>>10
Actually, I phrased that pretty badly. Once there's an archetype, things just fall into place a certain way, possibly just due to how the brain patterns information. For example, languages with SOV word-order tend to have articles and such appended to the end of what they modify. In Latin and Turkish, this took the form of sticking conjugations onto the end of things. In Japanese (also SOV), it's about sticking particles as post-positions to perform the same functions. Also, in SOV, adjectives and adverbs tend to come before what they modify. It's just a general tendency observed over a number of languages, related or otherwise.
Chomsky theorized that this was a side-effect of how the brain parses and catalogs information, and that, in a developing brain, once a "switch" was thrown in one direction, it simply followed naturally that other switches would follow its lead, due to the information-processing system in the brain.