Radiation holds key to Inca riddle
By Mary Ann Albright, Corvallis Gazette-Times

Corvallis Gazette Times, OR
March 27 2005

An Oregon State University researcher is using modern technology to
unravel the mysteries of an ancient South American culture.

The Inca empire marked momentous state occasions with a ritual called
capacocha. These ceremonies linked the capital of Cuzco to remote
Inca provinces through the sacrifice of children and the burial of
precious objects.

OSU researcher Leah Minc used neutron activation analysis to identify
the compositional elements of 15th century pottery found in several
sacred burial sites. Establishing the artifacts’ makeup allowed her
to pinpoint their origins, and ultimately to better understand the
capacocha.

The findings were published in the March issue of the Journal of
Anthropological Archaeology and illustrate the possibilities of
archaeometry, a field that applies scientific analysis to
archaeology.

“This study gives us a whole different perspective on ancient
societies,” Minc said. “It was exciting to be able to shed light on
an ancient ritual in a way that no other technology would allow.”

Minc came to OSU last summer from the University of Michigan, where
she conducted these analyses. When the University of Michigan closed
its radiation center, Minc looked for a new institution with the
capabilities her research required.

The OSU Radiation Center “has a lovely reactor,” Minc noted. “All of
this requires the artifacts be placed in the neutron flux of a
nuclear reactor.”

Steve Reese, acting director of OSU’s Radiation Center, explained as
simply as he could how neutron radiation analysis works:

“You insert the sample into the reactor and bombard it with neutrons
that activate the sample. The elements in the sample absorb the
neutrons and become radioactive. You look at the radiation they emit,
and that tells what atoms are present.”

Minc looks at the types and quantities of trace elements in a sample
to determine its geographic origin based on its chemical
“fingerprint” or “signature.”

By applying this procedure to the Inca pottery, Minc determined that
both imperial and provincial people contributed to the burial gifts.
She compared samples from five sites, mostly in Peru and Argentina.

Contrasting the raw materials used to make the different ceramic
vessels allowed Minc to demonstrate that all of these sacrificial
burials were part of the capacocha ritual. The geographical scope of
the ceremony supports archaeologists’ belief that imperial Inca
leaders used the ritual to link the political heartland of Cuzco to
outlying provinces.

Minc spent several years on this project, but OSU’s resident
archaeometrist has plenty of other cultures she wants to study. One
current venture uses analysis of late Bronze Age Armenian pottery to
examine that society’s market system and trade routes.

Reese says Minc’s work will add to the radiation center’s prestige,
attracting more research grants and funding.

Prior to Minc arriving and beginning an archaeometry program, OSU
primarily used neutron activation analysis for geochemical analysis,
Reese explained. He believes Minc’s work opens up new possibilities
for the university’s radiation technology.