Samuel Belknap III, a University of Maine graduate research assistant working under the direction of Kristin Sobolik, found a 9,400-year-old skull fragment of a domestic dog during analysis of an intact human paleofecal sample. The fact that the bone was found in human waste provides the earliest proof that humans in the New World used domesticated dogs as food sources.
     "This discovery can tell us not only a lot about the genetic history of dogs but of the interactions between humans and dogs in the past," said Belknap. "Not only were they most likely companions as they are today, they served as protection, hunting assistants, and also as a food source."
     At the time Belknap found the bone, he was conducting his thesis research on ancient diet and nutrition of humans during the Holocene Era in the Lower Pecos Region of Texas. He discovered the bone, known as BE-20, during the 2009-2010 academic school year while examining a paleofecal sample recovered in the 1970s from Hinds Cave, a major archeological site in southwest Texas near the Mexico border.
     Belknap and fellow UMaine graduate student Robert Ingraham first visually identified the bone and Ingraham also found that the fragment closely matched that of a short-nosed Indian Dog from New Mexico. The bone was then sent to University of Oklahoma researcher Cecil Lewis, who runs the Molecular Anthropology Ancient DNA Laboratory, for DNA analysis. The analysis from the lab supported the conclusion that BE-20 is from a domestic dog rather than a wolf, coyote or fox, and is closely related to a species of Peruvian dog.
    The age of the bone and fecal material was confirmed by directly dating the sample using Accelerated Mass Spectrometric Radiocarbon Dating. Direct dating is crucial to the discovery, Belknap said. "For a long time there were several dog bones from Jaguar Cave in Idaho that were believed to be over 11,000 years old, but once they were directly dated they were found to be only 1,000 to 3000 years old," he said. "So it's a cautionary tale of the need to directly date things. It's important to do it." Although 9,400 years is considered ancient in the Americas, the remains of domesticated dogs in Europe have been identified to be well in excess of 10,000 years old.
    Belknap's find also provides the earliest direct evidence for dog as a source of food for human consumption. According to ethnographic studies, dogs were consumed either in times of desperation or times of celebration. Dogs were butchered in a specific way and may have been cooked in a stew, which could explain how bones from a skull and wrist or ankle ended up in the same paleofecal sample. "It could be that the smaller bones broke off in the butchering process and found their way into a stew or soup," Belknap said.

Edited from PhysOrg.com (11 January 2011)