We develop Deacon’s (2010) proposal on the role of relaxed selection in the evolution of human language, providing a sound evolutionary background for it, within the human "Self-Domestication" hypothesis (Gibbons, 2014). We focus in particular on neotenic features of life-history traits and brain development, characteristics of modern Homo sapiens, suggesting that they could have spread in an ecological context in which some selective pressures were relaxed. We give an account of how such an ecological condition could have been reached in hominid evolution, relying on the feedback effects of niche construction processes, bringing the case of the use of fire. We provide some future possible directions in order to make our hypothesis testable, suggesting it could help solving some issues concerning human evolution and the evolution of language.
Keywords: Exaptation, Language evolution, Neoteny, Niche construction, Relaxed selection, Self-domestication.