We may assume that the greater the temporal distance, the greater the differences in linguisticity. In the short term, differences may be hard to distinguish, but in the medium- to long-term, differences monotonically increase over time. In the extreme, we may not even recognize the differences as being part of linguisticity at all. Nonetheless we assume that they are related.
We also assume that the character of short-term changes has itself changed over time. If we divide time into ten thousand year epochs, then during each previous epoch there may have been changes in the fundamental character of the linguisticity of the human or proto-human population. To describe the changes between any pairs of more recent epochs, we might require a different sort of observational language. Whether there could be a general theory that covered the dynamical character of both examples may also be doubtful. One may have grammatical categories that the other lacks, for example. Certainly, over a sufficiently long period there would be no reason to suppose that the grammatical categories were the same.
Derek Bickerton's [10] research into language evolution has led him to believe that some evolutionary traits have emerged by radical steps towards the use of language from proto-language - loosely put, a language without a syntax. In his view proto-language lacks the grammatical components that a natural language does.
In this case, the grammatical categories that describe proto-languages are absent and there is a marked difference between the description of Bickerton's proto-language and natural language. This would suggest that not all evolutionary increments are achieved at a regular slow pace and also the increments are quick, fairly large steps that do not involve intermediate ones.
A theory of sudden evolutionary changes for a biological phenomenon, such as the developments towards our linguisticity, does not sit well with traditional evolutionary theories and idiom. However, Bickerton is not alone in his assumptions, Stuart A. Kaufman has suggested similar jumps in genetic evolution[37]. Both have had to borrow from several idioms to explain their views.
This thesis uses a similar strategy. We will borrow from physics to describe behaviors in the evolution of language that could be understood as sudden changes in linguisticity. Moreover, we will suggest physical models that account for the behaviors.
The language of a theory of language may have to change with major changes in the language itself. A theoretical language of sufficiently high order, such that it might be applicable to language at all stages of its evolution may be practically inaccessible. And we might find nothing to say.