In this chapter, the author aims to reports on new research among the Mukogodo that both confirms and elaborates upon the earlier findings. Between 1985 and 1987 he conducted fieldwork among the Mukogodo and collected data relevant to the prediction. The first hint that there might be female-biased parental investment came from their childhood sex ratio, which in 1986 was equivalent to 67 boys for every 100 girls. The limited measures of parental behavior and the lack of details about the effects of biased parental investment on the children themselves raised new questions. To assess patterns of parental investment, the author collected several different types of data, including systematic observations of the behaviors of caregivers and children, mothers' reports on their children's morbidity, and usage statistics for two local clinics. To assess children's growth performance, the author collected basic anthropometric data, including recumbent length, weight, and head circumference.