Figure 4.

Estimated relationship between the intrinsic rate of natural increase, r, and age at menopause for four cases: (i) no effect of mother or grandmother on child survival; (ii) death of mother assumed to result in 13.4-fold increase in mortality of children aged 0–1 years and 11.7-fold increase in mortality of children aged 1–2 years and death of grandmother assumed to result in 2.0-fold increase in mortality of grandchildren aged 1–2 years; (iii) as (ii) where the 11.7-fold increase in mortality of children aged 1–2 years following the death of the mother is assumed to decrease linearly between ages 2 and 15 years; (iv) as in (ii) where the the 2.0-fold increase in mortality of grandchildren aged 1–2 years following the death of the grandmother is assumed to decrease linearly between ages 2 and 15 years.