I’m back at Chaco and giving tours again, so I’m once again being exposed to visitors’ common questions and preconceptions in a way I haven’t been in a long time. One thing that seems to surprise a lot of visitors is the fact that the Chacoans apparently had no knowledge of the wheel, or if they did have such knowledge they didn’t apply it to transport any of the many things they brought into the canyon from distant sources. (People are also sometimes surprised to learn that they didn’t have draft animals either, which I find a bit surprising myself since I tend to think of that as common knowledge.)
I think it’s actually not difficult to see why the Chacoans wouldn’t have seen any use for the wheel even if they somehow knew about it, and the lack of draft animals is the key to understanding why. (This is admittedly a bit speculative on my part, but I think it works.) Without big, strong animals to pull wheeled vehicles, any efficiency gains from them in terms of human labor would be decidedly non-obvious. The only type of wheeled vehicle that would really be effective using only human labor would be the wheelbarrow, and while this may provide some efficiency gains over carrying goods by hand I don’t think they would have been clear enough to compensate for the increased effort involved in building the thing, especially given the often rough and broken terrain of the Southwest. Even the Chacoan roads, which may or may not have actually been intended for use in transporting goods but certainly could have been so used once they were built, were actually not as level and easy as people often assume, although they were more level than the surrounding terrain. Most of the effort put into the roads went into clearing the surface and defining the curbs, but grading of the cleared ground surface was typically not done and the road beds follow the underlying terrain for the most part. This was fine for foot traffic, and definitely an improvement over the uncleared surrounding terrain, but it wouldn’t have been particularly suitable for wheeled vehicles. Furthermore, the vaunted straightness of the roads would actually have made them even less suitable for wheeled vehicles or draft animals, given the common practice of handling steep cliffs in the path of the road with stairways. Good luck getting a cart up or down one of those!
The lack of draft animals and the unevenness of the terrain have also been posited as reasons for the lack of wheeled vehicles throughout the Americas. While the terrain would not have been an impediment everywhere, such as in the Yucatan where the terrain is generally flat and the roads built by the Maya were much more elaborate and level than anything seen around Chaco, in highland areas like Central Mexico and lowland areas covered by dense vegetation such as those along the Gulf Coast of Mexico the maneuverability of a person on foot would likely have been far more important to efficient transportation than any increase in efficiency resulting from wheeled vehicles in the absence of animals to pull them. Gordon Ekholm of the American Museum of Natural History, whom we last saw discovering atlatl finger loops, discussed many of these issues in an interesting article from 1946 about the wheeled toys found in various parts of Mexico, which demonstrate that at least the Mesoamericans were in fact aware of the wheel even though they didn’t use it for any practical purpose. These clay toys, in the form of animals with wheels in place of feet, had been found in widely scattered parts of Central and Northeast Mexico, from Oaxaca to Veracruz, and while the axles connecting the wheels to the feet were apparently made of a perishable material like wood and did not survive, the fact that one example was found in situ with the wheels in the proper position led Ekholm to conclude that they definitely were originally wheeled. Robert Lister (a very prominent figure in the history of Chacoan archaeology who also did some work in Mesoamerica) followed up on Ekholm’s article shortly afterward, noting the apparent presence of similar wheeled toys in West Mexico and referring to the discovery of copper examples in Panama as well.
Ekholm’s article provides a solid discussion of the implication of these toys for Mesoamerican technology and general anthropological understanding of technological development. He discusses the lack of draft animals and the difficult terrain, but ultimately concludes that the main factor preventing more widespread use of the wheel was likely a cultural and technological conservatism that privileged the old way of doing things, which in this case meant carrying goods on people’s backs, over an untried new invention like the wheel. He attributes the origin of the idea of wheeled toys to pure invention, probably stemming from experimentation with the round spindle whorls that are very common Mesoamerican artifacts. It’s not clear just how far this idea spread, and to my knowledge there is no evidence that anyone in the Southwest was aware of it, although some of the ceramic animal effigies found at Chaco and elsewhere do bear some resemblance to the Mesoamerican toys. Ekholm makes a convincing case that despite the ingenious nature of these toys, without suitable social and ecological conditions for the wider adoption of the technology it remained more of a curiosity than anything else.
Basically, without draft animals, the idea of making a big vehicle like a cart which could carry a heavy load more efficiently than a person could would be unlikely to have occurred to anyone, because such a cart would still have to be pulled by people. Or, in other words, if you have a cart but not a horse, you are, well, putting the cart before the horse. And who would do a thing like that?
Ekholm, G. (1946). Wheeled Toys in Mexico American Antiquity, 11 (4) DOI: 10.2307/275722
Lister, R. (1947). Additional Evidence of Wheeled Toys in Mexico American Antiquity, 12 (3) DOI: 10.2307/275708