Dancing together: brains in sync
All human populations enjoy dancing in company. With or without music, dance is a multisensory experience that requires complex sensorimotor coordination. In addition, dancing in pairs or groups involves the coordination of movements between dancers to complement or synchronise with each other.
«When we are having a conversation, walking together, or simply sitting next to someone else, our postures and movements are coordinated»
Many animals synchronise their movements, from the sophisticated nuptial displays of great crested grebes (Podiceps cristatus) or the combat performance of Siamese fighting fish (Betta splendens), to the perfectly coordinated flights of thousands of starlings (Sturnus vulgaris) in a flock. Synchronisation is widespread among living organisms and has many different adaptive functions, such as anti-predator strategies (increased efficiency in surveillance, confusing the predator and reducing the probability of being chosen as prey) and others related to social cohesion.
Humans tend to synchronise movements spontaneously and unconsciously in different social contexts. When we are having a conversation, walking together, or simply sitting next to someone else, our postures and movements are coordinated. At first, there is a small delay, from seconds to tenths or thousandths of a second, as one of the participants imitates the movements of the other; but after a certain point, the movements can occur simultaneously (which implies anticipation). Synchronisation has been found to be faster and more precise the higher the affinity between two people (e.g., between friends or romantic partners), and, at the same time, such synchrony of movements favours the formation of bonds between strangers: people who synchronise their movements with ours (or vice versa) are more familiar and more relatable; they inspire more trust. Interestingly, synchronisation can also occur between individuals of different species; for example, dogs synchronise their movements with the humans they live with and show a preference for social interaction with people who synchronise with them. In our species, the ability to synchronise and the perception of asynchrony appear very early in development: months-old infants are able to synchronise their rocking with their mother’s and detect when there is a break in this synchronous interaction.
Not only are movements synchronised, but so are emotional states and certain physiological responses such as heart rate, breathing, and the release of certain hormones into the blood. Dancing in synchrony not only increases the perception of social bonding, but also raises the pain threshold through the release of endorphins. Recently, the development of hyperscanning techniques, which allow us to simultaneously record the brain activity of different people, has made it possible to investigate what happens in the brains of two people when they spontaneously synchronise their movements, and the answer is not surprising: the activity of the brains is synchronised. This brain synchrony could help us to understand each other’s intentions and share purposes and goals to facilitate cooperation. In fact, brain synchrony is greater when two people cooperate than when they make the same movements independently or in competition. In this context, dance may have evolved to increase group cohesion and facilitate cooperation, which favours brain synchrony between dancers.