In the following chapters, I assess effects of helpers, marital status, growth, child spacing, and reputations on reproductive success (RS) of Hadza men and women. The first task of this chapter is to introduce the dependent variables: fertility, child survival, and an approximate indicator of Hadza lifetime RS. Having established our measures of RS, I compare features of the RS of men and women, reviewing aspects of the data that imply differences in the ways Hadza men and women may maximize their fitness.

Fertility

The childbearing careers of the 227 interviewed women were set out as a file in which each record represents a year in the woman's life, beginning at age 10 and ending in the year in which she was last interviewed. The total record lists 695 births in 4524 woman–years. Each record includes the woman's estimated age, decimal year of birth, whether or not she had a birth during the year, whether any of her children died during the year, her accumulated number of births, and number of living children. Other variables were added as the data processing proceeded, such as her marital status in each year, the identity of her husband, whether he was present or absent (divorced), and so on. The file was designed for analysis by logistic regression, predicting birth or no birth under various conditions. The best fit of probability of a birth to mother's age was to age + age2 + age3 (Chapter 7). Because women are represented for different lengths of time, some of the analyses use multilevel regression. This method also allows derivation of individual differences in fertility, as reported in Chapter 7 and as follows. For a few analyses, I used another summary measure, the number of births during each quinquennium of the woman's adult life.

Child survival

The lives of the 695 children of the interviewed women were set out as a file in which each record was a year in the life of a child. There were 5650 child–years of data, and 242 children died. Each record included the child's ID, its mother's ID, its year of birth, age, whether it survived the year or died during that year, and whether its data were censored, as in the final year in which it was observed.