But what happens when you take away the cues that allow us to keep time, like the bass or drums in a song? Have you ever played a game of singing along to a song, turning the music all the way down, kept singing, and then turned the music back up, to see if your song matches the song that kept playing? Try it… a song with lyrics is easy because there are clues that allow us to follow the tempo of the song. However, if the interval without lyrics is long (10 seconds, for example), you will probably get out all out of sync.
Try another test: grab a stopwatch. Set it to count down to 10 seconds, and without looking, count those 10 seconds in your head. At the end, see if you managed to be precise and match the stopwatch. The results prove that an activity that seems simple is, in fact, nothing of the kind.
Several investigations have observed this phenomenon in the laboratory by carrying out conditioned behavioral experiments on birds, mammals and insects. For example, in exchange for certain stimuli, such as food, animals are capable of learning time intervals that last from a few seconds to several minutes.
Illustration: Gonzalo Nazati
Although this behavior has been widely studied under laboratory conditions, little is known about it in nature.
The neurobiologist Carlos Rodríguez, along with other colleagues, wanted to understand a little more about this phenomenon in natural conditions, so they studied the songs of a bird known as the Southern nightingale-wren (or scaly-breasted wren, Microcerculus marginatus). This small bird is found in the tropical forests of Central and South America. It intones a song with introductory notes sung quickly, followed by whistles separated from each other by silent intervals that increase in length. The first interval usually lasts less than 1 second, while the last one can last for more than 10 seconds. Analyses of this species’ songs show that the condition of not being able to keep time, present in other animals including Homo sapiens, does not apply to this bird; rather, the phenomenon that explains their song type is called “constant precision.” This means that this bird can calculate time intervals of up to 10 seconds with great precision, a precision comparable to a musician with 10 years of experience who counts in his or her head to keep the tempo of a song. Obviously, the bird is not capable of counting to be precise, in fact, the mechanism to achieve this type of song is unknown.
Two options of mechanisms that could regulate this phenomenon are proposed: a) it is a learned behavior or b) it is an innate behavior. In option a, the bird learns the song from other individuals; in option b, the behavior is not learned, but is genetically encoded.
However, these two options are not mutually exclusive since a song can have both a genetic component and a learned one, as has been observed in oscines or songbirds, a group to which the Scaled-breasted Wren belongs.
The oscines memorize a song produced by other individuals and, with practice, correct mistakes. Normally these errors are related to intonation. However, we can’t rule out that errors in tempo precision can be corrected. This mechanism could explain the variation in accuracy between songs; thus, birds with low accuracy could be young individuals with little practice. As in humans, musicians with more than 10 years of experience have greater precision.
On the other hand, if the mechanism were genetically encoded, then there would have to be specialized circuitry in the brain to produce the pattern of intervals. These specializations may take a long time to evolve, since not being able to keep time seems to be the default mode for animals, because it emerges from natural noise in neural circuits. The fact that the Southern nightingale-wren can keep time suggests the evolution of a mechanism that allows it to escape inaccuracies arising from neural noise.
With further research, it will no doubt be possible to determine the mechanisms which enable the Southern nightingale-wren to sing its particular song while keeping time like a seasoned musician.
And what is the use of this type of behavior for the bird? The tempo precision in the vocalizations can provide information about the reproductive or territory status of the animal that’s singing, generating an effect on sexual selection. In simpler terms, males with greater tempo precision will be preferred by femaless when selecting a mate.
This discovery, in turn, opens the door to further research and investigation. The most beautiful thing about science is that the possibilities for research are endless: the more we study, the more we realize how little we know. We now know that Southern nightingale-wrens sing by breaking the rules followed by many other animals. However, we know next to nothing about the mechanism that regulates this behavior and about other natural behaviors related to vocalizations.
The diversity present in nature goes beyond the number of species within ecosystems. Behind the number of species, there is an enormous diversity of behaviors, songs, evolutionary processes, etc.; many of them still unknown. The loss of biodiversity is associated with the loss of knowledge, and for this, and many other reasons, it is imperative we work on conservation of natural resources wherever they are located.
Photography: Andrés Cuervo
An innovative example of conservation is the Sacha Taki initiative, a project supported and promoted by leaders in the Ecuadorian field of conservation, together with the Sacha Warmi Foundation. The initiative’s aim is for UNESCO to declare the Mashpi Reserve and its surroundings, as well as some regions of Pastaza Province, as world heritage due to their ” acoustic value”, with a view to bolstering the protection of these areas. The criterion of “acoustic value” is not yet recognized by UNESCO anywhere in the world, so it would make a truly pioneering declaration. But what does the acoustic value of an area actually mean?
The different sounds of the forest, such as birdsong, frogs, insects, monkey calls, rain, wind, among others, merge in the trees to compose the most beautiful symphonies. For those of us who live in cities, listening to these concerts allows us to reconnect with nature, and recognize her majesty. For forest dwellers, such as indigenous peoples and other local communities, these sounds are an intrinsic part of their culture and daily lives; for example, the call of certain birds or frogs warn of an incoming rain shower, predict a good or a bad harvest, a good or a bad day, etc.
The bond between humans and their forest environments is so close that the possibility of losing the sounds of the forest is unthinkable. From that concern, the Sacha Taki initiative was born, aiming to highlight the beauty of these sounds, their relationship with culture and the importance of protecting them over time. By protecting the sounds of the forests, we guarantee the conservation of each one of the beings that make up these symphonies, from a small cricket that sings almost imperceptibly from a leaf, to a toucan that raucously announces its presence from the top of the trees, not forgetting the nightingale-wren which acts as the orchestra’s conductor, keeping infallible time.
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