Sir Philip Sidney Game - Criticisms

Criticisms

The empirical study of chick begging has cast some doubt on the appropriateness of the Sir Philip Sidney game and on the handicap principle as an explanation for chick begging behavior. Several empirical studies have attempted to measure the cost of begging, in effect measuring c. These studies have found that although there is a cost, it is far lower than would be sufficient to sustain honesty. Since the actual benefits of food are hard to calculate, the required value of c cannot be determined exactly, but it nonetheless has raised concern.

In addition to the empirical concern, there has been theoretical concern. In a series of papers, Carl Bergstrom and Michael Lachmann suggest that in many biologically possible cases we should not expect to find signaling despite the fact that it is an evolutionarily stable strategy. They point out that whenever a signaling strategy is evolutionarily stable, non-signaling equilibria are as well. As a result, evolutionary stability alone does not require the evolution of signaling. In addition, they note that in many of these cases the signaling equilibrium is pareto inferior to the non-signaling one – both the chick and parent are worse off than if there was no signaling. Since one would expect non-signalling to be the ancestral state, it is unclear how evolution would move a population from a superior equilibrium to an inferior one.

Both of these concerns led Bergstrom and Lachmann to suggest a modified game where honesty is maintained, not by signal cost, but instead by the common interest inherent in interaction among relatives. In their partial pooling model, individuals have no incentive to lie, because the lie would harm their relative proportionally more than it would help them. As a result, they do better by remaining honest.