Long before governments had the power to ping citizens on their smartphones, the pre-Hispanic inhabitants of New Mexico’s Chaco Canyon used conch shell trumpets to send out population-wide notifications. According to new research, the ancient Chacoans may even have deliberately designed their settlements to ensure that everyone was within earshot of a sea-snail toot at all times.

From around 850 to 1150 CE, the Chaco Canyon was the cultural heartland of the Puebloan peoples who inhabited the southwestern US. Typically, Chacoan centers from this period consisted of enormous sandstone structures known as "great houses", around which small clusters of domestic sites were scattered through the landscape.

Previously, archaeologists excavating the canyon have discovered conch shell trumpets within elite burials, despite the nearest source of such shells lying around 1,000 kilometers (620 miles) to the southwest on the Pacific coast. Providing an important if somewhat obvious insight, the authors of a new study explain that “these prized items would have provided their bearers, probably community leaders, with the means to create a very loud blast of sound.”

Trumpets of this kind continue to be used by the present-day descendants of these ancient Puebloans during ritual practices, all of which suggests that the shells may have played an important role in Chacoan life. To investigate, the study authors digitally modeled the reach of a conch trumpet blast when blown from the great houses of five different Chacoan settlements.

Their results demonstrate that the sphere of sound matches up perfectly with the distribution of domestic sites around each great house. It therefore appears that the ancient inhabitants of the Chaco Canyon deliberately arranged their villages so that the authorities could communicate with all residents at any given time simply by blowing on a sea shell.

“If leaders atop great houses needed to quickly communicate with all community residents, a conch-shell blast would have been a more effective method than relying on community residents to look in the right direction at the right time to see, for example, smoke/mirror signals,” write the authors.

Speculating on the function of these audible notifications, the researchers say that trumpets may have been used to signal the start of communal activities like religious ceremonies. “This is not unlike the idea of a medieval church bell calling a community to mass”, explained study author Professor Ruth Van Dyke in a statement via email.

More broadly, the researchers state that “the acoustic reach of a conch-shell trumpet could have been one way of ensuring the internal cohesion of Chacoan communities.”

The study is published in the journal Antiquity.