Human Hips, Breasts and Buttocks: Is Fat Deceptive?

‘hen males invest parentally, as in humans, males as well as W females are likely to exercise some choice (Darwin 187 1; Trivers 1972). The traits males use are expected to be those which reflect the female’s reproductive value (future lifetime expected reproduction; Fisher 1958; Williams 1966a,b) and current reproductive status (e.g., fertile, pregnant; cf. Gallup 1982, 1986). We will term this combined criterion “reproductive probability.” Previously, we have argued (Alexander 1971; Low 1979a) that breasts, hips, and buttocks as sexual signals evolved in the context of females competing for the attention and parental commitment of powerful, resourcecontrolling males. We hypothesized that (1) large breasts indicate to males the ability of a female to supply a large amount of high-quality milk uninterruptedly for a period of years and (2) broad hips reflect ability to carry a fetus and give birth with relative ease. We also suggested that when enlargement of hips and breasts result mainly from fat deposits the signal is deceptive (cf Barnett 1983, and Smith 1984). There is little disagreement that fat provides efficient energy storage (e.g., Stini 1981), and the observation that human females tend to have greater fat storage than males has been suggested to result from the high-