In fact, languages evolved like species. Something became something that's no longer present, and which is usually more efficient / adaptable than what was before it.
That's a view of language change which resembles the Stammbaumtheorie, which was put forward by August Schleicher in the 19th century. Schleicher tried to apply scientific insights from biology, more specifically the field of botany, to linguistics. While his model is still considered influential, language change is much more complex than that. In fact, most of the changes that occur in languages have nothing to do with "efficiency" or "adaptibility". For example, the fact that the early speakers of Germanic began to realize Proto-Indo-Germanic plosives as fricatives cannot be explained by these terms at all. To put it in other words, we know that all languages change over time but we usually have no clue why this happens.
Well, there are sociological factors behind the evolution of language, I would think. A language has to be malleable in order to continue and of course it has to be the language of the dominant culture(s).
Language has to adapt to reflect cultural changes as well as technological changes and probably other things beyond that. In any event, my point was that it was not created "as is" and generally adapts to serve the people who use it.
