[The remarkable rise in life expectancy and how it will affect medicine]

Life expectancy has increased at a steady pace in industrialized countries over the last 160 years. A slowdown is not evident: Since 1950 the number of people celebrating their 100th birthdays has at least doubled each decade. This increase in survival is the result of economic developments, social improvements and advances in medicine. Although the belief that old-age mortality is intractable remains widespread, life expectancy is not approaching a limit. Rather, the evidence suggests that ageing is plastic and that survival can be extended by various genetic changes and non-genetic interactions. Increases in life expectancy are largely attributed to improvements in old-age survival. It is a reasonable scenario that life expectancy will rise further in coming decades, supported by advances in the prevention, diagnosis and treatment of age-related diseases. If the trend continues, life expectancy in Germany will rise to over 90 years in the first half of this century. Many official forecasts, however, have assumed lower figures which can have severe consequences both for public and private decision making.

Mitochondrial DNA and microsatellite variation in the eider duck (Somateria mollissima) indicate stepwise postglacial colonization of Europe and limited current long-distance dispersal

To unravel the postglacial colonization history and the current intercolony dispersal in the common eider, Somateria mollissima, we analysed genetic variation at a part of the mitochondrial control region and five unlinked autosomal microsatellite loci in 175 eiders from 11 breeding colonies, covering the entire European distribution range of this species. As a result of extreme female philopatry, mitochondrial DNA differentiation is substantial both among local colonies and among distant geographical regions. Our study further corroborates the previous hypothesis of a single Pleistocene refugium for European eiders. A nested clade analysis on mitochondrial haplotypes suggests that (i) the Baltic Sea eider population is genetically closest to a presumably ancestral population and that (ii) the postglacial recolonization progressed in a stepwise fashion via the North Sea region and the Faroe Islands to Iceland. Current long-distance dispersal is limited. Differentiation among colonies is much less pronounced at microsatellite loci. The geographical pattern of this nuclear genetic variation is to a large extent explained by isolation by distance. As female dispersal is very limited, the geographical pattern of nuclear variation is probably explained by male-mediated gene flow among breeding colonies. Our study provides genetic evidence for the assumed prominent postglacial colonization route shaping the present terrestrial fauna of the North Atlantic islands Iceland and the Faroes. It suggests that this colonization had been a stepwise process originating in continental Europe. It is the first molecular study on eider duck populations covering their entire European distribution range.