Why don’t dogs dance?

Hello Dear Reader,

For my regular readers I should update them with regards my family visit that I spoke about in my last blog. My brother and I had a wonderful time together during his trip to Switzerland. I did what all good big sisters should do and spoilt him as much as I could. In return he filled me with pride, hugs and laughter: pretty much a perfect little brother.

I say ‘little’ as he is 8 years younger than me – it is clear from the photo that he is not little at all! I remember when he fit into the crook of my arm…

…where does the time go?

Anyway, on to the wonderous world of music psychology. This week I have been reading a most enjoyable review article by Ani Patel. I am always keen to read Ani’s work, not only because we share an academic interest (music/language similarities) but also because I remember him as being a lovely person when I first met him years ago. This experience ties into the first entry from my quote page:

“I’ve learned that people will forget what you said, people will forget what you did, but people will never forget how you made them feel”  – Maya Angelou

When I was a young music psychology graduate student most academics were pleasant enough when I approached them with a question at a conference or during a visit . However, I find it impossible to forget two small groups of people: Those who were dismissive and rude, and those who were kind and generous with their time. Ani was in the second group. I always try to follow his example.

His latest review article is not on our shared research interest but one that nevertheless I find very engaging. The question of music and evolution. Even more intriguing is the title of the paper: “The Evolutionary Biology of Musical Rhythm: Was Darwin Wrong?”

The paper presents a quote from Darwin’s 1871 paper ‘The descent of man and selection in relation to sex’ where he states that :

“The perception, if not the enjoyment, of musical cadences and of rhythm is probably common to all animals, and no doubt depends on the common physiological nature of their nervous systems”

Darwin’s idea, according to Ani,  was that the key features of musical beat processing should be similar in humans and other species. And indeed we see many examples of animals who produce signals (calls, flashes) of a periodic nature or in synchrony with others. Incidentally, I wonder if fireflies really do this …or is that just in Disney?!

The problem is that the human ability to move to a beat, to entrain, appears to be very rare.  It is not as if we do it mechanically either, most people enjoy moving to music. Even if a person does not enjoy dancing they often smile as they tap their foot or bob their head to a good beat.

Why don’t other animals do this? As Tecumseh Fitch puts it ‘Why don’t dogs dance?’

Posibility 1) Darwin is wrong

Ani presents evidence that moving to a beat is rare amongst animals – the challenging evidence for a Darwinian view. Humans can easily and quickly pick up a beat from a simple rhythm produced by a metronome between 67 and 200 beats per minute. If Darwin was right then we would expect nonhuman primates to show a similar if more limited ability.

In the first study in this area, by Hugo Merchant’s lab, Rhesus monkeys took over a year of training to learn the basic metronome task. And even when they learned the task their movements were mostly a few milliseconds after the metronome beat. This indicates that they had learned to respond very quickly to a beat but not to anticipate it – which is what humans can do.

This monkey species appears to have little inclination or ability to move to a beat. An obvious question might be what about the great apes? They exhibit drumming-type behaviour in the wild.

The first study of synchronisation to a beat in 3 chimps has recently been published. Out of the three chimps only one synchronised to a beat. She only tapped to the beat in one out of three different tempi tested.

So far the evidence suggests that our closest animal cousins present a challenge to the Darwinian view that all animals can perceive and enjoy rhythm. However, the studies are small in number and sample size. To date I would not call them conclusive.

Possibility 2) Darwin is a little bit wrong

It is quite severe to claim that no animal other than humans can move to a beat. Indeed, the evidence suggests this is unlikely to be true.

Ani’s own hypothesis, presented first in 2006, was that the ability to move to the beat was driven by the evolution of complex vocal learning. This ability is rare in the animal world, being limited to humans, some bird species, elephants, whales, dolphins, and porpoises, some seals and bats. 

The vocal learning hypothesis has neural origins. The idea is that all the species above have tight neural couplings between auditory and pre-motor areas of the brain. This helps them mimic and learn complex vocalisations. It might also help them move to the beat.

Many of the animals listed above have been found to move to the beat, at least in transient bouts (much as a human child might). However, testing is ongoing with more species. The work to date does not definitely confirm (or refute) the vocal learning hypothesis. It will be important to test whether the animal forms of beat entrainment found to date represent genuine spontaneous movements.

Possibility 3) Darwin was right

The vocal learning hypothesis has one major advantage – it is testable. That means we are on the look out for non-vocal learners who can move to the beat. Only when we find them do we need to adjust the hypothesis to fit this data.

So far, one clear exception has challenged this prediction and in so doing, supports more the Darwinian view.

Ronan, a California sea lion. She learned to synchronize to a beat using head bobs and, crucially, her movements were flexible to varied tempi.  

Although this species is not a vocal learner, it must be noted that its close family do have this ability (true seals). We have to wait and see therefore whether this case really suggest that non-vocal animals can learn to move to the beat  – if they can learn in a way that works for them.

Conclusions

Where does all this leave us? A limited range of animals, including humans, can synchronise to a beat. At this point we have one good theory as to why this happens (vocal learning hypothesis) but no definite explanation as to why only this motley assortment of creatures show one of the key roots of musical ability.

We need to work out:

1) How many vocal learners can move to the beat – anyone fancy testing bats?

2) Are other tendencies necessary for human-like beat synchronisation, such as a propensity for social behaviour?

3) Are there non-vocal learners who can move to the beat? A primary candidate of interest is the horse – see this  video for an apparent example of a horse moving to a beat.

Answers to these and related questions aim to move us closer to understanding the evolution of human musicality. As Ani points out, even if Darwin is shown to be wrong in this case, his theory has provided inspiration for a field of study that is getting us closer to our musical roots.

Paper:  Patel, A.D. (2014) The Evolutionary Biology of Musical Rhythm: Was Darwin Wrong? PLoS Biol 12(3), e1001921