Open Peer Commentary
As societies industrialize, the age profile of consumption tilts strongly toward the elderly, while elder labor supply drops. Low fertility and long life lead to population aging. For millennia, material resources have, on net, flowed downward from older to younger within populations, but now in many rich societies net flows have reversed and go upwards from young to old.
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. email@example.com http://www.uwa.edu.au/people/david.coall; Department of Psychology, University of Basel, 4055 Basel, Switzerland. firstname.lastname@example.org http://www.psycho.unibas.ch/hertwig