Somebody suggested to me recently that languages always develop towards simplicity. It is not unusual for people to think that. There is a popular opinion out there that languages start out as very complex but over time the grammar and vocabulary and pronunciation and everything becomes more simple.
First of all, any talk of complexity and simplicity assumes that we can actually define and measure what complexity and simplicity is. Mostly, when people claim that a language is simple or complex, they mean it in comparison to their first language or to some other language they already know well. I don’t know if there is a truly language-independent way to measure complexity, but let’s assume for a minute that there is.
So, do languages develop over time towards this ideal of simplicity? I tend to disagree with that. Sure, languages are always developing, but they’re not always marching straight ahead towards greater simplicity. In fact, it is not unusual for a language to become more complex over time.
One place where we can observe this is its vocabulary. Everybody would probably agree that a language that has just one word for a given concept is simpler than one that has an abundance of synonyms. But then look at a language like German: many concepts are denoted in German by a pair of synonyms, one of Latin origin and another of Germanic origin: Humanität and Menschlichkeit (humanity), Toleranz and Duldsamkeit (tolerance), Adresse and Anschrift (address), and so on. When the concepts these words denote entered the German language, they become lexicalized in two different ways. Exactly why or how it happened is irrelevant: what’s relevant is that it did happen and German speakers now have one more thing to worry about than they need: they need to decide in each case whether it’s appropriate to use the formal Latin term or the homely Germanic term. It’s an extra level of complexity which has been introduced into the language during its history. So here we have an example of how a language has developed from simpler to more complex.
Vocabulary is not the only place where we can sometimes observe a language developing towards greater complexity. It’s uncontroversial to say that English orthography is a mess. There is no clear correspondence between the way words are spelled and they way they are pronounced. It has come to be this way because of the changes in pronunciation that happened while the written version remained unchanged. So again, here is an example of a language that has developed towards greater complexity.
To my mind, a language is like an old building that has been rebuilt and extended again and again over the years. It has lots of old wiring and plumbing in it which is too complex for anybody to understand anymore, it is certainly more complex than anybody would have designed it from scratch, but it works and so people prefer not to meddle with it.
In fact, all systems that have developed over time invariably end up being more complex than they need to be. This applies to everything including old buildings, cities, living organisms, ecosystems, companies and even computer software. It is naive to believe that evolution always produces perfectly tuned-up systems. Evolution actually has a habit of re-using existing structures instead of inventing new ones, thus shlepping baggage along that sometimes introduces unnecessary inefficiencies. Language evolution is no exception.