Do dolphins have language?

I’m not a dolphin communication expert, but I have concerns with the recent paper by Vyacheslav Ryabov in the St. Petersburg Polytechnical University Journal: Physics and Mathematics.

It’s garnered a huge amount of extremely positive press coverage, but my takeaway from the paper is less enthusiastic: all we actually see is a 30 second snippet of captive dolphin sounds.

One of the simplest claims that the author makes is that the dolphins demonstrate turn-taking, and that this mirrors the nature of human conversations. Many researchers have developed ways to quantify turn-taking; it’s important to demonstrate that the apparent turn-taking is not just what would happen if two dolphins randomly produced sounds. Unfortunately, there is no such analysis in this paper. The author has only included one 30 second waveform and doesn’t provide any information about the total recording duration. They don’t prove that that particular snippet is representative of all of the recordings. Therefore, it’s impossible to determine whether they’ve cherry picked a 30 second recording that looks like it shows turn-taking out of what could possibly be hundreds of hours of recordings.

There are two sides to every conversation: perception and production. The author only looks at production in this study and doesn’t investigate whether the receiver dolphin was actually listening, or what they might have perceived/understood from the sender dolphin. One fundamental part of human language is categorical perception. We categorise every language sound we hear, even when the sounds actually occur on a sliding/continuous scale.For example, “ra” and “la” are actually continuous and you can make a sound that’s halfway in between them, but all native English speakers draw a line somewhere on that continuum to divide it into “ra” and “la”. I always hear it as being one or the other and never a combination. Some East Asian speakers don’t draw that line – they perceive that whole continuum as one phoneme (small chunk of sound) where I perceive that continuum as two phonemes.

The reason this is important is because the author states that “Each pulse … that is produced by dolphins is different from another by its appearance in the time domain and by the set of spectral components in the frequency domain. In this regard, we can assume that each pulse represents a phoneme or a word of the dolphin’s spoken language.” For one, the authors don’t show us the “spectral components in the frequency domain” at all. Most papers with data like this would include a plot that shows time plotted against frequency (how high or low a sound is), but this paper only shows time plotted against sound pressure level (effectively loudness). So we’re missing all the data we need to determine if the author’s statement is true.

But more importantly, they claim that each pulse represents a phoneme or a word because they’re all different. That’s unsurprising; every time I say a word, it’s going to be a very slightly different waveform. We just don’t know if the dolphins perceive the pulses to be different. In order to conclude that the pulses are equivalent to phonemes, the authors would need to show that the dolphins have categorical perception for these phonemes; that they categorise some of them as the same even though they’re slightly different. That would involve intensive behavioural work that was not conducted for this paper.

Another thing the author does is go through a list of characteristics of human language and attempt to demonstrate that dolphin communication also has those characteristics. All of these are difficult to demonstrate and the author has not conducted any experiments to explicitly address any of them. For example, one of these is duality of patterning, (i.e. meaningless phonemes make up meaningful words, and words make up messages). The author states that dolphin communication has this duality of patterning, but does not provide any evidence for this. Even in the earlier claim that the pulses equate to parts of human language, the author could not determine whether the pulses equate to meaningless phonemes or to meaningful words. There’s no evidence that the pulses are meaningless (very simple animal calls have meaning) or that the pulses build up into a meaningful message.

Ultimately, the paper really only showed one 30 second snippet where the dolphins did not produce sounds at the same time and with only two changes in “speaker”. It’s hard to draw much more of a conclusion from this study except that the author recorded dolphins for an unknown duration and found one short example of what superficially looks like a conversation.

Is My Immune System Normal?

Do three colds a year mean that my immune system is weak? When I went to the Cheltenham Science Festival, I saw an event called Is My Immune System Normal? One of the speakers was Prof. Arne Akbar of UCL, so I was asked to blog about the event for the UCL Events Blog. You can find out all about my immune system and how to determine if you’re as normal as me here.

Science festivals: For debating serious societal issues or just for fun?

