Sex differences in bone loss--an evolutionary perspective on a clinical problem.

The dramatic increase in the world's population that has occurred over the past 100 years has come largely through reductions in death due to infectious disease. An epidemiologic transition to a preponderance of deaths due to degenerative conditions such as cardiovascular disease and cancer is occurring in the developing countries as well as in the industrialized ones. In the industrialized countries, demographic profiles now reflect the increased life expectancies of both sexes. However, female life expectancies exceed male by six or more years. Further change in mortality patterns will accompany success in the reduction of the number of mortalities attributable to such degenerative conditions as cardiovascular disease and cancer. In the 21st century, conditions associated with sensescence will be of increasing concern. Adaptive strategies that enhanced reproductive success throughout most of human evolution may now prove detrimental to human health as average life expectancies reach unprecedented length. In this environment, differences in the survival mechanisms deployed by males as opposed to females will become increasingly important.