In the future: A robotic Rover

Dogs may have a hard time wrapping their paws around this one: Robotic competition is nipping at their heels in the man's-best-friend department.

A study by Saint Louis University found that a lovable pooch named Sparky and a robotic dog, AIBO, were about equally effective at relieving the loneliness of nursing home residents and fostering attachments.

The study, in the March issue of the Journal of the American Medical Directors Association, builds on previous findings by the researchers that frequent dog visits decreased loneliness of nursing home residents.

Andrew Ng, who leads Stanford University's team in building a home-assistance robot and was not involved in the study, said the strength of the research is very encouraging. If humans can feel an emotional bond with robots, even fairly simple ones, some day they could "not just be our assistants, but also our companions," he said.

To test whether residents responded better to Sparky, a trained therapy dog, or the Sony-made robot dog, researchers divided 38 nursing home residents into three groups at a trio of long-term care facilities in St. Louis.

One group had weekly, 30-minute one-on-one visits with Sparky; another group had similar visits with AIBO; a control group did not visit with either dog. Their level of loneliness -- determined by residents' answers to several questions -- was tested at the beginning and near the end of eight weeks of visits.

Most of the elderly used Sparky, a 9-year-old, mutt, as a confidant, telling him "their life story," said Marian Banks, who adopted and trained Sparky after finding him behind her home seven years ago. "He listened attentively, wagged his tail, and allowed them to pet him," she said.

"AIBO is charismatic if you start to interact with him," said the study's author, Dr. William Banks, a professor of geriatric medicine at Saint Louis University. "He's an engaging sort of guy."

In the end, both groups were less lonely and more attached.

Sara Kiesler, professor of computer science and human-computer interaction at Carnegie Mellon University who was not involved in the study, said the problem is inferring it was the robotic dog and not the human who brought him into the room, she said.

Scientists have devised a way to determine roughly where a person has lived using a strand of hair, a technique that could help track the movements of criminal suspects or unidentified murder victims. The method relies on measuring how chemical variations in drinking water show up in the hair of people.

"You are what you eat and drink, and that is recorded in your hair," said Thure Cerling, a geologist at the University of Utah and lead author of the study published this week in the Proceedings of the National Academy of Sciences.

By measuring the proportion of heavier hydrogen and oxygen isotopes along a strand of hair, scientists can construct a geographic timeline. Each inch of hair corresponds to about two months, Cerling said.

His team accurately placed 200 hair samples in broad regions roughly corresponding to the movement of rain systems. "It's not good for pinpointing," he said. "It's good for eliminating a lot of possibilities."

Chicago archaeologists have solved the mystery of how the ancient Maya produced Maya Blue, a vivid and virtually indestructible pigment that was used for painting religious objects and human sacrifices to placate the rain god Chaak.

Researchers have known that Maya Blue results from a chemical bond between indigo dye and palygorskite, a clay mineral. But it was not clear how the Maya made it. The key was a three-footed pottery bowl that has been sitting in Chicago's Field Museum for 75 years.

Archaeologist Dean Arnold of the museum and his colleagues reported in the online edition of the journal Antiquity that substances in the bowl helped them conclude that Maya Blue was produced on site -- in Mexico's city of Chichen Itza -- during rituals by burning a mixture of copal incense, palygorskite and probably the leaves of the indigo plant.