Buildings at the Inca site of Tambo Viejo, on the south coast of what is now Peru, were constructed with a very special kind of sub-flooring — sacrificed guinea pigs.

The Inca empire was one of many around the world that carried out animal sacrifice to its gods. Excavations by Lidio Valdez at the Institute of Andean Studies in Berkeley, California, show that dozens of guinea pigs (Cavia porcellus) were ritually sacrificed there around 400 years ago. The victims were adorned with necklaces and earrings made of orange, red, purple and brown strings. Some were wrapped in cotton rugs. The animals were covered with a layer of clean river sand — and might have been alive when buried. Clay floors were then built over the sand.

The site is so dry that the little mammals were neatly mummified, the colors of their string adornment still bright today.

The findings help to confirm early Spanish accounts of the sacrifice of large numbers of guinea pigs by the Inca.