Polygyny as social and biological differentiation among Toposa agro-pastoralists of Southern Sudan

A demographic survey of eight Toposa villages in Southern Sudan was undertaken to delineate patterns of infant and childhood mortality. Among these predominantly egalitarian agro-pastoralists few standard socio-economic variables useful in the detection of demographic differentials were found. Instead, polygyny was used as a measure of social differentiation, hypothesizing that social differentiation induces demographic differences between polygynous and monogamous marriages. Analysis indicated social differentiation through gerontocracy, while significant differences in mortality and fertility levels were found berween monogamous and polygynous marriages, with the latter featuring higher fertility and mortality levels. Underlying rationale for these differences were sought through consideration of social and biological factors.