Evolutionary adaptation in variable environments is likely to give rise to several signals that can be used to identify a suitable mate in multisensory organisms. The presence of multiple signals for sexual selection could be advantageous, limiting the chance of mating with a suboptimal partner and avoiding the costs of inferior progeny. Despite extensive research into isolated signals of attractiveness, the amalgamation of multiple signals in sexual selection is poorly understood, particularly in humans. Inferences regarding both the function and importance of such signals are therefore tentative unless the effects are considered together. Here, the literature regarding two evolved signals of attraction (cf. faces and voices) is reviewed in relation to a framework (Candolin 2003) for signal integration. It is argued that the functional nature of signals of attractiveness would be better studied through manipulation and experimentation with both single and multiple signals. Considering the prevalence of traits in relation to their combined effects may well provide a more fruitful and informative approach to human mate selection.
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