Polka Dot Architects

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When we humans meet another human, we often like to ask what that other human does. We often assume that what someone does is who they are, even if this isn’t necessarily true.

Still, in many cultures, what someone does comes to define how they are perceived.

Some new satellite images published this week show a strange and unexpectedly regular patterning of polka dot discs cut into vegetation, spread out across a large swathe of land near the Grand Canyon.

Patterned vegetation having a “polka-dot” arrangement (Courtesy Google Earth, coordinates: 36°17’16.79’’ N, 113° 05’ 57.66’’ W). Source: A.C. Sparavigna

Patterned vegetation having a “polka-dot” arrangement (Courtesy Google Earth, coordinates: 36°17’16.79’’ N, 113° 05’ 57.66’’ W).
Source: A.C. Sparavigna

At first glance, it looks like the land has a pale case of the measles. But a recently published paper points to a more likely reason: Each dot is an ant nest, and there are hundreds of them set neatly in a geometric arrangement.

The images put me in mind of this wonderful post over on the blog Ecology is not a dirty word, in which ecologist Manu Saunders discusses insects as they are described in an early entomology work, Insect Artizans and their Work (1919), by Edward Step.

Discs in patterned vegetation (Courtesy Google Earth, coordinates: 36°14’55.07’’ N, 113°05’05.22’’ W). Source: A.C. Sparavigna

Discs in patterned vegetation (Courtesy Google Earth, coordinates: 36°14’55.07’’ N, 113°05’05.22’’ W).
Source: A.C. Sparavigna

Saunders writes, “The book explains the insect world within a context of interest to contemporary society (economics and industry). Step chose this approach to awaken an interest in people for “whom a more systematic treatment would be considered dry and uninteresting”.

He uses the categories of artisanship or ‘industry’ (in the old-fashioned sense of craftsmanship) to group insect species.”

She continues, “Once upon a time, it was common to approach nature as functional, rather than delineated. ‘Ecosystem services’ is really just a new name for an old method. Everything in nature has a role. Before individual species were given names and separated into organisms, people recognised different animals, birds and plants through their seasonal activities. This tied in with mythologies and cultural beliefs, where every kind of plant, animal and ecosystem had a symbolism relative to human life. And so Step groups the insects he describes by the crafts they contribute to nature.”

The book’s table of contents brings us to Horticulturalists and the red harvester ant (Pogonomyrmex barbatus), the ant which is presumed to have made the polka dot arrays on the rim of the Grand Canyon.

As impressive as this large earth work is above ground, my guess is that the real artisanal work is going on below the surface.

The harvester ant, according to entomologist Dr. Walter R. Tschinkel, a leading figure in the study of ants and ant colonies, “collects seeds and stores them in underground chambers for future use, excavates a large, beautiful subterranean nest, decorates its nest disc with bits of charcoal and attracts many inquilines and myrmecophiles (Note: co-habiting organisims and animals that are associated with ants) that live in its nest.”

Dr. Tschinkel explores nests by making casts of them, and these casts are quite spectacular.

Some findings of interest – underground morphology varies among ant species, colonies may reach up to twelve feet in depth, and may hold up to 9,000 – 10,000 workers. Source: Tschinkel/DPages

Underground morphology varies among ant species, colonies may reach up to twelve feet in depth, and may hold up to 9,000 – 10,000 workers.
Source & caption: Tschinkel/DPages

These are works of intricacy, complexity and undeniable craftsmanship.

Ants are traditionally seen as hard workers (Edward Step himself asserts that one of the most quoted sections of the Bible is the injunction to consider the ways of the Ant), and being a hard worker is generally considered a virtue.

At the same time, we don’t actually like ants all that much. They bite, they infest all manner of human habitats, they can impact landscapes intended for grazing and harvest, and they are very difficult to eradicate. We appreciate their industry but not necessarily its products.

Yet if we judge humans by what they do, how hard they work and by what they create, how then are we to judge the large ant colonies that produce these structured arrays of architectural delights?

Close-up of a harvester ant colony cast. Source: Source: Tschinkel/DPages

Close-up of a harvester ant colony cast.
Source: Source: Tschinkel/DPages

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