Marcus Bockle

Studies of squirrel monkey show they have musical instincts.Marcus Bockle

Music skills evolved at least 30 million years ago in the common ancestor of humans and monkeys, according to a new study that could help explain why chimpanzees drum on tree roots and monkey calls sound like singing.

The study, published in the latest issue of Biology Letters, also suggests an answer to this chicken-and-egg question: Which came first, language or music? The answer appears to be music.

"Musical behaviors would constitute a first step towards phonological patterning, and therefore language," lead author Andrea Ravignani told Discovery News.

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For the study, Ravignani, a doctoral candidate at the University of Vienna's Department of Cognitive Biology, and his colleagues focused on an ability known as "dependency detection." This has to do with recognizing relationships between syllables, words and musical notes. For example, once we hear a certain pattern like Do-Re-Mi, we listen for it again. Hearing something like Do-Re-Fa sounds wrong because it violates the expected pattern.

Normally monkeys don't respond the same way, but this research grabbed their attention since it used sounds within their frequency ranges.

In the study, squirrel monkeys sat in a sound booth and listened to a set of three novel patterns. (The researchers fed the monkeys insects between playbacks, so the monkeys quickly got to like this activity.) Whenever a pattern changed, similar to our hearing Do-Re-Fa, the monkeys stared longer, as if to say, "Huh?"

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"This kind of experiment is usually done by presenting monkeys with human speech," co-author Ruth Sonnweber said. "Designing species-specific music-like stimuli may have helped the squirrel monkeys' perception."

The squirrel monkeys demonstrated that they understood sound patterns -- and when they changed. This ability, central to language and music, therefore evolved at least 30 million years ago in the small and furry tree-dwelling primate that was the last common ancestor of humans and monkeys. It's likely that all primates today share the skills.

Musical ability evolved in primates some 30 million years ago.iStockPhoto

The non-human primate world might be more musical than we tend to think. Squirrel monkey calls are so high pitched and musical sounding that, to an untrained ear, they sound like bird songs. Chimpanzees drum on tree roots in the wild.

"My colleagues and I built some primate drum devices, basically tough musical instruments specifically designed for chimpanzees: they are electronic, so can produce virtually any sound when played," Ravignani said.

He added, "We already pilot-tested these electronic drums in a group of chimpanzees, and the animals' enthusiasm in using them to produce sounds spurred us to continue on this line of research."

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Ravignani said they plan to collect sounds from chimpanzees and look for musical structures within.

Charles Snowdon, a professor of psychology and zoology at the University of Wisconsin-Madison, said the monkey study findings make sense.

"I think that the ability to produce and understand organized sound has been a trait of primates for a long time and, by this definition, many song birds can also be included, meaning that aspects of the origins of music can extend quite far back in evolution," Snowdon said.

Expect more studies with Dr. Doolittle-styled smarts, catering to what non-human species will likely be familiar with and understand.

As Snowdon said, "It is not surprising that musical ability and comprehension have an ancient history rather than evolving de novo in humans."