Ancient History on Wheels

The secondary products revolution was a game changer in the prehistoric world, and arguably the most important invention of this period was the wheel, with great implications for mobility, trade and warfare. It was long assumed that the wheel was invented in Mesopotamia, but today scholars are instead pointing toward Europe. 

In a 2007 paper, Finnish anthropologist Asko Parpola writes:

"The very earliest presently known evidence for wheeled vehicles comes (in the form of wheeled animal-shaped cups and house models) from the Tripolye culture (phases B2 & early C1, c. 3800 BC) (Gusev 1998; Burmeister 2004: 14f.). The slide-car pulled by oxen is widely assumed to have been the predecessor of wheeled vehicles, and it too is documented from the Tripolye culture (C1 and earlier, cf. Burmeister 2004: 21f.). The Tripolye culture is located in the middle of the earliest vehicle finds, in the forest-steppe with big trees needed for solid wheels yet with plains more trafficable than the forested central and NW Europe"

In the same paper, he later writes:

"Valentin Dergachev (2002, 2007) has recently suggested that during Tripolye B1, the pastoralists of the Pontic steppes attacked Tripolye settlements on a vast scale. The number of arrowheads found in Tripolye settlements rises phenomenally, and previously unprotected settlements become fortified. Philip L. Kohl (2004, 2007: 23-54) calls attention to the subsequent transformation of the Tripolye people from settled farmers to more mobile pastoralists (Kohl 2004, 2007: 23-54). I suggest that the linguistic Indo-Europeanization of non-Indo-European speaking Europe started with Tripolye, the farming culture closest to the steppe pastoralists, who had long received their metal from Tripolye and been under its cultural influence."

The earliest evidence for wheeled vehicles outside of territories either demonstrably non-Indo-European, for example, Sumer (Uruk, 3500-3100 BC), or implausibly Proto-Indo-European – such as the Kuro-Araxes culture of south Transcaucasia where Hurro-Urartian languages appear (Arslantepe, 3400-3100 BC) – is to be found among a number of fourth-millennium BC cultures in Europe. These include the Funnelbeaker culture of Northern Europe which reveals an acquaintance with vehicles by the mid-fourth millennium BC; a famous ceramic vase dated 3500-3350 BC from Bronocice, Poland, depicts what looks like five four-wheeled carts. Clay models of four-wheeled carts from the Late Copper Age Baden culture in the Carpathian Basin, modern Hungary, are dated to 3300-3100 BC. Then there are some full-sized wooden wheels from the latter half of the fourth millennium BC, that have been found in Switzerland, Slovenia and Northern Italy. Numerous remains of wheeled vehicles in the Pontic-Caspian region also emerge towards the end of the fourth millennium BC. Most impressive of all, there are remains of complete wagons from the Caucasus Novotitorovka culture in Georgia, dated about 3500 BC.

Linguists Tomas Gamkrelidze and Vyachislav Ivanov have noted that one of our words associated with wheeled vehicles, Proto-Indo-European *kwekwlo-, bears striking similarity to the words for vehicles in Sumerian gigir, Semitic *galgal-, and Kartvelian *grgar. With the putative origin of wheeled vehicles set variously to the Pontic-Caspian region, Europe, Transcaucasia or to Sumer, we may be witnessing the original word for a wheeled vehicle in four different language families. Even the Chinese bears some similarity, with the Mandarin being gulu and the Cantonese gukluk. All of this suggests at least a connection.

The argument is that the technology of the cart was so marvellous that it spread rapidly across Europe and Eurasia – perhaps assisted by the fast horses tamed by the steppe pastoralists who had invaded the Tripolye culture. As the Proto-Indo-European *kwekwlo- is built on an Indo-European verbal root *kwel- ‘to turn, to twist’, it is unlikely that the Indo-Europeans borrowed their word from one of the other languages. In addition to *kwekwlo- and *kwel-, scientists have reconstructed at least two more Proto-Indo-European words for wheel, as well as words for axle, thill, yoke, nave and a verb meaning ‘drive’ or ‘convey in a vehicle’.

The notion that Mesopotamia was the birthplace of the wheel is a claim that has lost its legitimacy over the years. Wheeled vehicles are attested earlier elsewhere, although the Mesopotamians are still likely candidates for being the inventors of the potter's wheel.
The findings in the last decades instead point toward an introduction of the wheel *to* Mesopotamia. The spoke-wheeled chariot and horse was diffused to Mesopotamia as well, some time later on. Furthermore, the speakers of Proto-Indo-European demonstrably invented their own terminology for wheels and wheeled vehicles in the 4th millennium BC, notably the word *kwekwlo- (wheel) derived from the verb *kwel- (to turn).

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Attached: Artifacts from two contemporary Indo-European Bronze Age cultures, Urnfield and Nordic Bronze Age, featuring what could be interpreted as sun crosses, stylized wooden shields, or wheels.

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References:

Asko Parpola, Proto-Indo-European speakers of the Late Tripolye culture as the inventors of wheeled vehicles: Linguistic and archaeological considerations, 2007. https://www.researchgate.net/publication/241387355_Proto-Indo-European_speakers_of_the_Late_Tripolye_culture_as_the_inventors_of_wheeled_vehicles_Linguistic_and_archaeological_considerations
J.P. Mallory, In Search of the Indo-Europeans: Language, Archaeology, and Myth, ISBN 050005052X, p. 163. 
John Farndon, The World's Greatest Idea, ISBN 1848311966, p. 95.