Ritual clues flow from prehistoric blood

Science News, Dec 23, 1989 by B. Bower

Ritual clues flow from prehistoric blood

Never mind conventional wisdom; you can get blood from a stone. Anthropologists have extracted the blood of humans, sheep and an extinct form of cattle from the surface of a stone slab at an approximately 10,000-year-old agricultural village in Turkey. Analysis of hemoglobin in the samples leaves them with intriguing clues and questions about the ritual activities of early farmers.

The polished slab lies among the remains of a structure known as the "skull building," which contains more than 90 human skulls and several complete and partial human skeletons.

"We don't know exactly what was going on in the skull building, but human and animal blood was abundant on the slab," says Andree R. Wood of the University of Chicago's Oriental Institute. "It reinforces an argument for at least its occasional use for the cutting up of humans as well as of animals."

Human sacrifice is one grisly possibility, Wood notes, or human bodies may have been carted to the building after death and placed on the slab for some type of preburial ritual. The skulls show no evidence of decapitation.

Whatever took place in the building, it now appears that one of the world's earliest known farming villages had developed surprisingly complex traditions by that time, she contends. Previous estimates place the emergence of such villages no farther back than 10,000 years.

Blood from the slab, dated with an advanced technique called accelerator mass spectroscopy radiocarbon dating (SN: 12/16/89, p. 388), is about 9,000 years old, say Wood and Thomas H. Loy of the Australian National University in Canberra. They describe the study in the winter JOURNAL OF FIELD ARCHAEOLOGY.

Their method for removing blood from stone was described by Loy in 1983 and has since been used in the laboratory with artifacts dating from as early as 100,000 years ago. But the new study, conducted at the village of Cayonu Tepesi, marks the first time researchers have removed, stored and undertaken preliminary analysis of blood in the field. This capability offers a great advantage when labs are far away and artifacts cannot be taken out of their country of origin, Wood and Loy maintain.

Loy's technique involves locating suspected blood residue with a low-power microscope, then analyzing it with a coated paper strip sensitive to hemoglobin. Confirmed blood deposits are scraped off and crystallized. The size and shape of hemoglobin crystals differ among animal species, allowing researchers to match a sample with a particular species.

Initial work at the slab identified human and sheep blood, as well as the blood of an unknown, nonhuman species. The team later obtained blood from bone fragments of an extinct cattle species unearthed at the site and found that its hemoglobin crystals matched those of the unknown species taken from the slab. This is the first identification of the blood of an extinct species, they say.

After analyzing the blood, the researchers excavated from the building a number of skulls and horns belonging to the extinct cattle. They also uncovered a large flint knife whose blade held traces of cattle and human blood. Wood says it may have been used in human sacrifices or mortuary rituals, but she notes that toolmakers' blood often ends up on sharp tools as a result of accidental cuts.

Ritual activity at Cayonu remains largely a mystery, says Robert J. Braidwood of the Oriental Institute. Nonetheless, he says, the cultural complexity hinted at by the skull building and other structures at the site strengthens his "gut feeling" that humans crossed the threshold to a village-farming life more than 10,000 years ago.