Linus Pauling's first contribution to :he aging literature came, unwittingly, in 1931. In that year he predicted, on theoretical grounds, the existence of the superoxide radical.' His first deliberate foray into the field of aging was his 1958 paper on " The Relation Between Longevity And Obesity in Human Beings", read before the National Academy of Sciences. Pauling appears then to have been more interested in curve-fitting than in obesity per se; the thrust of the paper is that a quadratic function, with its minimum at normal weight, fit the observed relation between weight and life-shortening better than did the commonly-used linear term. Deviation to either side of the optimum (normal) weight is associated with decreased longevity, as Pauling's curve predicts. Pauling's approach here is consistent with his later insistence on optimum concentrations of biomolecules in orthomolecular medicine.