Grandmother hypothesis [New Scientist]
see also: Hill, K. and Magdalena Hurtado, A. 1991 The Evolution of Premature Reproductive Senescence and Menopause in Human Females: An Evaluation of the "Grandmother Hypothesis" Human Nature 2: 313-350.
Biographical article on Desmond Morris [Mail & Guardian]
mentioning his theory of hemispherical breast and buttock shape
(and a whole lot of other interesting things about the man).