I want to talk about the awesome, yet unappreciated, power of isogloss maps. I find that a lot of people in general misunderstand Proto-Indo-European (PIE) to have been a single, unified language when in fact this could never possibly have been the case. At any given time, PIE would have been an assemblage of dialects from start to finish. Of course, when I say that, I will probably be misunderstood to have meant that the reconstruction of Proto-IE is invalid or futile, which I stress is absolutely not my position at all.
Rather I think that by conceiving of language change in a better way, as I will explain below, we can gain a lot more insight into protolanguages than is currently the norm. To me, the confusion about language evolution stems from a popular, antiquated notion of language change as represented by the all-too-famous "family tree" diagrams. We can see the concept in this picture or in this one. As the diagram implies, language divides into various new languages as time goes on much like how a tree grows new branches as it ages. This is a horrible way to understand language change.
A better way is to recognize language, not as a single entity, but rather as a package of features (whether they be grammatical features or phonetic features) that coexist within said language. Furthermore, these features may spread like waves over a geographical area much like waves in an ocean and therefore spread into other neighbouring dialects or even completely different languages. When one language affects another, dialectologists call it areal influence.
So now, if we can truly understand that languages are nothing more than the mere intersection of spoken features within a specific geographical area and that each of these features may be represented as independently spreading waves, then we can now understand what I mean when I say that PIE was never a single language and had always been a sea of regional dialects.
Now that we have that clarified, I want to explore a crazy idea. It's untested but even if it's wrong, it should give you an example of an as-yet underappreciated process using isogloss mapping to tease out interesting details about a protolanguage's history that would otherwise go unpondered. I want to posit an idea that the satem innovation of PIE was in fact caused by areal influence from a "para-dialect", that is, a dialect lying just outside the boundaries of PIE itself. A dialect, in other words, that was almost-but-not-quite PIE. One that only shared some features with PIE because it had split away at an earlier date than Anatolian or Tocharian while innovating new features. The only way I can fully explain how this intriguing idea would work is to illustrate this in a video using my skills with Macromedia Flash.
In this rough sketch presented in my video below, the p-Satem (or para-Satem) dialect is a hypothetical paradialect that could have perhaps provoked the Satem innovation in PIE. I toy with this idea to illustrate for you how language waves and isogloss maps can help us explore new details about ancient languages.
(Hopefully this video will show up because I've never used Blogger's new video feature before. Knowing how most programmers code and being pessimistic, I'm thinking that I will encounter problems as I press "Publish Post". Let's all cross our fingers that my video will be visible.)
As I expected. Unskilled programmers botch up yet another "user-friendly" service. What an annoying hassle but I'm used to fixing other people's stupid programming. So I have uploaded my presentation to my eSnips account for downloading.
Sorry for the inconvenience but blame Blogger and don't forget to send them hate mail, hehe.