Joint UCSC study provides insights into ancient Incan society

SANTA CRUZ — A recently published study, co-authored by UC Santa Cruz Anthropology Professor Lars Fehren-Schmitz, analyzing the 500 year-old DNA of those buried near Peru’s iconic Incan citadel Machu Picchu, shows that the servant class that lived and died there — forcefully relocated to the structure by the Incan empire — hailed from more diverse backgrounds than scientists had anticipated.

“The people that we are actually looking at are servants to the royal family,” said Fehren-Schmitz. “The Inca had a very complex system of forced relocation that they also used to control the places that they occupied and to maintain their political relationships.”

The recently published study, titled “Insights into the genetic histories and lifeways of Machu Picchu’s occupants,” was conducted over a 12-year span, and included researchers from Yale, Universidad Nacional de San Antonio Abad del Cusco, Tulane University, the Max Planck Institute for Evolutionary Anthropology, in addition to UCSC and was made possible through an agreement between Yale, the State of Peru, and the University of Cusco to return artifacts and human remains from the Hiram Bingham Expedition collection back to Peru.

Fehren-Schmitz, whose expertise lies in archeology and genetics, and is also the associate director of the UCSC Genomics Institute, has been working on the Machu Picchu study from the beginning. More than a decade ago, while finishing up his doctorate in his home nation of Germany, he attended a conference in Lima, Peru, where he met Yale Anthropology Professor Richard Burger, who inspired the idea of the study and is also a co-author.

“At that time, Yale was involved in negotiations with the State of Peru to return all the artifacts and human remains from the Hiram Bingham excavations in Peru,” said Fehren-Schmitz. “He offered me to come over as a postdoc to help with the human remains of the repatriation to Peru.

Burger then suggested that Fehren-Schmitz attempt to analyze the DNA of the recovered human remains, which were taken from Machu Picchu in the early 20th century. In the early 2010s, Fehren-Schmitz finished up his studies at Yale and began working as a professor at UCSC in 2013.

“Before that, I’d never even thought about the possibility of having access to the human remains buried at that site,” said Fehren Schmitz. “That started the whole project. It took about 12 years to finish it for many reasons.”

Fehren-Schmitz found that the DNA extracted from the teeth of the 34 approximately 500-year-old cadavers was in bad shape, and the technology didn’t yet exist a decade ago to analyze it. Over time, he and other researchers developed the technology and methods necessary to make sense of the damaged genetic material.

“It took quite a lot of R&D work here, developing our methods, and enhancing our success rates to isolate and to sequence the genomes of the individuals that we just published,” said Fehren Schmitz. “Twelve years ago, it wouldn’t have been possible to do what we’ve done now.”

According to Fehren-Schmitz, the current understanding among scholars is that Machu Picchu served as a seasonal mountain getaway for Incan emperors beginning with the emperor Pachacuti and was in use from about 1420 to 1530.

Although, none of the individuals buried in the caves around Machu Picchu were of the Incan royal line, who were entombed at the Incan capital of Cusco, but were skilled craftspeople and high-ranking officials from peoples conquered by the Incas.

According to Fehren-Schmitz, the Incans would sometimes force these conquered peoples to relocate away from their homelands to places such as Machu Picchu where they would work as servants, or yanacona, but that didn’t mean they were forced to do hard labor. The yanacona served as religious advisers and specialized workers.

“It was definitely not a city in the traditional sense,” said Fehren-Schmitz. “There was a continuous population living at the site and these are the individuals that our study focuses on. They probably didn’t occupy many of these fascinating buildings there, but served the site and kept it alive while the royal family was there and while they were not there.”

Because of previous studies about grave goods, and the understanding that yanacona came from a wide area around the Andes Mountains, Fehren-Schmitz expected lots of genetic diversity in the 34 individuals whose DNA was analyzed, but he was surprised to discover that the population had a high level of genetic diversity from the mountain retreat’s founding to its end, which didn’t seem to match up with the chronology of Incan conquest.

“We actually find people with ancestry from faraway places right at the beginning of the site,” said Fehren Schmitz. “We cannot say that means that the Incan empire expanded much earlier than we thought, or that it simply means that the Incans had interactions with the people in these regions, where people were taken for political leverage, before the Incas occupied these territories.”

After more than a decade of work on the study, and with the cooperation from a broad range of academic colleagues, Fehren Schmitz said he is pleased that the results are published and available to the world at-large.

“You can’t do a study like this with just one individual,” Fehren Schmitz. “You need all the expertise to create the most complete picture that you can. Studies like this should always be an interdisciplinary effort and this one was a good example of that.”

With the methods to collect, analyze and contextualize the genetic information of long-dead humans now honed, Fehren-Schmitz said he is eager to expand the analysis to other regions, which he hopes will provide insight into the genetic effects of European colonization on the indigenous peoples of South America, especially around the Andes.

“This is where my heart is,” said Fehren-Schmitz. “The Andes are gigantic and there’s so much to do still, and now with all these methods and frameworks we’ve developed in this 12-year project, we can move much faster.”

To read the study, visit science.org.