Scarlet Macaw Fossils Reveal When Complex Societies Formed in the American Southwest

The skull of a scarlet macaw (Ara macao) excavated from Pueblo Bonito in New Mexico in 1897. D. Finnin/ AMNH
Janet Fang 10 Jul 2015, 17:05

In the American Southwest a millennium ago, vividly colored scarlet macaws procured from the tropics hundreds of kilometers away were highly prized status symbols and cosmologically powerful agents. Researchers have now been able to radiocarbon date over a dozen fossilized scarlet macaws (Ara macao) discovered in New Mexico. Their findings, published in Proceedings of the National Academy of Sciences last month, suggest that social and political hierarchies emerged in ancient pre-Hispanic Pueblo settlements at least a century earlier than we thought. 

Beginning in 1896, archaeologists have uncovered interred human remains, symbolically important materials such as turquoise, and more than 400 scarlet macaw skeletons from numerous prehistoric settlements such as Chaco Canyon in northwestern New Mexico. Because scarlet macaws are native to Mesoamerica – which includes parts of Mexico, Central America, and South America – their presence here suggests the existence of long-distance trade networks characteristic of a complex society. According to previous attempts to date the macaws, they were obtained around 1040 to 1110 A.D. during a time of rapid expansion called the Chaco florescence. However, those dating methods were indirect, such as linking the birds to tree ring data or looking at the style of ceramic pottery associated with them. 

"In general, most researchers have argued that emergence of hierarchy, and of extensive trade networks that extended into Mexico, would coincide with what we see as other aspects of the Chaco florescence: roads being built outward from Chaco and the formation of what are called Chaco outliers that mimic the architecture seen in the cultural center," Stephen Plog from the University of Virginia says. Turns out, "sociopolitical hierarchies evolved over the course of nearly two centuries before taking the more visible forms seen in the Chaco florescence.”

The team used radiocarbon dating of bone collagen to directly determine the ages of 14 scarlet macaws excavated from Pueblo Bonito, one of the largest Chacoan great houses. The six oldest skeletons date back to between 885 and 990 A.D. and 12 of the macaws predated the Chaco florescence.

"Rather than the acquisition of macaws being a side effect of the rise of Chacoan society, there was a causal relationship," Adam Watson from the American Museum of Natural History says in a statement. "The ability to access these trade networks and the ritual power associated with macaws and their feathers may have been important to forming these hierarchies in the first place."

Exactly how the birds were acquired from so far away is still a mystery. "How likely was it that Southwestern people were going down into Mexico and bringing them back?" Penn State’s Douglas Kennett asks in a PSU statement. There’s no evidence that the birds were bred here, and based on the behavior of fledgling scarlet macaws, it’s unlikely that a human chain of supply spanned all the way from Mexico’s Oaxaca to Chaco. 


Modern view of Pueblo Bonito, the largest of the great houses in Chaco Canyon, which was occupied between about AD 900 and 1500. Pueblo Bonito had about 650 rooms. A. Watson/AMNH

Images: A. Watson/AMNH (top), Maciej Czekajewski/shutterstock.com (middle), A. Watson/AMNH

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