Studies of changes in longevity address two main questions. Firstly, why does life expectancy vary in different parts of the western world? Secondly, what are the prospects of human longevity: a life span of no more than 85-90 years on average, or the possibility of reaching much higher ages? The study of longevity and its relation to changes in social circumstances, health care and the number of available general practitioners might be of importance for health care planning. Sweden has a special responsibility to use its unique system of health statistics for such studies. The increase in longevity has inspired many scientists to try to commercialize the results of their studies in various models, and to sell products that are supposed to prolong life. "Science of longevity medicine" is a concept from which serious researchers want to distance themselves.