Do birds have their own language?

In the chirping, echoing sounds of birdsong, scientists have found some similarities with human language.

In our quest to find what makes humans unique, we often compare ourselves to our closest relative: the great ape. But when it comes to humanity's quintessential language ability, scientists find even more interesting clues.

Human language is made up of an impressive innate ability to pronounce. Newborns can hear sounds and words, form memories of them, then try to make these sounds and improve as they get older. Although primates (regardless of humans) can learn to use their innate voices in new ways, they have not shown the same ability when learning new calls. Interestingly, in a small number of mammal species not closely related to us, including pigs and bats have this ability. Among the 'acoustic learners' that do not count humans, scattered around the world, the most impressive are birds.

A bird perched on a pole in Suffolk, England, singing. (Photo: Avalon/Universal)

Parrots, songbirds, hummingbirds can all learn new pronunciations. The calls and songs of some species in this group seem to have more in common with human languages, such as directional communication and the use of simple forms in some elements. human language such as phonology, semantics, and syntax. There are also more obvious similarities, such as similarity in brain structure, that cannot be found in species that do not have the ability to learn pronunciation.

These similarities have fueled a research boom in recent decades, says Columbia University researcher Julia Hyland Bruno, who specializes in analyzing the social dimensions of zebra sparrows' songs. 'A lot of people have likened the similarities between language and birdsong,' she said.

Hyland Bruno studies zebra finches because they are more social than most other migratory birds - they prefer to travel in small groups from which to congregate in larger groups. 'I was intrigued by the way they learned the culture of sound transmission in their groups,' Hyland Bruno said.

Both bird song and human language are passed down culturally to future generations through learning pronunciation. Populations in the same bird species that are geographically far apart can produce small changes in song over time, eventually leading to a new 'dialect' – a process similar to how birds who develop distinct accents, dialects and languages.

With all these similarities, a reasonable question is whether birds have languages ​​of their own. This depends on how you define the language.

Many birds use different alarms depending on the predator.

'I wouldn't say they have language the way linguists define it,' says neuroscientist Erich Jarvis of Rockefeller University in New York City. But for scientists like Jarvis, who studies the neurobiology of acoustic communication in birds, he says: 'I would say they have a remnant or an embryonic form of what we have. can be called spoken language'.

'It's like the word 'love'. You question what love is to many people, and will receive countless different definitions. That means it's part of the mystery'.

According to Jarvis, there are many factors in spoken language, and some are more concentrated in particular species than others. A fairly common element is auditory learning, like a dog responding to a 'sit' command. The learning of speech by humans and some birds is one of the most distinctive, but these are shared only to some extent with other animals, he said.

The grammar of birds sounds similar to humans

An important element in human language is semantics, the connection of words with their meanings. Scientists have long assumed that unlike our words, animal calls are involuntary, reflecting the animal's emotional state without conveying any other information. But over the past four decades, numerous studies have shown that different animals have distinct calls with specific meanings.

Many birds use different alarms depending on the predator. The Japanese sparrow, which nests in tree holes, has one call that causes the chicks to crouch to avoid being pulled out of the nest by crows, and another to alert the chicks to jump out of the nest when caught by a tree snake. attack. Siberian jays adjust their calls depending on whether they see a perched hawk, search for prey or actively attack – and each call elicits a different response to the jays. near. Meanwhile, black-hatted tits will vary the number of characteristic 'dees' sounds in their calls to indicate relative size and predator threat.

Siberian jay. Photo: Garth Peacock.

Two recent studies show that the pronunciation order of certain birds can affect their meaning. Although this idea is controversial, it probably represents a rudimentary form of rules governing the order and combination of words and elements in human language known as syntax. , illustrated by the classic example 'dog bites man' with 'man bites dog'.

In addition to warning sounds, many birds use recruitment calls to summon other members of their species. Both the Japanese sparrow and the southern ibis seem to combine warning calls and summons to create an appeal to 'arm up', gathering companions in crowds to harass and repel predators. . When the birds hear this sound, they will approach the source of the sound while scanning their surroundings for danger.

Scientists led by Kyoto University researcher Toshitaka Suzuki have found that the order of combinations of calls is important for the Japanese corn finch. When Suzuki's team played the recorded 'alarm + summon' sequence sound to the wild sparrows, it produced a much stronger vibrational response than the 'summon + alarm' order. motion' is reversed. This could simply be explained by the fact that the birds responded to the 'alarm + summon' combination sound as if it were a signal of their own without ever delineating the components of the combination.

Another family of finches, the willow tit, also have their own unique sound, which Japanese finches still understand and respond to instinctively. When Suzuki's team combined the 'summon' call of the willow sparrow with the 'warning' of the Japanese sparrow, the Japanese sparrows responded with the same type of behavior of scouting and approaching, but just when the components are in the correct 'alert + summon' order.

'These results demonstrate a new similarity between animal communication systems and human language,' Suzuki and colleagues wrote in the journal Current Biology in 2017.

But the question is whether interpreting the combination of finches and babblers really fits into human language, which involves more complex sequences, says executive neuroscientist. en Adam Fishbein of the University of California, San Diego said.

'If birds are doing something like language, the result will be a bunch of different combinations of things. This is still a system that is limited to them,' Fishbein said.

Understanding is limited by what people hear

Fishbein's own study of zebra finches' songs suggests that syntax may not be as important to birds as it is to humans. 'I have a feeling people are trying to impose their way of thinking about communication on what birds are doing,' he said.

