The Horse, the Wheel, and Language

David Anthony's book by this title is about the search for - and ways of life of - the original speakers of Indo-European, the tongue ancestral to languages spoken by about three billion people today. Both his account of the detective work and his conclusions are highly impressive.
Anthony is unusual in that he combines his training in archeology with a great familiarity with historical linguistics, which allows him to bridge normally distinct fields and to piece together disparate clues about the original Indo-European speakers. I was continually struck by just how much work has already been accomplished in each of these disciplines. For example, historical linguists, by comparing extant Indo-European languages and relying on rules of language change, have developed a vocabulary of several thousand words (!) from the mother language, even though it was spoken between perhaps 4500 and 3500 BCE and never recorded in writing. Even more impressive in some ways was the sheer attention devoted by archeologists to these archaic cultures. Hundreds, and even thousands, of sites from each of dozens of different cultures living around the Black and Caspian Seas (and no doubt elsewhere) have been thoroughly studied and catalogued. So a basic impression for me was the same one I got when I read Stephen Pinker's book How the Mind Works: namely, astonishment at just how much we do know. It's amazing what our economic surplus and academic specialization have permitted. This may sound trivial, but it provides a useful response to a common refrain I hear: we just don't know enough about X to take a stance one way or another. My friend James resorts to this tactic whenever we discuss evolutionary psychology. Because it sounds plausible (the brain is complicated, after all, and early man did leave few traces, so how much do we really know about it anyway?), this is often an effective way not to rebut the other side, but to end the discussion nonetheless. My readings of Pinker and Anthony make me even more resistant to this response.
So what are some of Anthony's substantive conclusions? The speakers of Indo-European were foragers living in river valleys north and west of the Caspian and Black Seas. They likely adopted cattle, sheep and goat herding from peoples living on the west shores of the Black Sea circa 5000 BCE. (These latter peoples, by the way, living along the lower Danube and east of the Carpathians, had the most advanced metal-working and the largest settlements *in the world* between 4000 and 3500 BCE. It never became clear to me why this region was so advanced.) Around 4000 BCE, the Indo-Europeans probably became the first people in the world to domesticate the horse. By perhaps 2000 (or was it 3000?), they had imported the wheel from the Near East (at first a solid wheel, useful only for slow-moving, ox-drawn carts, later, modified by the Indo-Europeans to include spokes, part of the revolutionary war-chariot).
The domestication of the horse and the importation of the wheel changed everything. The former allowed much larger herds of animals to be controlled. In addition to a general increase in wealth, this led to the emergence of significant social status differences (deciphered mainly by new burial practices) and various related social and political practices. For example, contractual relations developed when more marginal herders were compelled, by bad luck or having lost parts of their herds to theft, to borrow from wealthier herders. The wheel (in the form of ox-drawn carts) allowed the Indo-Europeans now to range much more widely over the steppes, since they could bring provisions with them. This more nomadic life - along with the temptations posed by cattle-rustling - led to the development of various host-guest practices. Nomadic groups learned to distinguish between acceptable visitors passing through their land (guests) and hostile interlopers. Anthony argues that Indo-European spread - into Greece, up the Danube and Dniester, then to the east, all the way to the Altaic Mountains, and also down into Iran and India - only partly by military conquest (facilitated by horseback riding). Even more important was the economic power and status these wealthy herders enjoyed. These factors convinced neighboring peoples to convert to a new way of life and language.