Researchers, science journalists and comedians all come together at science festivals to inform and entertain the public with science. Sometimes there’s overlap with history (Lucy Worsley’s Fit to Rule) or books (James Gleick’s The Information), but often researchers simply sit on a panel and try to answer a question or come to a consensus on a particular topic (Is My Immune System Normal?).

At The Times Cheltenham Science Festival this past week, I saw comedy (Dara O Briain’s School of Hard Sums, Simon Watt’s The Ugly Animal Preservation Society), serious debate (Adam Rutherford discussing animal research, Science Minister David Willetts on science and the economy), and attempts to inform the public about all sorts of current science.

Attending science festivals is an expensive business. I was only able to make my way to Cheltenham for the week thanks to a UCL Graduate School bursary. It also takes time. The Cheltenham Science Festival runs from Tuesday mid-day through to Sunday night. It’s not most people’s initial idea of a fabulous holiday (though I managed to burn in the Cheltenham sun), so why do so many choose to attend?

Eric Jensen and Nicola Buckley have published a paper entitled Why people attend science festivals: interests, motivations and self-reported benefits of public engagement with research. They asked nearly 1000 Cambridge Science Festival attendees to answer a questionnaire about their experiences. They also followed up with some focus groups.

(Ironically, this paper about public engagement was published in a not-open-access journal called Public Understanding of Science. If you don’t belong to a university with access, expect to pay USD $25 to find out if people like science festivals.)

Crucial to the research is the distinction between first-, second- and third-order science engagement. First-order science engagement aims to spread science information and to invigorate public interest in science. Second-order engagement requires an active audience and involves creating a dialogue between scientists and the public. Third-order engagement gets very meta and aims to determine how science can serve society. During my time at Cheltenham, I saw first- and second-order engagement. Comedy fell squarely into first-order engagement, but the back-and-forth discussions between vegans and biomedical scientists about animal research were certainly second-order.

Calls for higher-order engagement from eminent societies have been made in the past decade, but are science festivals the right place for this? During my time in Cheltenham, I never paused and thought that I should be making “pluralistic stakeholder perspectives engaging in reflexive, critically-informed discussions and debates” (Jensen & Buckley, 2012, pg 3). No, I was far more likely to say “Dara O Briain was great fun this afternoon. I wish his interview with Peter Higgs tomorrow wasn’t sold out!”

Apparently I’m not the only person who feels this way. Jensen and Buckley found that their respondents were generally very happy with the bias towards first-order engagement at the Cambridge Science Festival. Attendees wanted to learn and to renew their excitement about science. Jensen and Buckley’s research suggests that the public doesn’t generally care about getting involved in philosophical debate at science festivals. In fact, one of the most common negative comments was that scientist panellists didn’t engage in enough conversation with each other. The attendees didn’t worry that their opinions weren’t being heard, but that the scientists weren’t hearing the opinions of other scientists.

The authors didn’t go so far as to draw conclusions about what science festivals should be, so I will. I think that we should relax about trying to philosophise about and during science festivals. They’re good fun and should continue to aim to enthuse young people to get and stay interested in science as well as to inform the general public about what we do. Let’s just have fun at festivals in the summer and continue to aim for second- and third-order engagement in other forums.

Dopamine and music: how enjoyment and movement are driven by the same chemical

Dopamine, one of the common neurotransmitters, underlies our ability to move, to learn, and to feel reward and euphoria. It accomplishes all of these roles by acting in four main pathways through the brain. For example, if dopamine transmission goes awry in the nigrostriatal pathway, Parkinson’s symptoms can occur. Alternately, dysregulation in the mesolimbic pathway can lead to gambling or drug addiction. This is because the mesolimbic pathway is involved in feelings of reward and pleasure.

Though neuroscientists are not sure what exact role dopamine plays in the reward system, we at least know that dopamine has an important role in regulating our sensations of euphoria. During enjoyable activities such as eating chocolate and having sex, an area of the brain called the ventral tegmental area releases dopamine into the reward pathway, which runs through parts of the brain responsible for emotion, such as the limbic system.

