Language Change and SVO order

McMahon says that languages 'can be classified genetically (...),areally (...),and typologically [that is accordingly to their internal features]' (p139). Then he (or she) says that typological classification, which was in the focus of the last lecture, 'covers all areas of grammar: the phonology [the sounds of language [-see IPA alphabet http://www.langsci.ucl.ac.uk/ipa/ipachart.html ] , morphology [ http://www.britannica.com/EBchecked/topic/188048/English-language/74801/Morphology ], syntax, [http://www.merriam-webster.com/dictionary/syntax] , semantics http://en.wiktionary.org/wiki/semantics ], and vocabulary' (ibid) -the links for non-linguistic students. What is our interest is morphological and syntactical typology (as morphology influences syntax and may influence the word order).In 1920' Sapir suggested that there is a drift in all languages, that is they change 'move down time' (p138). The drift, a bit biological term, refers to evolution of languages. Later on Greenberg (1960s) carried out a research to find language features universal for most or possibly all languages. His database of 30 languages researched expanded through the years to 600 languages nowadays.  His findings, quite consistent, were based on SVO order and other elements of syntactic structures within the sentences. He found that languages structures  tend to fall into one of the patterns:
VSO - Preposition - NG - NA  (N=noun, G=genitive, A=adjective)
SVO - Prepo - NG - NA
SOV - Postposition     GN - AN
SOV - Post- GN - NA
(p 142)
Later on Lehman & Vennemann (1970s) modified the findings:
(when we eliminate S, we can collapse it to two patterns:)
VO - Prep- NG - NA
OV - Post - GN -AN

What Lehman and Vennemann found interesting is that whatever pattern of SVO order is adapted by language, the language will follow the rules that are consequent for this pattern structure. So the SVO languages will tend to have head - modifier order:
for the example see p 143.
modifier:http://en.wikipedia.org/wiki/Grammatical_modifier
genitive :possessive: serving to express or indicate possession; "possessive pronouns"; "the genitive endings
Lehman and Vennemann called this linguistic principle as 'the principle of natural serialisation'
The idea is not to get bogged out with grammatical terms really but just to get what happens if language has the tendency to shift from one word order to another.SVO languages have a very strict word order (so has English); however, the inflecting languages have flexible word order (and we know English belongs to family of inflecting languages...). L & V pointed out that the language in certain SVO order will keep the word order of the whole sentence in harmony for this order. This may have very complicated meaning, but what it seems is that the SVO (SOV or whatever different structure the given language has) is there for a reason. We order words in certain way to convey meanings during communiction. We still have bear in mind what are the basic functions of every language, and the main function is to communicate, that is to express the meanings as precisely as the language allows us to do so (and our linguistic skills or lack of them :) ) We stick to the order that is understood in the speech community. (another function) SVO order in English conveys the clear message understood by other members of the community, if we change it, the msg may not be clear (even though understandable)
I like sleeping. (SVO)
I sleeping like (SOV) ... not clear.

However, there are 'drifts' in languages and 'languages may become inconsistent due to  shift in word order'
So how does the shift happen? What triggers the shift?
I guess many of us has seen the Star Wars. Have you noticed Yoda's language?:

Watch : YODA'S SYNTAX (youtube)
'Careful you must be'
'Begun the . . .war has'
'Wonderful the mind of the child is'
'Powerful you have become'

Read more about Yoda's syntax

So we do change the order e.g. for stylistic reasons, and often in poetry :
There is a difference between:
and stood she there, sad and unhappy
and she stood there sad and unhappy

And they say we had inverted SVO order in old English:
http://everything2.com/user/izubachi/writeups/Old+English+Word+Order
So as the Star Wars language is rather a subject of jokes or language play and it does not exist in common language ( I am not trying to imply that English undergoes word order changes influenced by Yoda here!) but it is undusted like, appeared for awhile and was 'seen' and noticed' by many. It could stay or it could go, it could become part of our every day life speech or not. Maybe.

As above, word order is there for a reason of clear communication. L & V suggested that if language goes through the word order shifts, the 'rest' of the language (grammatically) will be used to balance the harmony. The harmony? Ambiguity. The constant drive of language is to avoid or minimize the ambiguity, therefore, in each language we (they say) can find markers, clues, elements that exclude some of the ambiguity.
So it looks like whenever we try to look at language change we have to remember about its functions first.
I heard people saying:  I done it. She been there.It violates the svo order, however,we still can recognise the perfect context of the sentence because they use past participle.If we said: I worked - we cannot mean there I have worked by no chance, as there is ambiguity. Let's say we suddenly start using this structure, according to L &V the language would automatically like travel towards finding certain markers to diminish the ambiguity. (If I got it right). Probably Labov and his study on Black English Vernacular (omission of to be) could give us some clues.
So the result seems to be : No matter what we do with the language it still has to be functional. And on top of it, it isa  universal feature, that goes across all languages.As languages are alive, created/used by the living people for their purposes.
This is how I got it. I might be slightly off the subject with this Yoda business... but I found it easier to understand.