Language change usually does not occur suddenly, but rather takes place via an extended period of variation, during which new and old linguistic features coexist.
[1] Modern linguistics rejects this concept, since from a scientific point of view such innovations cannot be judged in terms of good or bad.
[2][3] John Lyons notes that "any standard of evaluation applied to language-change must be based upon a recognition of the various functions a language 'is called upon' to fulfil in the society which uses it".
For example, when we hear the word "wicked", we automatically interpret it as either "evil" or "wonderful", depending on whether it is uttered by an elderly lady or a teenager.
The orthographical practices of historical writers provide the main (indirect) evidence of how language sounds have changed over the centuries.
The degree to which the Neogrammarian hypothesis is an accurate description of how sound change takes place, rather than a useful approximation, is controversial; but it has proven extremely valuable to historical linguistics as a heuristic, and enabled the development of methodologies of comparative reconstruction and internal reconstruction that allow linguists to extrapolate backwards from known languages to the properties of earlier, unattested languages and hypothesize sound changes that may have taken place in them.
The pre-print era had fewer literate people: languages lacked fixed systems of orthography, and the manuscripts that survived often show words spelled according to regional pronunciation and to personal preference.
Conversely, the word "wicked" is undergoing amelioration in colloquial contexts, shifting from its original sense of 'evil', to the much more positive one as of 2009[update] of 'brilliant'.
"[11] The sociolinguist William Labov recorded the change in pronunciation in a relatively short period in the American resort of Martha's Vineyard and showed how this resulted from social tensions and processes.
Using weighted least squares regression and a sliding window approach, they show that, as time passes, words, in terms of both tokens (in text) and types (in vocabulary), have become longer.
[14] For prehistory, Forster and Renfrew (2011)[15] argue that in some cases there is a correlation of language change with intrusive male Y chromosomes but not with female mtDNA.
They then speculate that technological innovation (transition from hunting-gathering to agriculture, or from stone to metal tools) or military prowess (as in the abduction of British women by Vikings to Iceland) causes immigration of at least some males, and perceived status change.
Then, in mixed-language marriages with these males, prehistoric women would often have chosen to transmit the "higher-status" spouse's language to their children, yielding the language/Y-chromosome correlation seen today.