Speaking in Tongues

It's been said of those ''American Idol'' contestants that they sing like birds, but in truth there's an important difference between human and avian vocal gymnastics. In people, the mouth, lips and tongue play an important role in shaping the sounds coming from the larynx. In birds, though, it has been thought that the upper vocal tract has little effect on what's emitted from the sound-producing organ (called the syrinx).

Researchers at Indiana University have now shown that in one parrot species, at least, the tongue can alter sounds in a humanlike way.

Scientists have long wondered whether parrots use their tongues to alter their vocalizations, both because the tongues are fleshy and mobile and because some species make complex, humanlike sounds. Previous experiments, though, used sounds produced by the parrot, so it was difficult to tell the tongue's effect.

''What we have added is a direct indication that the tongue can do these things,'' said Dr. Roderick A. Suthers, an Indiana professor and an author of a paper on the work in Current Biology.

The researchers got around the limitations of earlier studies by replacing the syrinx with a tiny speaker, to control the sound coming from the parrot. (This required euthanizing the birds, but they were working with monk parakeets, a pest species that is captured and euthanized in Florida.) Then, fitting the dead birds with a tongue-manipulation device developed by the lead researcher, Dr. Gabriel J.L. Beckers, they measured how precise tongue movements altered the sounds by changing the acoustics of the mouth.

The researchers identified four formants, patterns of frequency response linked to specific tongue positions. The human tongue creates formants, too; in American English speakers, for example, they are responsible for certain vowel sounds. So the finding that the bird's tongue has a similar effect, Dr. Suthers said, ''suggests that in this respect, production of parrot vocalizations and bird songs are more similar to human speech than previously thought.''

A Double-Edged Sword

In geopolitics, the domino effect -- the idea that one country's rise or fall may lead to the rise or fall of a neighbor -- has come in for its share of criticism. But in work on endangered species, a domino effect makes sense. If a certain plant becomes extinct, say, then an insect that relies on that plant to host its larvae may be in trouble.

New research by an international group of scientists shows the extent of the problem. The researchers, led by Lian Pin Koh of the National University of Singapore and Robert R. Dunn of Curtin University of Technology in Australia, designed a mathematical model and applied it to data on more than 12,000 plants and animals currently listed as endangered or threatened.

Their finding, published in the journal Science, is that an estimated 6,300 ''affiliate'' species are co-endangered -- meaning that if the species they rely upon dies out, they will too. In most cases, these affiliate species are insects, mites, fungi and other organisms that live or reproduce with the aid of the host species.

The researchers estimate that 200 species have already become extinct in this way. They suggest that this kind of co-extinction should be taken into consideration by those trying to conserve and manage endangered species.

Grizzlies on the Rebound

Whatever affiliate species live off the grizzly bear probably do not have too much to worry about these days. The bears, which have been listed as threatened or endangered in the United States for three decades, are rebounding nicely. In Yellowstone National Park and its surrounding region, they number more than 500, up from 200 in the 1980's.

The latest signs of recovery include a preliminary count this year of 48 females with cubs in the Yellowstone area, up by 10 from 2003 and more in line with the numbers from two years ago. The annual counts are conducted by scientists with the Interagency Grizzly Bear Study Team, a state-federal coalition.

For Stress, Try Face Time

A picture may be worth a thousand words, but the right picture may also be worth a relaxing massage or a yoga class. A new study has found that in sheep, at least, viewing a picture of another sheep's face can reduce stress.

Scientists from the Babraham Institute, a biomedical research center in Cambridge, England, isolated sheep for short periods, simulating the temporary penning that often takes place on a farm. This caused an increase in stress, as measured by heart rate, changes in movement and vocalization, and hormone levels in the blood.

''When we showed them face pictures of sheep, it reversed all of these symptoms,'' said Dr. Keith M. Kendrick of the institute's laboratory of cognitive and behavioral neuroscience and an author of a paper describing the study in The Proceedings of the Royal Society. Goat faces had less of an effect, he said, and an inverted triangle -- an abstract face shape -- had no effect at all.

Dr. Kendrick, who has been studying face recognition in sheep for about 15 years, discovered in earlier work that some sheep could identify at least 50 different sheep faces and 10 different human faces.

''Not only are they extremely good at identifying faces, they can also remember them for several years without having seen them,'' he said. So sheep are a useful model for trying to understand the highly developed face-recognition ability of humans.

The current study goes further, looking at the effect that face recognition has on other processes in the brain. It shows that seeing pictures of sheep ''shuts off activation of parts of the brain controlling stress and fear responses,'' Dr. Kendrick said.

In many human brain disorders, he added, this connection between recognition and response is missing. A schizophrenic, for example, may be able to identify people but cannot respond appropriately.

''We don't understand very well how the mechanism for identification and emotional response are linked,'' Dr. Kendrick said, so the work with sheep provides some clues.

The study also suggests a simple way for people to cope with the stress of isolation: keep a snapshot or two of a loved one around. ''It should be a fairly effective method for reducing separation anxiety in humans,'' Dr. Kendrick said.

That so many people keep family photos in their wallets or on their desks at work suggests it's a method that is already being used.

Drawing (Drawing by Felipe Galindo)