Open Peer Commentary
Coall & Hertwig (C&H) suggest that, because grandparental investments do not impact on child mortality in low-risk societies, fitness effects are not plausible any more. We found that grandparental investments could very well alleviate contemporary constraints on fertility. Cultural factors may influence both the occurrence and impact of grandparental investments.
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