Professor Purdie’s article on the influence of ethnicity on osteoporosis was fascinating.1 However we cannot support the argument that evolution has determined racial differences in bone mass and thus a low prevalence of osteoporosis in certain racial groups.

As the article points out, there are differences in bone mass and fracture incidence between white and black women in North America.2 The data on male fracture incidence are more contentious and the references cited relate to studies of black residents of mental institutions and hip fractures in a small population in Charlottesville, USA, with an incidence of fewer than 25 fractures per annum.3-5 However, Farmer reports no difference in fracture incidence in North America between black men, black women, or white men.2 In Africa, many women have multiple pregnancies, prolonged lactation periods, and low dietary calcium intakes. Despite these factors, …