Abstracts (first author)
Sex differences in natural selection on reproductive scheduling and longevity in humans
Author(s): Lummaa V
Despite senescence with age, most animals retain ability to reproduce until relatively close to death. Humans provide an interesting case because with mid-life menopause, women show a radical de-coupling of senescence in reproductive and somatic systems, leading to up to half of total lifespan spent post-reproductive. By contrast, men maintain reproductive ability until much later ages. Although men thus sire offspring at older ages than women, nearly all contemporary human populations exhibit sexual dimorphism in lifespan with women outliving men by on average of five years. While proximate causes for such fertility and lifespan differences between the sexes are well-known, our understanding of the underlying evolutionary forces is much more limited. I use pedigree data on pre-industrial Finnish men and women collected by local clergymen: (1) to address different evolutionary hypothesis for the benefits of menopause and post-reproductive longevity in women; (2) to assess whether selection on overall lifespan differs between the sexes; (3) and to estimate sex-specific heritabilities for, and genetic correlations between, lifespan and fitness to predict evolutionary trajectories for lifespan and sexual dimorphism. Understanding sex differences in rates of senescence in reproduction and survival, both key life-history traits, provides insights into how differing selection pressures can mould rates of senescence and ultimate longevity within a species. I hope to illustrate that although evolutionary studies on contemporary human populations suffer from many limitations, some of the data available on humans offer interesting research opportunities also for evolutionary biologists with potential implications for studies on demography, public health or anthropology.