Demography of the Hadza, an increasing and high density population of Savanna foragers.

This is a report on the demography of the Hadza, a population of East African hunter-gatherers. In it, we describe the results of a census, and our estimation of age structure, survivorship, mean age of women at childbearing, number of live children, total population size and density, and rate of change since 1967. We show that relevant measures fit closely the stable population model North 6 chosen by Dyson to represent Hadza demography in the 1960s. We compare aspects of Hadza demography with surrounding non-Hadza and with the !Kung. Among other things, we find that the Hadza have a higher population density, higher fertility, and a faster population growth rate than do the !Kung. These demographic differences are consistent with our expectations, which were based on differences in the costs and benefits of foraging in the two regions. We also show that Hadza demographic parameters display remarkable consistency over the past 20 years. Since neighboring populations have been encroaching on the area used by the Hadza, and Hadza foragers have been subject to interludes of externally imposed settlement, this consistency is surprising. We discuss some of the implications.

PIP: The research objective was to obtain demographic information of the Hadza, hunter-gatherers from the Eastern Rift Valley, southeast of Lake Eyasi in eastern Africa, in 1985. The aim was to gain insight into their reproductive strategies and how local ecology affects the population. Fertility is assumed to increase where it is more difficult to feed offspring. Comparisons are made to the ]Kung reproductive model. Demographic data were obtained in a 1985 census among 36 camps plus 2 villages in eastern-Hadza-occupied territory in the Eastern Rift Valley. Previous demographic surveys in 1966-67 and 1977 and the Tanzanian Census of 1978 for neighboring populations were important as independent checks on the accuracy of family compositions and age structure. Null hypotheses were tested: that the 1985 data fit the model chosen by Dyson in 1967, or that the data fit the model chosen by Howell for the ]Kung. Data were collected on 1) the age structure of the population, 2) survivorship of people counted in the 1967 census, 3) the mean age of childbearing for mothers of small babies in 1985 and previous censuses, 4) the number of live children/women by age, and 5) calculation of the total population in 1967. 719 eastern Hadza were recorded for 1985 and density was calculated as .30/km squared of .74/sq mile. Density varies locally and with the seasons. With villagers excluded, the density is .24/km squared or .61/sq mile. The methods for constructing the age structure involved fitting a 3-term polynomial regression of individuals of known age against the distribution of all individuals by age rank, and estimating ages of reach rank with a regression equation. The results were not different from the 1967 data; age structure does vary with location. Mortality was closer to Dyson's North 6 stable population model, but very close to Howell's estimates for the ]Kung. The mean age of childbearing was 30.9 years which is later than the ]Kung. The findings support Dyson's conclusions, and reflect higher density, higher fertility (6.15 vs. 4.7), and higher rates of growth than the ]Kung. Bush-living Hadza were even more different from the bush-living ]Kung. A number of explanations for the differences are explored.

Towards understanding low contraceptive prevalence in African societies.

PIP: This article discusses contraceptive prevalence rates (CPRs) in sub-Saharan Africa, identifies some factors associated with CPR, and draws examples from the Asian experience. The author discusses the association between patriarchy and the low status of women with low acceptance and discontinuation of contraception. In Africa, dominant cultural practices so occupy women's time that there is little opportunity to be exposed to new ideas or to seek information on modern ways of life. By the time women are exposed to new ideas, the completed family size would be large enough to prevent acceptance of a small family norm. Polygamous settings are not conducive to adoption of contraception, when women compete for the attention of their husband by bearing a substantial number of children. Davis (1967) proposed that changes in social structures that protected pronatalist behavior would need to be changed before population policies could be effective. Thandani (1978) reiterated this view. The author identifies economic factors as key to fertility decline and urges a chronological compilation of historical events and social surveys to disentangle trends in fertility and its determinants. The author proposes that fertility decline would be brought about by the increased costs of children and the decline in benefits of having many children. Policy could increase resource limitations. Parental control that assures the transfer of benefits between parents and children is already being eroded without direct planned effort. Trends revealed by the Demographic and Health Surveys indicate that Africa is a region of low contraceptive prevalence, with the exception of Botswana, Kenya, and Zimbabwe. Modern method use is very limited. However, 27-40% of women have an unmet need for family planning. Understanding the desired family size is a prerequisite for deliberate fertility control and fertility decline.^ieng

Refining the issues for realistic population-development policies in Africa.

"Varied population issues have sprung up as the population-development question has received more attention with time.... This paper takes up [critical population] issues and refines them in the perspective of African realities for long-term development. It is argued that the assumptions on which the Coale-Hoover model is based are untenable in the African circumstances.... The issues [considered in this paper] and having a common denominator, namely, reduction of current high fertility, are as follows: (a) old age structure and prospects for economic development; (b) the danger for Africa of rapid decline in fertility; (c) maternal and child health advantages; and, (d) environmental protection."

Critical issues in population-development interrelationships and policy in Sub-Saharan Africa.

PIP: The relationship between population growth and socioeconomic development in Africa is examined. Using the example of Tanzania, the author argues that population growth has had no causal effect on development, although development variables have affected demographic variables. However, it is noted that rapid population growth limits the efforts of government to provide services and is associated with environmental degradation, and that there is a need to control population growth by lowering fertility.^ieng

Socialisation gap and high fertility behaviour among younger generations: evidence from Wasukuma of Mwanza Region, Tanzania.

PIP: A survey of the pregnancy histories of a random sample of 3000 rural and urban women of Sukuma ethnic origin in Mwanza Region, Tanzania, suggests that younger generations will have a completed fertility higher than older generations. A critical element in recent change has not been mere social aberration, but a new system of values that has been caused by modernization synonymous with westernization, with the school as the main vehicle of diffusion. Younger generations who have assimilated the new values are achieving higher fertility than their older counterparts, rather than the converse commensurate to modern behavior as has occurred in developed countries. After controlling for age at marriage and rural-urban location, for both groups of women, age at 1st pregnancy is lower the younger the woman is. In addition, birth intervals are shorter at younger ages. This higher fertility among younger generations is likely to be a result of changes in the institution of socialization about matters of child bearing and rearing. Those who have attended school have received a different kind of socialization and orientation to modern ways of living; consequently, they have no adult role model to follow upon leaving school. There are 2 factors encouraging early age at marriage or 1st pregnancy: 1) the monetization of the economy and the opportunity for younger men to establish their own households because of employment options away from the family farm, and 2) the decline in age at menarche has made girls look mature and attractive for marriage at an earlier age. The abandonment of traditional practices of child spacing has proved detrimental to the health of both mother and child. A solution that would both bridge the socialization gap and have an almost immediate and long-term effect would be the introduction of family life education.^ieng