Thinned Ozone Leaks UV Rays

Since scientists first discovered that Earth's protective ozone layer was thinning, researchers have been predicting that increased levels of dangerous ultraviolet (UV) radiation would penetrate the atmosphere. Now, scientists have found the strongest evidence yet that this has begun, at least in New Zealand.

Richard McKenzie, of New Zealand's National Institute of Water and Atmospheric Research, and colleagues studied UV levels over a decade and found that the amount of UV radiation reaching the ground increased by 12 percent by the summer of 1998-99, the researchers report in this month's issue of Science.

Increased UV levels could have a variety of adverse effects, including increasing rates of skin cancer and cataracts and possibly damaging the environment by killing sensitive forms of life, such as algae. The ozone layer is expected to begin to thicken again because of the phaseout of ozone-destroying chemicals. But how soon remains unclear.

"Although the stratospheric loading of ozone-depleting substances is now close to the maximum expected . . . there is concern about possible interactions between ozone depletion and global warming, which could delay the recovery of ozone by decades," the researchers write.

Male Bonding Among Peacocks

Birds of a feather flock together. But why do male peacocks strut their stuff near other males that repeatedly beat them out in their quest to find a mate?

The answer, perhaps, lies in brotherly love. Male peacocks may figure that if they are not going to win the mating game and pass on their own genes to the next generation then the next best thing may be to help their close relative pass on their genes.

Marion Petrie, of the University of Newcastle in Newcastle-upon-Tyne in England, and colleagues conducted DNA fingerprinting on male peacocks that congregated in the Whipsnade Park north of London and found that those that gathered together tended to be closely related. When the researchers released groups of unrelated and related birds, the animals tended to congregate with their relatives.

"It may be that the inclusive fitness benefits of cooperating with relatives to attract mates outweigh any costs of communal display," the researchers write in the Sept. 10 issue of Science.

Human Creativity vs. Computers

Humans like to think they are unique in many ways, including their ability to be creative. But can computers be as creative as people?

Researchers at the Hebrew University of Jerusalem devised a relatively simple computer program to create advertising ideas. They then presented the results to a panel of judges who compared these ideas with ads by advertising executives and laymen.

"The human lay subjects given complete freedom to create failed to reach even the low threshold of creativity determined by the simple computer routine," the researchers write in the Sept. 3 issue of Science.

The findings suggest that "we should encourage creativity in new ways," the researchers write. "Randomness is still clearly of value: Several of the greatest inventions in history occurred randomly, as non-replicable creative sparks." However, "most creativity tasks cannot be accomplished by a random search, and the search might be harmful at worst, or inefficient at best."

Hippos as Whales' Missing Link

Scientists have long believed that whales descended from mammals that lived on land, but it's been unclear which animals. Now, researchers have produced new evidence that the closest living relative to whales are hippos.

Norhiro Okada, of the Tokyo Institute of Technology, and co-workers analyzed the genes of whales, hippos and other animals and found that the whales are more closely related to hippos than they are to such mammals as camels, pigs, giraffes, sheeps and cows.

The findings are consistent with those of previous research that suggested whales are more closely related to hippos than to pigs, which were once thought to be whales' closest living relatives. They also suggest, the researchers say, that studying genes might be a better way to determine which animals are closely related than pursuing the traditional method of looking for similarities in their physical features.

A Laughing Matter of Muscle

Many people literally become weak in the knees when they laugh. Now, researchers think they know why.

G.J. Lammers, of the Leiden University Medical Center in the Netherlands, and colleagues showed four healthly volunteers slides depicting various emotions, including several that were humorous, and measured their "H-reflex," which activates the soleus muscle in the calf.

"The H-reflex virtually disappeared in all four people when they laughed out loud, whereas it decreased much less when they did not," the researchers write in the Sept. 4 issue of the Lancet. The researchers then repeated the experiment with three people who they made laugh by telling them jokes.

"We postulate that the decrease in H-reflex amplitude during laughter is the neurophysiological equivalent of the common feeling of being 'weak with laughter,' " the researchers write.

The researchers speculated that the findings could help explain "cataplexy," which is a sudden loss of muscle tone that occurs among some people and is "triggered by strong emotions and typically occurs during laughter."