1. Pre-Transitional Populations I: Historical and Anthropological Demography
Demographic growth has not been uniform over time. Periods of expansion have alternated with others of stagnation and even decline; and the interpretation of these, even for relatively recent historical periods, is not an easy task. The numerical progress of population has been, if not dictated, at least constrained by many forces and obstacles which have determined the general direction of the path of its growth. These can be categorised as biological and environmental. The former are linked to the laws of mortality and reproduction which determine the rate of demographic growth; the latter determine the resistance which these laws encounter and further regulate the rate of growth. Biological and environmental factors affect each other reciprocally and so are not independent of one another. For the most part the mechanisms for re-establishing an equilibrium of population growth are the product of choice (fertility, nuptiality and migration) although some are automatic. The sizes of households and families have varied over time, but they seem to have been similar in different societies despite differences in the types of households. It has to be noted that the European marriage and family formation is neither universal nor is it totally unique.
In the long record of human life on earth – a record that by some archaeological accounts may go back as much as 2 million years – the population problem has generally not been one of overpopulation. When looking at pre-transitional societies and population growth one has to consider some figures first: the 1 million inhabitants of the Palaeolithic Age, the 10 million of the Neolithic, the 100 million of the Bronze and the 1 billion of the Industrial Revolution. These few figures clearly show us that demographic growth has not been uniform over time. As mentioned above, the numerical progress of a population has been, if not dictated, at least constrained by many forces and obstacles which have determined the general direction of the path of its growth. These can be categorised as biological and environmental and they affect each other reciprocally and so are not independent of one another. The following principal factors are thought to have regulated group size in pre-transitional societies:
- Mortality (especially high rates of infant mortality)
- Life expectancy at birth
- Environmental constraints (including catastrophic events)
For the most of human history fertility and mortality must have remained in virtual equilibrium as the rate of population growth was very low. Estimates of growth rate are about 0.06% from 0 A.D. to 1750. It has been estimated further that fertility was just 1.5% greater than mortality. Although their growth rates must have been similar, the relationships between the total fertility rate and the life expectancy at birth for Palaeolithic and Neolithic populations are assumed to have been very different. According to a well-accepted opinion, the Palaeolithic, a hunting and gathering population, was characterised by lower mortality, due to its low density, a factor that prevented infectious diseases from taking hold and spreading, and moderate fertility, compatible with its nomadic behaviour. For the Neolithic, a sedentary and agricultural population, both mortality and fertility were higher as a result of higher density and lower mobility. It is believed that in the primarily rural societies of past centuries, which lacked modern birth control and effective medical knowledge, both the number of births per woman and the life expectancy at birth might vary considerably. The number of children per woman ranged from less than 5 to more than 8 and life expectancy ranged from 20 to 40 years. (Daugherty and Kammeyer; Livi-Bacci)
The mechanisms of growth must continually adjust to environmental conditions (can be called environmental friction), conditions with which they interact but which also present obstacles to growth, as attested by the millennia during which the population growth rate has been very low. In a justly famous essay, Carlo Cipolla wrote: “It is safe to say that until the Industrial Revolution man continued to rely mainly on plants and animals for energy. It is this subordination to the natural environment and the resources it provides that constituted a check to population increase, a situation particularly evident for a hunting and gathering society. A model has been devised that effectively describes a double check on population increase in hunter gatherer societies. The first check is imposed by natural limits of vegetal and animal production which define the maximum number of individuals that can be fed. The second check relates to the incompatibility of very low population density with the survival of a stable population group. In order to ensure a reasonable choice of partners and to survive catastrophic events these groups must not be too small. The methods for re-establishing equilibrium are in part automatic (e.g. slowing down of body growth in response to food shortage), but for the most part they are the product of choice (fertility, nuptiality, migration). Different examples will be considered showing how pre-transitional societies have made conscious efforts to control the size of their households and families. (Livi-Bacci)
Between 1963 and 1973 a group of scholars led by R.B. Lee studied the !Kung San, a nomadic population that lived by hunting and gathering in the Dobe Area of northern Botswana and was at that time beginning a gradual process of settlement. In order to study the process by which the population has been formed over a lifetime of living people, and in order to gain as much information as possible about this small population, all the adult women living in the Dobe area were interviewed in detail about their marital and reproductive histories. The ages of the people were estimated as well. About half of the 165 informants married before their first menarche and about half later. The curve of first marriages starts as low as 9 but involves few women until about 15 and is essentially complete by 20. The maximum number who will never marry is essentially the same number married by 20, but the phenomenon of failure to marry is extremely rare among these people. It has to be noted that the first marriages often have little demographic or lasting social significance to the !Kung. If the young woman does not care for her husband she may simply leave him and go home to her family. Women’s wishes are generally respected concerning marriage, and women commonly form and dissolve several short marriages brief marriages in the early, teenage years. Both divorce and remarriage are simple and hold little handicaps for a woman at any age. Therefore while most of the women are married at any point of time during their reproductive years, the divorce rate throughout life is substantial.
The age of puberty among the !Kung women is late, between 15 and 17, and a long period of postpuberty sterility follows. The first life birth tends to be at the age of 19.5 and the chances of death during first year are about 20%. If the baby dies the mother may conceive again in as little as a few months and probably within a year. The timing of the next birth depends to some extent on age; younger women have their babies somewhat closer together than older women. The birth intervals are three to five years and thus they are very long for a population not practicing modern birth control. They are a result of the continuation of breastfeeding until as late as the third or the forth year. Consequently, the average number of children per woman is fairly low (4.7). The maximum number of live births is only 7 and the variance of the number of live births is small.