Grandfather hypothesis rejected?

In biological anthropology there is a Grandmother Hypothesis as an explanation for why adult human females live so long after their reproduction ceases, and, why menopause occurs in the first place (male fertility tapers off over time, while women undergo a concerted physiological change which shuts down their ability to reproduce). The basic idea is that beyond a particular age women can increase their own genetic fitness to a greater extent by investing in their daughters reproductive output. The idea is pretty easy to illustrate. Imagine an allele, M, which induces menopause in an autosomal dominant manner (only one copy is necessary). If there is a woman who exhibits a de novo mutation for this trait, and her biosocial phenotype results in increased fitness then that allele will have a higher fitness than the "wild type." In the next generation half her daughters will exhibit the same trait and be ...