Bird songs can be very complex, tending to the typical sequence and pattern of notes, syllables, and motifs. So their songs may be more closely related to human language than their signaling and collective calls. To the human ear, each part of a bird song is easily associated with the syllables of a word, so it is easy to assume that the order of each part is important in terms of the message. Perhaps surprisingly, however, we know so little about how birds' ears perceive the sequences of their songs. Fishbein's research shows that what birds hear from singing can be very different from what humans hear.

Fishbein studied zebra finches, which were trained to press a button when they noticed a change in the sound they heard. When the birds correctly identify a change, they receive a reward of food. If the guess is wrong, the lights in the fence surrounding them will go out immediately. Fishbein examined the differences that birds can actually decipher, helping scientists understand which aspects of song are important to them.

In an experiment, Fishbein and his colleagues played back and forth the standard sparrow song at regular intervals before switching to a different version with their rearranged syllables. Humans can easily hear these changes, but the birds are very bad at determining the sequence of disturbances.

The birds performed much better in another test that Fishbein performed. Within each syllable there are higher frequency details known as 'temporal fine structures' like what humans perceive as timbre or tone. When the scientists interfered with the delicate structure of the song by playing back one of the syllables, the birds 'catched' them exceptionally well.

Fishbein said: 'It's an aspect of sound where they hear a lot better than we do. So they can exploit sound levels that we wouldn't be able to exploit if we just happened to hear birdsong."

Linguist Juan Uriagereka, who has worked with Fishbein at the University of Maryland, says our understanding of what birds hear and what influences them has been limited by what we hear. , the same is true of many scientific studies, statistical analyzes used to analyze bird songs. 'Ten years ago, we didn't even know what units they combined. And of course, what we think is that unit is just our guess, right?', he said.

Japanese corn sparrow.

Although all male zebra finches learn the same unique song, the scientists have found that there is a difference in the temporal structure between standard song representations, suggesting that the species This bird has a much richer communication system than we suspected. 'It is possible that much of the content is encapsulated in individual elements, and how they are arranged has no bearing on the conveyance of meaning,' says Fishbein.

Purposeful communication

Even if some birds show rudimentary aspects of human language, we still know very little about what is really going on in their minds. Most research on animal communication has focused on describing signals and behaviors that may, on the surface, be very similar to human behavior. Determining whether underlying cognitive processes drive behavior is therefore equally difficult.

The focus that people need to understand here is the element of intent. Are animals merely responding to their environment or are they actually trying to communicate with each other? For example, when it detects food, a bird may make a distinctive call to attract its fellows. Would that be 'Hey! Food!' - unintentionally attracting other birds? Or something like: 'Hey guys, come see this loot I found?'.

Signs of intent have been shown in many animals. Ground squirrels, Siamese fighting fish, chickens and even fruit flies change their signals depending on which receptives are around, an indication that they have some active control over the signals emitted . Other animals seem to intentionally 'show' something, such as a dog looking back and forth between humans and a hidden bag of snacks or toys, perhaps even adding a barking to get people's attention first. Crows also seem to show objects to other crows by holding them in their beaks - usually only when the other crows notice.

Some of the most recent examples of intentional bird communication have come from observations of wild Arabian babblers at the Shezaf Nature Reserve in Israel. A team led by researcher Yitzchak Ben-Mocha captured adult babblers coaxing their young to move to a new shelter. The adults will chirp and flap their wings before the young and then move towards the shelter. If a juvenile doesn't immediately obey or stops in the way, the adult will turn around, singing and dancing over and over again until the young do.

Scientists call such signals intentional communication. Some researchers suggest that this is a precursor to second-order intentional communication. This involves the sender knowing something about the mind of the receiver, such as a bird finding food that knows its fellow has not yet recognized the existence of that food and is trying. Notice to that silly bird. And as you might have guessed, this kind of mental allocation is a difficult behavior to test.

Scientists are taking a different approach to trying to understand what underlies such communication by comparing brain structures that enable vocal learning in songbirds and humans.

The mechanism by which birds make sounds is very similar to humans

Although humans and birds are very distantly related - their last common ancestor existed more than 300 million years ago - the two have very similar brain neural circuits for learning pronunciation. . Non-human primates, our closest relatives, lack specialized brain circuits to mimic sounds, leading scientists to conclude that this ability did not come from a common ancestor. This ability must have evolved independently in birds - an example of what is known as evolutionary convergence.

'It's been assumed that species that are more closely related to us will be most like us. And that's true for many but not all features,' says Rockefeller's Jarvis.

Jarvis studies the evolution of language by looking at the brains of songbirds. Innate sound-producing animals control the muscles that make those sounds through a circuit in the brain stem, an area near the spinal cord that regulates automatic functions like breathing and heart rate. "What has happened is that humans and songbirds have developed circuits in this new forebrain to produce learned sounds, which help control brainstem circuits for innate sounds," says Jarvis. born'.

His theory explains how similar neural circuits for vocal learning develop many times in distantly related species, they are built from an adjacent circuit that controls the learning of certain movements. 'The speech-language brain circuits in humans and the singing neural circuits in birds were developed by complete duplication of the surrounding motor pathways,' Jarvis argues.

According to Jarvis, how the entire brain circuit is copied remains unclear, but it is possible that it is similar to how genes are sometimes copied and then used for other purposes. However they have evolved, songbirds and humans have rare similar brain circuits that allow them to learn and imitate sounds. This suggests that behavioral scientists have attempted to understand human language by studying distantly related birds such as the communicating zebra sparrow.

'I think we humans tend to overestimate our differences,' says Jarvis. He had observed zebra birds singing in the laboratory, starlings singing in trees and thought it seemed very different from what humans do. A year later, he discovered that the connectivity of neural circuits, or the mechanism by which birds make sounds, was very similar to humans.