Biologists have known about maternal effects for a long time: the status of the mother can influence the future development of her embyro. To use a plant example, plants will disproportionately provision seeds with different amounts of stored nutrients. This can affect how seedlings grow–and, consequently, affect the future growth of the adult plant.
Researchers in Sweden have found that in a remote Swedish town, Overkalix, that there is a link between grandparents' food supply and grandchildrens' mortality. What's interesting is that there are effects in both sexes, which appear to be mediated by the X and Y chromosomes (it's not clear to me how males would influence offspring development). Even more curious is the observation that the food shortages must occur at precise points in life to influence the grandkids.
I'll be interested to see what the mechanisms for this are. Any thoughts? (Lil' Baby Jebus is not an answer...)
Update: maybe some kind of bizarro, long-term (really long-term) DNA methylation is happening? Or maybe some kind of RNAi type of thing? Hell if I know...