So You Think You Can Dance? The Science of Rhythm. Even the dorkiest amongst us can tap a foot to a beat, or snap our fingers to music. Dancing is a uniquely human trait… or is it? Conspicuously, many of our animal friends (dogs and cats) or close relatives (nonhuman primates) do not show rhythmic entrainment to music , even after extensive exposure and training.
♫ Snowball, a cockatoo cutie, has millions of fans worldwide (I was sold on him after watching him dance to Queen’s Another One Bites the Dust: Snowball dances to Queen). Researchers changed the tempo (beats per minute, BPM) of his favorite song (Backstreet Boys, Everybody) and showed that he could slow down or speed up in response, although he does go out of synchrony occasionally.
♫ Budgerigars incorporate learned sounds in their warble songs. In a recent study, eight budgies were trained to peck a button (rather than move their bodies) in response to a metronome (instead of complex music). Budgies quickly got in the groove, doing better at faster tempos that matched their warbles. Like humans, they show auditory dominance, in contrast to monkeys that show clear preference for visual stimuli and required year-long training to learn to tap to auditory stimuli.
♫ In another study, researchers watched thousands of YouTube videos, or in science-speak, “an extensive comparative data set from a global video database systematically analyzed for evidence of entrainment in hundreds of species”. They concluded that only vocal mimics had the ability to entrain, that is, coordinate their movement rhythmically in response to sound. Vocal mimics include some species of birds (parrots, starlings, budgies), cetaceans(whales, dolphins), pinnipeds (seals) and even elephants.
♫ The conclusion is that rhythmic synchronization evolved as a by-product of selection for vocal learning. “Once auditory-motor coordination in the vocal control system has been established, a similar auditory-motor transformation system for other body parts might be derived from that”,says Yoshimasa Seki of the RIKEN Brain Science Institute.
♫ What are the implications of these findings? First, we now have additional models to study the neural and genetic basis of entrainment. Second, these examples of convergent evolution (when different species that are not closely related evolve the same trait) serve as statistically independent events, that allow us to test hypotheses about the evolution of human language,music and dance. Meanwhile, enjoy another overlap between Science and Art.
♫ Budgie study (check out the free supplemental videos): http://www.nature.com/srep/2011/111017/srep00120/full/srep00120.html
Snowball’s study: http://www.cell.com/current-biology/fulltext/S0960-9822%2809%2900890-2
For #ScienceSunday curated by Allison Sekuler and Robby Bowles .