TUESDAY, Jan. 27 (HealthDay News) -- Babies who smile when they hear a Beatles classic may be more happy than gassy, suggest researchers who studied newborns and their capacity to detect rhythm.

"People can easily synchronize to music, because we have expectations about how the beat or tempo will proceed," said study author Henkjan Honing, a professor of music cognition at the University of Amsterdam. "We were very interested to see if we could show that newborns do this as well."

The researchers played rock music for newborn babies while monitoring their brain activity and found that even newborn infants were able to detect an off beat.

"Basically, we had these babies listening to a rock rhythm, which is very regular, and once in awhile, there is a missing downbeat," said Honing. "We can infer from this methodology that these babies have a high expectation of a beat on a moment which is completely silent."

The findings, which were expected to be published in this week's issue of the Proceedings of the National Academy of Sciences, add to a growing body of evidence about babies' understanding of the world around them.

"It's evidence for the fact that babies have a central rhythm when they are born," Honing explained. "It's pre-language, it's very musical and very rhythmic."

"There are studies that show infants can distinguish between their language and a foreign language in utero, and they are probably using rhythm to do that," said Ann Senghas, an assistant professor of psychology at Barnard College of Columbia University. "The downbeat is like an edge finder, or the boundary of rhythm."

But some researchers are cautious about extrapolating that humans are wired for music specifically, preferring to focus on the larger communicative benefits.

"You don't have to conclude that infants are specifically wired for music, but you can say that infants are naturally wired to find language in the world," explained Senghas. "We pick up on it by music, and we enjoy having it because of music, but I don't think we're wired for music."