Comment: fertility, mobility, and changing household dynamics in South Africa.

Much has changed since the transition to democracy in South Africa more than a decade ago. Racial barriers are breaking down, a small but emerging black middle class has sprung up, and South Africa has become a major migration destination for people from all over Africa. But equally true, as evidenced by the papers in this section, is the persisting legacy of the apartheid era. Patterns of disease, population movement, household structure, and fertility continue to be shaped by severe inequalities in the distribution of wealth and resources. While such factors were well-known features of apartheid-era South Africa, it is perhaps less well known that postapartheid South Africa remains one of the world’s most unequal societies. The country’s severe HIV epidemic is superimposed on this reality. The three papers in this section address the epidemic – and how it impacts on and is impacted by fertility, migration, and household coping strategies. Rural areas in South Africa continue to demonstrate remarkable fluidity, and many places like Agincourt have experienced rapid change in the last decade. Household fluidity, fuelled by migration and HIV mortality, has become even more pronounced with increasing numbers of women entering the migrant labour market. These rapidly changing conditions underscore the central strength in the data brought together in this issue: a health and demographic surveillance system that has been in place since 1992 and has generated quality data on approximately 70,000 people in a rural, former ‘‘homeland’’ area in the northeast of South Africa. All of the papers in this section offer longitudinal analyses of these data, shedding light on the changing dynamics of fertility and rural livelihoods during this critical period of South Africa’s political and social transition. Garenne and colleagues show the consistent decline in fertility over the last 25 years, when the fertility rate decreased from 6.0 in 1979 to 2.3 in 2004, and the net reproduction rate declined to 1. This decline is faster than expected and represents perhaps the first time that fertility below replacement level has been measured in rural Africa. Garenne estimates that HIV is responsible for about 20% of the fall [1]. Concurrent with the measured decline in fertility, Madhavan & Schatz examined household structure and composition in 1992, 1997, and 2003. Their findings – that average household size decreased, that the proportion of female-headed households increased, and that the proportion of households with at least one maternal orphan doubled – point again to the impact of the HIV epidemic [2]. High mortality due to AIDS is already restructuring family coping strategies, decisions on whether or not to migrate and countless other variables that have yet to be examined. Collinson’s paper addresses the complexity of defining ‘‘urbanization’’ in a dynamic environment characterized (at least in part) by the maintenance of family ties to rural areas and the associated largescale circular migration so prevalent throughout southern Africa [3]. He rightly makes the point that, if we define urbanization as simply a massive, permanent movement to town, we end up missing much about the complexity, frequency, and indeed impact of such movement. His comparison between