But while our desire for saturated fats and sex has obvious evolutionary benefits, cognitive musicologists do not understand why we experience intense pleasure when listening to music we enjoy. Linguist Steven Pinker has even referred to music as “auditory cheesecake” (Pinker, 1997). Though Pinker’s claim has been thoroughly criticised as being anti-music, recent research demonstrates how music does cause the same patterns of brain activation as that infamous cheesecake.

PET, a neuroimaging technique that shows brain activity, has been used to demonstrate that the mesolimbic pathway is active when we listen to music that gives us pleasure, though not when we listen to emotionally neutral music. Anne Blood and Robert Zatorre at McGill University enlisted the help of music students who commonly experience a “chill” or a “shiver down the spine” when they listen to certain pieces of music they enjoy. When the students experienced a chill in the PET scanner, Blood and Zatorre could see activity in the left nucleus accumbens and other areas that form part of the dopamine mesolimbic pathway.

However, seeing activation in a part of the brain associated with dopamine does not prove that dopamine is actually being released into one of its pathways. So Zatorre teamed up with “chill” expert Valorie Salimpoor to test if dopamine is released when participants experienced a chill. Participants listened to music that they enjoyed and were injected with a radioactive drug that binds to the same receptors as dopamine, called[11C]raclopride. The PET scanner measured the amount of [11C]raclopride that did not bind to receptors. This meant that if the brain released dopamine, the [11C]raclopride would not have as many receptors to bind to because the dopamine would be attached to those receptors already.

Zatorre and his colleagues found that dopamine was indeed released when the participants experienced a chill, primarily in the nucleus accumbens and other regions of the mesolimbic pathway. But they did not stop there. They also took fMRI scans of their participants, which allowed them to look at what parts of the brain were active on a more detailed timescale.

They found activity in the caudate, an area involved in regulating reinforcement of pleasurable stimuli, when the participants were anticipating the chill. At the actual time of the chill, however, activity moved to the nucleus accumbens. The team of neuroscientists believe their results show that dopamine is released in more than one area during a chill, and that leads to widespread effects throughout the brain, which explain why music has universal effects (Salimpoor et al., 2011).

However, it might not be that simple. Music preferences may be partially due to another function of dopamine: coordinating our ability to move. The nucleus accumbens, which is generally active when we enjoy something, also has links to other areas of the brain that neuroscientists know are involved in movement. One of the other four dopamine pathways is the nigrostriatal pathway, and it controls our ability to move. The nucleus accumbens projects to the substantia nigra, the “nigro” part of the nigrostriatal pathway. The interaction between the mesolimbic (reward) and the nigrostriatal (movement) pathways might be what makes us want to dance to music that we like (Koelsch, 2010).

This interaction has particularly important implications for Parkinson’s Disease patients. Parkinson’s occurs when the cells in the substantia nigra degrade. The lack of transmission in the nigrostriatal dopamine pathway leads to movement symptoms such as tremors and rigidity. Music therapists believe that music can ease the symptoms of Parkinson’s. One study found that motor responses and even emotional function improved when Parkinson’s patients participated in music therapy, by listening to relaxing music, playing instruments, and moving freely to music (Pacchetti et al., 2000). The rhythm of music seems to give Parkinson’s patients the ability to move and to control their movements. The researchers theorised that dopamine was released in both the nigrostriatal and the mesolimbic pathways, which allowed the patients both to move and to enjoy moving.

The effect that music has on dopamine release and transmission is still being studied by many neuroscientists, but it is becoming clear that music has an effect on the ancient and powerful reward circuits, as well as the pathways that allow us to move. Cognitive musicologist Henkjan Honing believes that comparing music to auditory cheesecake might not be as callous as it originally seemed (Honing, 2011). Music gives us chills and makes us dance; even with no convincing evolutionary explanation, we cannot ignore music’s power.