance. In 1546, Girolamo Fracastoro presented a theory that infection was a cause and epidemic was a consequence of the “seeds of disease.” Also, in 1676, Anton van Leeuwenhoek described microscopic organisms but did not associate them with disease (Rosen, 1958).

The Elizabethan Poor Law, enacted in England in 1601, held the church parishes responsible for providing relief for the poor. This law governed health care for the poor for more than two centuries and became a prototype for later U.S. laws.

Communicable diseases ravaged the population that lived among unsanitary conditions, and many lives were lost. For example, in the mid-1800s, typhus and typhoid fever claimed two times more lives each year than the Battle of Waterloo (Hanlon and Pickett, 1990).

Edwin Chadwick called attention to the consequences of unsanitary conditions that resulted in health disparities that shortened the life span of the laboring class in particular. Chadwick contended that death rates were high in large industrial cities such as Liverpool, where more than half of all children born of working-class parents died by age 5. Laborers lived an average of 16 years. In contrast, tradesmen lived 22 years, and the upper classes lived 36 years (Richardson, 1887). In 1842, Chadwick published his famous Report on an Inquiry Into the Sanitary Conditions of the Labouring Population of Great Britain. The report furthered the establishment of the General Board of Health for England in 1848. Legislation for social reform followed, which concerned child welfare; factory management; education; and care for the elderly, sick, and mentally ill. Clean water, sewers, fireplugs, and sidewalks emerged as a result.

In 1849, a pathologist named Rudolf Virchow argued for social action—bettering the lives of the people through improving economic, social, and environmental conditions—to attack the root social causes of disease. He proposed “a theory of epidemic disease as a manifestation of social and cultural maladjustment” (Rosen, 1958, p. 86). He further argued that the public was responsible for the health of the people; social and economic conditions heavily affected health and disease; efforts to promote health and fight disease must be social, economic, and medical; and the study of social and economic determinants of health and disease would yield knowledge to guide appropriate action.

In 1849, these principles were embodied in a public health law submitted to the Berlin Society of Physicians and Surgeons (Rosen, 1958). According to this document, public health has as its objectives (1) the healthy mental and physical development of the citizen, (2) the prevention of all dangers to health, and (3) the control of disease. Public health cares for society as a whole by considering the general physical and social conditions that may adversely affect health and protects each individual by considering those conditions that prevent the individual from caring for his or her health. These “conditions” may fit into one of the following major categories: conditions that give the individual the right to request assistance from the state (e.g., poverty and infirmity), and conditions that give the state the right and obligation to interfere with the personal liberty of the individual (e.g., transmissible diseases and mental illness).

In 1854, an English physician, anesthetist, and epidemiologist named John Snow demonstrated that cholera was transmissible through contaminated water. In a large population afflicted with cholera, he shut down the community’s water resource by removing the pump handle from a well and carefully documented changes as the number of cholera cases fell dramatically (Rosen, 1958).