An alternative theoretical account has recently emerged. The theory of honest signalling (or 'costly signalling') shows that individuals may find some interest in signalling some of their qualities, even if such a display is costly for them and beneficial to others (Gintis et al. 2001). By means of computer simulations, we showed that language performance could evolve as a display mechanism, offering a reliable criterion for choosing coalitions partners (Dessalles 1999). What the model shows is that whatever individual quality that is positively correlated with coalition success will be displayed by individuals. Informational ability is such a quality: by talking, individuals make endless attempts to demonstrate that they know before and better than others. In other words, we happen to talk because we are a 'political species', where individuals must form coalitions to be successful or merely survive. Unlike other primate species, human alliances are large enough for information to play a significant role, replacing in part the role of physical strength. As a consequence, rather than making efforts to show their muscles, human beings of both sexes take any opportunity to show their informational abilities through language (Dessalles 2000).
Dessalles, J-L. (1999). "Coalition factor in the evolution of non-kin altruism". Advances in complex systems, 2(2), 143-172.
Dessalles, J-L. (2000). Aux origines du langage - Une histoire naturelle de la parole. Paris : Hermès.