@unpublished{KWWwalls,
    TITLE = {The Age-Specific Force of Natural Selection and Walls of Death},
   AUTHOR = {Kenneth W. Wachter and Steven N. Evans and David R. Steinsaltz},
       ID = {info:oai/arXiv.org:0807.0483},
     YEAR = {2008},
 ABSTRACT = {W.D. Hamilton's celebrated formula for the age-specific force of
             natural selection furnishes predictions for senescent mortality due
             to mutation accumulation, at the price of reliance on a linear
             approximation. Applying to Hamilton's setting the full non-linear
             demographic model for mutation accumulation of Evans et al. (2007),
             we find surprising differences. Non-linear interactions cause the
             collapse of Hamilton-style predictions in the most commonly studied
             case, refine predictions in other cases, and allow Walls of Death
             at ages before the end of reproduction. Haldane's Principle for
             genetic load has an exact but unfamiliar generalization.},
   }