Many a parent may say that teenagers succumb to peer pressure. A study reports that toddlers and chimpanzees do too -- but orangutans don't seem to follow the crowd.

Daniel Haun, a psychologist at the Max Planck Institutes for Evolutionary Anthropology and Psycholinguistics, and his colleagues reported their findings in the journal Current Biology.

To conduct their study, they created a box with three colored holes. A treat appeared only when a ball was dropped into a particular hole. Toddlers, chimps and orangutans each watched as four members of their species who knew how the box worked interacted with it. The observers were then given a chance.

The toddlers and chimps tended to follow the behavior of the majority, while the orangutans seemed to choose a hole at random.

"One of the big differences is that chimps and humans continue to live in large social groups when they grow up," Haun said. "Orangutans don't."

For toddlers and chimps, the behavior is pretty reasonable, he said. However, when the toddlers and chimps saw just a single peer repeating a behavior, they did not copy it. This, too, makes sense, Haun said, "because it might be idiosyncratic to that individual." "If you see someone picking berries from a tree, you don't know if they're poisonous or not," he said.


There is no compelling evidence that poor dental health leads to clogged arteries, heart attack or stroke, and treating diseased gums will not reduce the risk of cardiovascular disorders, a medical panel said.

The panel's findings comprise the American Heart Association's new stance on the matter, altering a position many experts had accepted as gospel.

For decades, the accepted notion was that bacteria and inflammation associated with gum problems lead to dangers elsewhere.

But a team of cardiologists, dentists and infectious disease specialists assembled by the heart association reanalyzed more than 60 years of research -- 500-plus studies -- and found none produced a causative link between periodontal and cardiovascular disorders.

"Much of the literature is conflicting," said Dr. Peter Lockhart, the panel's co-chair, said: "If there was a strong causative link, we would likely know that by now."

Other experts said more research is needed. "What we have here is a very rigorous analysis," said Dr. Ronald Burakoff, chairman of dental medicine at Long Island Jewish Medical Center in New Hyde Park. "But it's possible that further research ... could explain the biological possibility of one causing the other."