Sherry Towers

Sherry Towers

A millennium ago, the Pueblo peoples were constructing incredible monuments and cities throughout the US Southwest. Among the most impressive structures they left behind is called the Sun Temple, in what is now Colorado's Mesa Verde National Park. Probably the location for meetings and ceremonies, the Sun Temple is an enormous D-shaped building with walls that were once 11-15 feet high. Now, an applied mathematician has discovered something intriguing about the proportions used to lay out the temple and its internal structures.

Physicist Sherry Towers is part of the Mathematical, Computational, and Modeling Sciences Group at Arizona State University, and she occasionally takes time away from physics to focus on the way mathematical patterns shape the social world. She got interested in the Sun Temple site because many archaeologists believe its structure might reveal whether the Pueblo peoples were using it for astronomy. But as Towers pored over satellite images of the area from Google Maps, the Sun Temple's general shape kept drawing her attention. "I noticed in my site survey that the same measurements kept popping up over and over again," she said in a release. "When I saw that the layout of the site's key features also involved many geometrical shapes, I decided to take a closer look."

What she found was twofold. First, it appears the Sun Temple was built using a common unit of measurement, which is roughly 30 cm. This in itself is a fascinating discovery, because we have no evidence that the Pueblo peoples had a written language or number system. In a recent paper for Journal of Archaeological Science Reports, Towers wrote that major structures at the site—namely, the retaining wall and four round, tower-like "Kivas"—were "laid out with remarkable precision, with the relative uncertainty on measurements estimated to be approximately one percent."

More incredibly, she also found that "key features of the site were apparently laid out using the Golden rectangle, squares, 45◦ triangles, Pythagorean 3:4:5 triangles, and equilateral triangles." She added that the "Sun Temple site thus likely represents the first evidence of advanced knowledge of several geometrical constructs in prehistoric America." Though ancient peoples in Greece also used the golden rectangle in their constructions, this would be the first evidence for a similar geometric structure in the pre-contact Americas. It means that the Pueblo peoples' urban layouts, which included cities carved into rockfaces and a sizable reservoir system, were aided by a sophisticated understanding of geometry.

Many archaeologists are leery of making such claims, because it's hard to know whether these shapes were intentional or not. Towers explained that she's leery of this, too, but she remains confident in her discovery:

Some individuals have pursued pseudo-scientific studies of geometric layouts of archaeological sites, and this unfortunately has led to a cachet of “woo science” associated with any study in this area... for instance, in various studies purporting evidence of geometric layouts associated with Southwest prehistoric sites (often associated with New Age theories), the author has noted that geometric shapes of arbitrary size are simply overlaid on a map of a site, without regard to whether or not the vertexes, sides, or size of the shape are meaningfully associated with any of the key features of the site... To ensure rigor in our analysis, we thus only examined potential geometries associated with either the size of key features like the four Kivas and the outer D, or geometries associated with measures between at least two of the key features. We also only presented results that can be independently verified by interested readers using aerial imagery available with software programs such as Google Earth, and we assessed the statistical significance of the apparent geometries we examined.

More study is needed to substantiate Towers' claim, but she's taken the first important step. She hopes that scientists can move on to study other ceremonial structures built by the Pueblo peoples, such as Chaco Canyon in New Mexico, which may have been built using the same standard unit of measure she discovered at the Sun Temple.

Journal of Archaeological Science Reports, 2017. DOI: 10.1016/j.jasrep.2017.01.009

Listing image by Sherry Towers