ABSTRACT
The evolution of animal signals is currently a matter of some controversy. One hypothesis argues that signals typically function to communicate accurate information about subsequent behavior. An alternate hypothesis claims that signals are often attempts to mislead, bluff, or deceive and that selection has favored skeptical recipients able to detect such deception. We review evidence that bears on these hypotheses and pay particular attention to communication among group-living animals. We consider evidence that animals (a) change the meaning of signals, (b) vary the rate of signalling and thus withold or conceal information, (c) signal false information, or (d) respond skeptically to the signals of others. Field experiments on vervet monkeys suggest that animals are skeptical recipients, and that the detection of deception is determined by the ways in which animals compare signals based upon their meaning.
