C14 Dating the Collection

Contributed by Marla Taylor

You have probably heard of radio-carbon (C14) dating.  An invaluable tool for contextualizing the past, C14 dating is a method for determining the age of an object containing organic material by measuring stable and unstable (radioactive) isotopes of Carbon.  Developed by University of Chicago physical chemist Willard Libby in the 1940s, C14 dating was a game-changer for the field of archaeology. Libby received the Nobel Prize in Chemistry in 1960.

Instead of relying solely on relative dating – the basic concept that an object found below another is older than one found closer to the surface – archaeologists gained the ability to specifically identify a year range for organic artifacts.  The Peabody Institute was a contributor to this work through past curator, Frederick Johnson, but that is a story for another blog.

Lately, I have been working to facilitate C14 dating on bone artifacts from Pikimachay Cave in the Ayacucho Valley of Peru at the request of the 2019 Cordell Fellow, Juan Yataco.  Juan is revisiting work done in the Ayacucho Valley by Scotty MacNeish.  Back in the 1970s, MacNeish made some pretty bold assertions about the dates of human occupation in that region.  At the time, the C14 dates from animal bones supported his claims, but other archaeologists doubted whether those bones were associated with human occupation. 

While Juan’s specialty is stone tools, he also wanted to use improved technology to obtain an updated date for Pikimachay Cave.  Unfortunately, the first bone sent for testing failed to yield an appropriate collagen sample and could not be tested.  A second bone is on its way now.  Both bones were modified by humans and will provide a fascinating glimpse of the past.  Fingers are crossed for a better outcome this time around!