Pace Anthony, the problem is slightly more complex.
First, the Anatolian languages have to be excluded. Apart from Hitt.
hissa- `draft pole', which may be related to Slavic *ojes- and/or
Skt. i:s.a:, vehicle technology is not much in evidence there; even
the Anatolian `horse' words look like loans from (Mitanni) Indo-Aryan.
Secondly, there is no single term for `wheel' or `wagon' in non-
Anatolian IE, but rather clusters of lexemes derived from a small
number of roots: the wheel word is either *roth2-o-/-ah2 or *kWekWlo-
, the latter with branch-specific variants; `wagon/cart' words are
_various_ independent derivatives of *weg^H-e- `carry' (used also of
water, wind, boats, etc.). The horse (*[h1]ek^wos) was no doubt known
to speakers of ancestral non-Anatolian IE, but the word may also have
referred to wild horses.
I don't believe in unconstrained diffusionism a la Renfrew, but the
genetic unity of vehicle vocabulary is partly an illusion resulting
from a selective approach to linguistic data (ignore Anatolian,
ignore lexical and derivational variation ...). My guess is that
wheel transport (ox-drawn carts and wagons) was adopted by the IEs at
a time when the non-Anatolian IE languages still formed a relatively
homogeneous block -- presumably a dialect continuum small enough for
innovations to be propagated without much difficulty but leaving room
for quite a lot of regional variation.
The dates offered are definitely too shallow, just as Renfrew's are
too deep. The end of Indo-Iranian unity must be dated ca. 2000 BC or
slightly earlier (a convenient dating if we want to credit the Indo-
Iranians with the invention and dissemination of horse-drawn
chariots. Sufficient time is also needed to account for reconstructed
earlier events and the degree of differentiation evident by the mid-
second millennium.
During the period 3600-3000 BC wheeled vehicles appeared in various
places from Germany to Uruk and Central Asia (the place where the
invention took place is a matter of debate), and a good part of that
area was likely settled by people speaking partly differentiated Indo-
European languages. My (tentative) view is that the beginning of the
fourth millennium BC is the most likely terminal date for _non-
Anatolian_ IE unity.
Piotr
--- In cybalist@..., naga_ganesan@... wrote:
> The IE intrusion into India, in the times of post-Indus culture
> decline has not much to do with the glacier melts 12800 BP.
>
> The IE expansion from the homeland is after the wheeled transport
> technology was invented and before chariotry. Prof. David Anthony
> (Archaeology dept., Harvard university) publishes that the wheels,
> vehicle technology could have been invented by others. (Archaeology
> shows the inventions in the Near East). But at the time of
invention
> of wheels, vehicle technology, PIE existed as one single community.
> This is after 3500 B.C.
>
> David Anthony, Shards of Speech, 1995, Antiquity, v. 69
> "Terms for wheel, axle and draft pole, and a verb meaning 'to go or
> convey in a vehicle' suggest that PIE existed as a single language
> after 3500 B.C., when wheeled vehicles were invented. PIE must have
> begun to disintegrate before 2000 B.C.: by 1500 B.C. three of its
> daughter languages - Greek, Hittie and Indic - had become quite
> dissimilar. Altogether, then the linguistic evidence points to a
> homeland between the Ural and Caucasus mountains, in the centuries
> between 3500 and 2000 B.C." ...