Signals evolve only if it is in the interest of the signaller to supply that information, and only if the information thus supplied is reliable enough for the receiver to take it into account. Hence it is reasonable to assume that once the reliability of the signal is gone the signals will be selected out rather than become conventional.#
For every message there is an optimal signal, which best amplifies the asymmetry between an honest signaller and a cheater.#
A signal is reliable when the investment required for its use is greater than the potential gain a cheater would make from using it improperly.#
The reliability required in signaling militates against efficiency. Handicaps increase the reliability of signals not despite the fact that they make an animal less efficient, but because they do. Any improvement in a signal must be accompanied by a cost to the signaler – that is, must make the signal’s bearer less well-adapted to its environment.#Quoted in Chris Knight, “Puzzles and mysteries in the origins of language” (2016)
In signals, cost is of the very essence; it is necessary to the existence of the signal. If there is no cost, nothing prevents cheaters from using a signal to their benefit and to the detriment of the receivers, and that signal will lose its value as a signal.#Quoted in Chris Knight, “Puzzles and mysteries in the origins of language” (2016)