Open Peer Commentary
This commentary suggests that there is more continuity in pre- and post-demographic transition populations with respect to grandparental investments than is assumed by Coall & Hertwig (C&H). Recent research employing high-quality data supports the claim that sex-biased grandparental investments are likely to exist in industrialized societies, and that the economic status of grandparents is related to their long-term fitness.
Grandparental investment: Past, present, and future David A. Coall and Ralph Hertwig School of Psychiatry and Clinical Neurosciences, University of Western Australia, Fremantle, Western Australia 6160, Australia. firstname.lastname@example.org http://www.uwa.edu.au/people/david.coall; Department of Psychology, University of Basel, 4055 Basel, Switzerland. email@example.com http://www.psycho.unibas.ch/hertwig