Though it is well-known that nothing makes sense in biology except in the light of evolution, in linguistics the received view is to reject the Darwinian approach. This book breaks the prevailing taboo and argues instead that linguistic features - speech sounds, grammatical distinctions and syntactic strategies - have followed an evolutionary course. Though variation exists and gratuitious changes can be found, an in-depth study clearly suggests that on the whole linguistic features have developed under two sets of selections pressures: the pressure to reduce the neuromuscular cost, and the concomitant pressure to find ever-more functional alternatives. Moving on from language to writing, the author argues that the observed optimalization process also applies to the evolution of writing from hieroglyphs to alphabets. Both language and writing are indeed better understood in the light of evolution.