Researchers discover rewards of unselfish monkey business

Even monkeys know the value of a decent salary and profit sharing. <br><br>In the forest, capuchin monkeys in South America will trap their prey as a group, and allow one member to move in and make the

Tuesday, April 11th 2000, 12:00 am

By: News On 6

Even monkeys know the value of a decent salary and profit sharing.

In the forest, capuchin monkeys in South America will trap their prey as a group, and allow one member to move in and make the ambush. That monkey will then share the meat with its buddies.

Scientists from the Yerkes Regional Primate Center, part of Emory University in Atlanta, decided to see how strongly these primates are driven to share. The researchers set up an experiment in which one monkey couldn't pull a tray with apple slices within its reach without the help of another. In most cases, a second monkey would help the first get to the food, even though there was no guarantee of a reward in the end.

And in almost all cases, the first monkey offered apples to its helper. The scientists also discovered that when the second monkey was rewarded for its efforts, it was more willing to help share the work. In fact, a helper monkey was two to three times more willing to help pull the tray if it had just been rewarded for another pull.

The scientists also found that monkeys shared more of their food if they had help obtaining it. When monkeys got food on their own, they shared less of it with neighbors.

Capuchins and chimpanzees are the only primates that help one another hunt in the wild, the scientists say. Researchers believe that studies of these animals might offer insight into the evolution of cooperation among humans. The research appeared last week in the journal Nature.
-------

Comet Hyakutake's tail longest at more than 300 million miles

It sounds like a tall tale about a long tail, but astronomers say it's true: Comet Hyakutake has smashed the solar system record for tail length.

Two teams of astronomers report that in May 1996, Hyakutake's tail stretched more than 300 million miles through space. The previous record, held by the Great Comet of 1843, was about 200 million miles.

Both teams discovered the record by analyzing data from the Ulysses spacecraft, launched in 1990 to study the sun. Comet tails are formed by the solar wind, which drives particles surrounding a comet's nucleus into space. Thus a comet's tail always points away from the sun, regardless of the direction the comet is traveling.

Ulysses noticed unusual magnetic fields on May 1, 1996, astronomers from London reported in last week's issue of the journal Nature.In the same issue, astronomers from Maryland, Michigan, Switzerland and Germany reported that Ulysses detected particles typical of comet tails at the same time. Both groups noted that on that day, Ulysses was aligned with the sun and Hyakutake's location eight days earlier - about the time it should take for tail material to reach the spacecraft.

At the time, Hyakutake was hard to see from Earth; had its tail been fully visible, it would have extended nearly halfway across the sky, the London astronomers reported.
--------

Dental X-rays may reveal risk of some strokes, heart attacks

A dentist can detect the warning signs of cavities, gum disease and - perhaps - a stroke or heart attack.

Researchers last week reported evidence that panoramic dental X-rays - which encircle the jaw - might reveal whether carotid arteries are dangerously clogged. The carotids, found on each side of the neck, carry blood to the brain.

When they're blocked, people can have strokes; but people can have narrowed arteries without feeling sick. Evidence is growing, however, that dentists can see the buildup in the parts of arteries caught on a routine panoramic X-ray.

The latest research, presented last week in Washington, D.C., at a meeting of the International Association for Dental Research, was conducted on 818 Pima Indians in Arizona beginning in 1983. The tribe has a very high incidence of type 2 diabetes, which brings a high risk of cardiovascular disease.

Researchers from the University of Buffalo School of Dental Medicine reported that about 7.5 percent of the study group had clogged arteries visible on dental X-rays at the start of the study. By 1998, those with blockage were almost twice as likely to have died from heart attacks or strokes.