J Some tunes stick in one’s memory,

sometimes with remarkable persistence. Think of “Happy Birthday,” “Old MacDon- ald,” and “Row, Row, Row Your Boat.” In laboratory experiments, even infants ex- hibit a keen memory for such songs.

A dozen of these childhood classics prove as memorable to rhesus monkeys as they do to people, a new study finds. This represents the first wellcontrolled demonstration that any nonhuman ani- mal perceives simple melodies, say psy- chologist Anthony A. Wright of the Uni- versity of Texas Medical School at Houston and his colleagues. Their report appears in the September JOURNAL OF Ex- PENMENTAL PSYCHOLOGY: GENERAL.

“The perception of melodies depends on the structure of our nervous systems, not just on childhood and cultural expe- riences,’’ Wright contends. “It’s any- body’s guess why this ability evolved in monkeys as well as humans.”

aEN(E of the week

Monkevs May Tune In to Basic Melodies

Even if monkeys hear no evil, they may appreciate simple tunes.

Wright’s group studied octave general- ization, a critical facet of melody percep tion. In Western musical scales, moving from one eight-note octave to the next highest octave represents a doubling of acoustic frequencies. If a melody’s other

Old Martian questions may have new answer A mystery surrounding the 1976 Viking

mission to Mars has lingered for a quar- tercentury, but a recent experiment may have revealed the solution. The new re- sults may guide future Mars missions, particularly those in search of life.

The Viking mission appeared to find that Martian soil can destroy organic molecules. Twenty-five years of trying to identify chemicals that might cause this breakdown hadn’t found a convincing ex- planation, says Albert S. Yen of NASA’s Jet Propulsion Laboratory in Pasadena, Calif. So, he and his colleagues simulated the Martian surface in their laboratory. They theorized that a chemical agent, su- peroxide radical ions, could arise and de- stroy organics on Mars.

In test-tube experiments, the resear- chers exposed mineral grains resembling those in Martian soil to a simulated Mart- ian atmosphere and then irradiated the samples with ultraviolet (W) light like that reaching Mars.

Using spectroscopy, Yen and his team observed that superoxide radicals form on the mineral surfaces under these conditions, they report in the Sept. 15 SCIENCE. Such radicals would survive at Martian temperatures, they add.

The researchers report that the super- oxide radicals are reactive enough to de- compose organic molecules at the Mar- tian surface. These radicals could also migrate through the Martian soil, the team claims. That is consistent with the Viking findings of soil capable of destroy- ing organic matter both at the surface and

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10 centimeters below, where superoxide- forming UV light wouldn’t penetrate.

Although the superoxides could ex- plain why Martian soil breaks down or- ganic molecules, there still are other po- tential culprits, comments Christopher P. McKay of NASA’s Ames Research Center in Mountain View, Calif. The most com- pelling aspect of the work by Yen’s group is its simplicity, he says, adding that he’d like t o know how far the superoxides could percolate through Mars’ surface. Such information would be useful for any missions that might search for superox- ides o r organic chemicals and other po- tential signs of life.

Yet Gilbert Levin, the leader of one of the other Viking experiments, insists that the fundamental idea that Mars’ surface lacks organics is wrong. He says that the technology used to detect organic mole- cules wasn’t sensitive enough. He holds that the results of his 1976 experiment were consistent with microbial life on Mars and says that the new report doesn’t adequately explain those results.

Others are skeptical of Levin’s inter- pretation of the Viking data. McKay says that Yen’s superoxide theory can ac- count for them more convincingly.

Superoxides would provide “a simple way” of destroying any organics that reach Mars’ surface in dust and meteorites, adds Allan H. Treiman of the Lunar and Plan- etary Institute in Houston. Like Yen, Treiman suspects that robots searching for Martian life will have to drill into rocks or dig deep into the soil. 4 Goman

SCIENCE NEWS, VOL. 158

acoustic properties, such as its pitch pat- terns and its key, stay the same, people easily recognize the tune when it shifts by one or more octaves.

Two earlier studies, one in 1943 with rats and one in 1988 with dolphins, also yielded evidence of octave generaliza- tion. However, those efforts lacked defini- tive experimental controls, Wright holds. Several other tests, including some with monkeys and songbirds, found no evi- dence for octave generalization.

The new study focused on a pair of adult rhesus monkeys that learned to re- port whether one sound matched anoth- er heard after a 1-second delay. Sounds included a boat whistle, owl hoots, and sonar pings. If the sounds were the same, a touch to a loudspeaker on the right yielded a food pellet: if the sounds dif- fered, a touch to a speaker on the left earned the prize.

Using this approach, both monkeys ac- curately identified repeats of any of 12 childhood songs-including those cited above-even when the melody shifted by one or two octaves. The monkeys suc- ceeded whether the tunes sounded as if they’d been played on a piano, guitar, o r other instruments.

The animals also displayed octave gen- eralization for new melodies, created ac- cording to a mathematical formula for tonal, well-structured tunes. Tonality refers to the relationship of a melody’s tones to a central tone, or key, that gives the passage a musical or songlike nature.

As previously reported for people’s musical skills, the animals’ ability to iden- tify childhood songs plummeted when they heard tunes that shifted by either one-half octave or 1 1/2 octaves. In these trials, the monkeys touched the speakers randomly. Similar problems arose when they heard octave shifts of single notes, random sets of notes, or atonal se- quences, in which there’s no key.

“Wright’s group makes a good case that these monkeys perceive whole tunes, not just isolated notes,” remarks psychologist Sandra Trehub of the Uni- versity of Toronto. Trehub, who studies infants’ musical perception, theorizes that many mammals are sensitive to ba- sic musical patterns.

Scientists have yet to reach a consen- sus on how to quantify the tonality of a sequence of musical notes, a concept that’s crucial in the new study, comments psychologist Diana Deutsch of the Univer- sity of California, San Diego. Although oc- tave generalization probably occurs in nonhuman animals, Deutsch says the new experiments don’t establish that monkeys perceive music. -B. Bower

SEPTEMBER 16,2000