Originally Posted by
Montmorency
For IndoEuropeans, by the time of their wide-ranging migrations 7-6,000 years ago their language had likely already been undergoing the process of simplification since the beginning of the Neolithic. Prior to the migrations, we can imagine that the overall population size of their culture was no more than 100,000 at any point, perhaps much less.
It makes sense if you consider early languages to have come about through a hodge-podge of ad-hoc additions and accommodations based on semantic/cognitive ways of organizing the world for those pre-historic humans. To work an answer to Viking into this: consider that complexity of form and complexity of function correlate more-or-less inversely. In the modern world, say in the modern-English-speaking urban environment, world-knowledge and communicative requirements are orders of magnitude higher than for prehistoric societies. In other words: high complexity function, low complexity form. Meanwhile, the "kludgeocracy" of form-complex (i.e. the grammar and phonology in themselves, independent of any specific usage) pre-historic language would have served a socially-integrative role as well as being basically adequate for communication of low-complexity knowledge and information. Consider the difference between a modern person having to switch between social registers and dialects depending on context, trying to explain to their boss that their cousin was hurt in a car-crash and they have to visit them in the hospital because of insurance issues, and they won't be able to come to work today but can work overtime next week to make up for it, versus a tribal leader explaining to the children over the campfire how man was created from the earth by star-beings and yadda-yadda. The point is, in the societies I'm talking about there are relatively-few negative consequences to the high cost of complex form - because the functional usage of the form is comparatively simple compared to much of the modern world.
As for the future, I'm sure language will have a very different appearance. It will probably simplify, for sure, once governments realize that most syntax - even now - is not strictly necessary for communication, and will enforce policy to strip it down to utilitarian standards. This will also interact with the widespread direct modification of the human language faculty through genetic and neurophysiological manipulation in as-of-yet unknown ways.