...there isn't a simple mechanism which favors that change (OV->VO) ... [Jon Aske]

Jon Aske dá hizkuntzalari euskaldun bat, zeinek bere tesian landu zuen euskararen hitz-ordena:

In my dissertation on Basque word order (UC Berkeley 1997) I proposed a solution for the "original" predominance of OV order as well as for the predominance of OV > VO shifts over VO > OV shift.

Jon Askek, erantzunez a Newsmeyer, ematen dizkigu azalpen hauek:

There is a strong correlation between grammatical subject and topic, on the one hand and grammatical object (when there is one) and focus. Indeed, the category subject seems to be but the grammaticalization of the category topic (although not all subjects are topics, and some are indeed foci).

non agerikoa baita planteamendu funtzionala. Askek dio:

The focus element, besides being accented, typically goes either in
(1) F1 position: Right before the verb, which is also rheme-first position, only preceded by any settings there might be, including a phrasal topic; or it goes in
(2) F2 position: Right after the verb (rheme-second position); or finally
(3) It may also be "bumped" to the end of the rheme, or "dislocated" to the right, as it were, into an intonation unit of its own (not to be confused with so-called "right dislocation" in English, which is really an antitopic construction).

Gero erakusten digu nolako sinpleak izan daitezken klasifikazioak:

Languages fall into two basic types:
Type 1: those which place the focus constituent consistently in F1 position (right before the verb), and never in F2 position, (so-called OV languages); and
Type 2: languages which place the focus constituent either in F1 position (right before the verb) OR in F2 position (right after the verb), depending on the construction and depending on the degree of salience, or focality of the focus in the assertion. More focal foci go in F1 position and less focal ones in F2 position. (Focus bumping is a possibility in either language type, though it may be rare in some rigid Type 1 languages).

Horrela, konsidera genitzake hurrenko hiru hizkuntza-mota hauek:

1. : Hizkuntza OV zurrunak nola japoniera, non fokua soilik kokatu ahalko da aurre aditza.
2. : Hizuntza OV malguagoak nola euskara, non lehenetsi ohi da aukerá F1 (batez ere foku laburretan), baina non den existitzen F2 ere, nahiz den gutxiago erabilia eta markatuagoa; izan ere, euskara estandarrean soilik dugu F1 aukera eta salbuespentxo batzuk.
3. : Hizkuntza VO klasekoak nola gaztelania, non den lehenesten F2 aukera, nahiz orobat existitú F1: tipo honetan F1 izaten dá erabilera aski markatua, aski adierazkorra, eta aski enfatikoa.

Zergátik jotzen dute sintaxiek an norabidea: 1 → 2 → 3? Askek erantzún:

So, why is OV > VO order change more common than the inverse:

1) I believe that there is a relatively simple mechanism for the development of an F2 position in a Type 1 language, namely through the gradual overuse of the strategy of focus bumping to an intonation unit of its own following the main assertion.
...
2) I believe that losing an F2 position ("VO > OV"), that is, losing a contrast, is a much less common change because there isn't a simple mechanism which favors that change and perhaps also for unknown cognitive reasons.

Edo Askek bere tesi-laburpenean dioenez:

The increasingly liberal use made of this latter focusing option by many speakers suggests that perhaps it is becoming relatively unmarked. I believe that this may be leading to a reanalysis of the extraposed position as postverbal for some speakers. This might explain the historical change from OV to VO as consisting of the acquisition of a new focus position, with the concomitant specialization of the positions. The opposite change from VO to OV order, on the other hand, would involve the loss of the postverbal focus position, a change which is quite rare in language.

Dudarik gabe, eta finean, asimetria horren arrazoiak dirá komunikatiboak. [85] [⇶] [A26] [A27] [A27B] [A15] (EZ [A28])