Hi David! Sorry for bothering again (again). A conlanging question this time: Every time you talk about creating languages you mention the process of evolving the conlang and how it gives it a more natural feel. My question is: How do you evolve your langu

This is a question that really only a book can answer. I’ll try to give you the bullet points of an executive summary of an introduction to the topic.

Languages change in three main ways:

Sound Change: The sounds of a language will evolve over time. This is why “says” sounds like it should be written “sez”.
Lexical Change: Words change meaning over time. A word like “obnoxious” originally meant “liable to be injured”. It means nothing of the kind of anymore, though.
Grammatical Change: The grammar of a language also changes over time. We now have two different future tenses (three if you count “shall”), none of which originally meant “future” (one meant “go”, the other “want”, and the other “to have to”).

I’ve listed these in, roughly, order of simplicity, when it comes to conlanging. For sound changes, there are undoubtedly a number of resources online that summarize the most common sound changes and how they work. There are also sound change appliers online that will take your input and apply sound changes you create to them. It’s worth a look.

Lexical change can be tricky. Pretty much any word is liable to be changed (i.e. it is obnoxious to change. Heh, heh…), but not all words will. It’s up to the conlanger to figure out where changes will occur and where they won’t, and what words will arise to fill the gap, if any (for example I can’t think of single word that has the old meaning of “obnoxious”. We just lost that. Now we have to explain the meaning).

Grammatical change affects mainly paradigms. For example, Latin had a way of creating adverbs from adjectives, but for some reason Romance pretty much ditched it, replacing it with a combination of “adjective+mind” (e.g. Spanish rápido = fast; rapidamente = quickly). You can see how wholesale grammatical restructuring happened from Latin to Romance with the loss of pretty much all noun case, the development of articles, and the shifting of the verbal system. In order to do this in a conlang, you basically need a more or less fleshed out older language and to apply the same types of changes (appropriate, of course, to your time depth. A language changes a lot less in 300 years than it does in 3000).

Again, this is really just scratching the surface, though. If you’d like a couple of resources, I recommend Lyle Campbell’s Historical Linguistics and Bybee et al.’s The Evolution of Grammar.