Signalling among relatives. Signalling among relatives.
Talk is cheap.
The Sir Philip Sidney game has been used by numerous authors to show how signal cost can facilitate honest signalling among relatives. Here, we demonstrate that in this game, honest cost-free signals are possible as well, under very general conditions. Moreover, these cost-free signals are better for all participants than the previously explored alternatives. Our results show that cost-free or inexpensive signals, as observed empirically, fall within the framework of signalling theory.