The effects of grandparent survival on child survival and mean interbirth interval, both independent of and relative to parent survival, were investigated in a historical population. Families for the data set were reconstituted from the parish and census records of Cambridgeshire, 1770–1861. In a logistic regression analysis, only the mother’s and the maternal grandmother’s survival were found to be significant predictors of child survival. Maternal grandmother’s survival was found to influence child survival both via maternal survival and independent of maternal (...) survival. Grandparent survival was not found to influence mean interbirth interval. These findings are reviewed with respect to other studies of grandmothering, the Grandmother Hypothesis, and the evolutionary significance of human female postreproductive lifespan. (shrink)

Epigenetics impacts gene–culture coevolution by amplifying phenotypic variation, including clustering, and bridging the difference in timescales between genetic and cultural evolution. The dual inheritance model described by Uchiyama et al. could be modified to provide greater explanatory power by incorporating epigenetic effects.