The close, personal bonds between humans and their dogs date back centuries in California, according to new archaeological research that illuminates the relationship between Central Valley Indian tribes and their dogs.

The evidence: Central Valley Indians buried their dogs carefully and with ceremony. People and their dogs were often buried together, curled up side by side.

Indian dogs were working animals. They defended the village by warning of intruders and helped procure food by chasing game during hunts.

They were also family pets, as shown by the respect with which they were buried, said Paul Langenwalter, a professor of archaeology and anthropology at Biola University in La Mirada. He has examined dog skeletons dating back to the 1700s.

"There are no pet cemetery areas, and we don't find the dog burials on campsites or any place where there aren't human burials," said Langenwalter, who specializes in human and dog relationships among California tribes. "They were buried with the people."

Langenwalter will present his research in Sacramento on Thursday at the annual meeting of the Society for American Archaeology. More than 3,000 experts from around the world are expected to attend the conference, which is open to the public.

His research contradicts older findings on the dog- Indian relationship. Renowned UC Berkeley anthropologist Alfred Kroeber, for example, concluded in 1941 that Indian dogs were "variously got rid of without formality."

Langenwalter's presentation will focus on recent research at burial sites in Calaveras and Merced counties that were home to the Miwok and Yokut, respectively.

The burial sites he studied, as well as others in California, show that Indians had a standard practice for burying their dogs: They were always buried in a "curled up" position as though sleeping, and the location was often marked by a rock cairn.

Langenwalter's research into historical accounts of Europeans' contact with California tribes also shed light on these relationships. Dogs, he said, were buried in the sleeping position as a way of transporting them to the spirit world.

"Some people had very warm relationships with their animals," Langenwalter said.

Debra Grimes, a Miwok Indian and cultural preservation specialist for the California Valley Miwok Tribe, agreed that Indians historically buried a dog with respect. "It is a family member to the tribal people," Grimes said.

She also agreed with Langenwalter about another common practice: When Indians died, their dog would be sacrificed and buried with them.

The practice is consistent with a larger pattern of property destruction when people died. Often their house and other belongings would be burned. The belief was that a person's property should join him in the spirit world.

But Grimes and Langenwalter disagree about how dogs were sacrificed.

Langenwalter said it was often done by crushing the dog's skull with a heavy object. He has unearthed many skulls with that kind of damage. Grimes said Indians fed the dog a poisonous plant.

Village chiefs or medicinal leaders often had their own dog, she said. These dogs didn't mix with other dogs in the tribe but spent all their time with their owner, and often were trained to find medicinal plants by smell.

Langenwalter said burial evidence indicates tribes kept both small and large dogs. Terrier-sized dogs were used to chase small game, such as squirrels and rabbits.

A larger type, generally about 4 inches taller at the shoulder, was used to chase and corner larger game, including deer. Many of these dogs showed a "significant number" of healed bone breaks, he said, possibly from being kicked by deer.

There was one circumstance in which dogs were eaten, Langenwalter said: to offer visitors food during ceremonies.

When visitors arrived, he said, the host tribe's pet or working dogs would be tied up in a hut or other shelter, and a second group of dogs would be let out into the village. Visitors would be allowed to kill and eat these dogs, and the dogs' owners would be compensated.

He speculates this was done so visitors would not use up the host tribe's food supply.

Grimes agreed that this occurred but said it was for different reasons. Dogs were offered primarily to women as a special "power" food, such as during marriage or birth ceremonies, she said.

"We don't have to use the canines like we did before," she said. "We're very thankful we can have them just as our pets and family now, and not have to utilize them as working dogs and not sacrifice them in a spiritual way."