Most natural languages have a predominant or fixed word order. For example, in English, the word order used most often is Subject-Verb-Object. This work attempts to explain this phenomena as well as other typological findings regarding word order from a functional perspective. That is, we target the question of whether fixed word order gives a functional advantage, that may explain why these languages are common. To this end, we consider an evolutionary model of language and show, both theoretically and using a genetic algorithm-based simulation, that an optimal language is one with fixed word order. We also show that adding information to the sentence, such as case markers and noun-verb distinction, reduces the need for fixed word order, in accordance with the typological findings.