Traces of blood and fragments of muscle, tendon, skin and hair found on 2,000-year-old stone knives have given researchers the first conclusive evidence that the obsidian blades were used for human sacrifice.
     Researchers had long seen cut marks on ancient bones that appeared to suggest varied practices of dismembering victims in many pre-Hispanic cultures, but the find announced Wednesday positively identifies the sort of actual knives that were used.
     Researchers in Mexico had noticed what they believed were fossilised blood stains on stone knives as long as 20 years ago. But the institute said it took a methodical examination using a scanning electron microscope to positively identify the human tissues on 31 knives from the Cantona site in the central Mexico state of Puebla.
     The collection of stone knives is from the little-known Cantona culture, which flourished at about the same time as the mysterious city-state of Teotihuacan. Cantona preceded by more than 1,000 years the region's most famous human sacrifice practitioners, the Aztecs.
     The archaeologists who found the knives gave them to researcher Luisa Mainou at the anthropology institute's restoration laboratories about two years ago. With help from specialists at Mexico's National Autonomous University, they were studied under the scanning electronic microscope.
     While historical accounts from Aztec times, as well as drawings and paintings from earlier cultures, had long suggested that priests used knives and other instruments for non-life-threatening bloodletting rituals, the presence of the muscle and tendon traces indicates the cuts were deep and intended to sever portions of the victim's body. "These finds confirm that the knives were used for sacrifices," Mainou said.
     The find has already begun to shed some new light on the sacrifice practices of pre-Hispanic cultures, which believed that human blood was a sort of vital liquid needed to keep the cosmos in balance.
     Some knives in the test had more traces of red blood cells, while others had more skin, and others more muscle or collagen, "which suggest that each cutting tool was used for a different purpose, according to its form," Mainou said.

Edited from Daily Democrat, Associated Press (3 May 2012)