Wherever there are organisms, there are signals. Whether you are walking through a forest, sitting in a meadow, or swimming along a coral reef, your senses are bombarded with messages, most of the produced by non-human signallers and intended for non-human receivers. Calls, patterns, colors, fragrances - these are just a few of the modalities by which signals are sent and received.
To a certain degree these signals must be honest, at least on average. After all, if they were not honest, the intended signal receivers would evolve to ignore them. And if signal receivers ignored these messages, they would be useless - and signallers would eventually evolve not to send them. But why do these signals stay honest? In the short run, at least, there would sometimes seem to be advantages to deception.
Much of honest signalling theory can be thought of as an attempt to answer this question. Though the problem is simple to express, the solution is by no means obvious:
Two individuals have access to different information.
They could both gain if they could honestly share this information.
However, their interests do not coincide entirely, and so each has an incentive to deceive the other.
How can honest communication be ensured?
Before considering these examples, however, we will describe the general solution that signalling theory offers in answer to this puzzle.