The conclusion that at least one victim died by gunshot was supported by the discovery of iron particles around the edges of the half-inch wound and in the plug of bone that was knocked out centuries ago. The findings have not yet been published in a scientific journal but were presented in April at an archaeology conference and will be featured in a NOVA/National Geographic special on Tuesday.
Katherine Moore, a University of Pennsylvania anthropologist who is not a member of the research team but is familiar with its work, called the gunshot conclusion "very reasonable."
"The features on the hole match very, very closely with the features you would expect on a gunshot wound," Moore said. Firearms, she said, were part of the conquistadors' "package of violent tools for domination."
Team leader Guillermo Cock and colleague Melissa Scott Murphy, a bioarchaelogist at Bryn Mawr College, said their gunshot evidence was conclusive.
"There is no real question," Murphy said in a telephone interview from Peru.
To rule out a rock from a slingshot or some other projectile, the team turned to the Henry C. Lee Institute of Forensic Science, which is affiliated with the University of New Haven.
Analysis with a scanning electron microscope showed the bone plug was impregnated with iron particles, said Albert Harper, a forensic scientist and executive director of the institute. The iron concentration was five or six times higher than bone elsewhere in the skull, supporting the theory that it came from a musket ball and not from other sources such as the surrounding dirt in the cemetery, he said.
Researchers also found telltale iron particles in a cotton swab that they wiped around the edges of the wound, Harper said.
The firearm of the 16th century was a primitive killing machine compared with the efficient weapons used by today's armies or by gang members on the streets of Philadelphia.
Sometimes called an arquebus, its principal value came in shocking opponents, said Blair Turner, a history professor at Virginia Military Institute.
"They made a big bang and were kind of impressive," he said, "but were certainly not the mainline infantry weapon that anyone relied on, and they weren't very accurate."
Turner said he was not surprised to learn of the discovery of an apparent gunshot victim in Peru, which was conquered by Francisco Pizarro in 1532-1533. Written accounts indicate that Pizarro's countryman Hernán Cortés used firearms in his invasion of Mexico several years earlier.
The Peruvian skeleton and its 71 companions were found in the town of Puruchuco starting in 2004. More than 400 other skeletons were found in the same Inca cemetery, all of them buried in the traditional manner with ritual wrappings, the bodies in a crouched position, facing east.
But the 72 skeletons appeared to have been wrapped quickly in simple cloth and buried at a shallow depth, without customary funerary objects and facing in various directions.
"They were not properly oriented," said Cock, a Peruvian archaeologist who owns his own firm. "They were not properly wrapped. They were not properly anything."
Cock thinks the victims were members of a group that rose up against the Spanish invaders but were defeated in 1536 - a battle described by a 17th-century historian. The skeletons were found near a canal, in the approximate location of the battle.
Murphy is not sure the bodies are from that battle but says it is "certainly a possibility."
A graduate of Haverford College with a doctorate from Penn, her specialty is studying human remains in their cultural and historical context. She has been working in Peru on and off since 1999.
More on the Inca
Watch The Great Inca Rebellion, a NOVA/ National Geographic collaboration,
at 8 p.m. Tuesday on PBS.
View video from the archaeological site via
Contact staff writer Tom Avril
at 215-854-2430 or firstname.lastname@example.org.