Songbirds and humans both learn language by listening to and imitating others!
Zebra finches (Taeniopygia guttata) are a very common bird found almost in all parts of Australia. They are native to Australia, but they were also introduced in Puerto Rico and Portugal and can now be found there as well.
Australian zebra finches, which weigh less than half an ounce, are known to be loud singers. But only the male has the singing ability; the male uses his boisterous songs to attract females. However, both males and females can produce calls; they produce about 10 different types of calls. The species is well known for being the first wild bird whose genetic code has been cracked, after the chicken, and some 800 genes have been found, which have seemed to have a link with the song learning.
The red-beaked young males usually start vocalization by babbling, much like a human toddler, and learn songs by imitating their elders. Similarities can be found in the songs of these birds, a fact stated by Aristotle over 2,000 years ago in his “Historia Animalium (History of Animals).” The sweet twittering songs comprise only a small number of 3 to 8 distinct syllables; short, buzzy sounds with a distinctive structure and repeat in a fixed order.
Young songbirds make their own song that is the “subsong,” and later on, when tutored by a male adult, they mimic their song, and a sophisticated combination of both songs is made that is used for the rest of their life. Songbirds hone their use of language over the critical period of the first sixty to hundred days of life, just like humans learn to speak before puberty, thus providing an incredible avian model system for understanding and investigating the neural bases of voice learning.
Songbirds have been the focus of about 800 papers and 30 research papers in Nature and Science. Experiments are being done on the brains of these birds to find out as to what happens in the brains of these birds as they learn how to sing. These finches share many genes with humans and can be promising to understand and cure many of the voice and speech disorders in humans, such as stuttering, autism, strokes, and Parkinson’s disease. This gives extra relevance to the finches’ genome.
Previously it was thought that some 100 genes are involved in the short song learning, but now it seems the number is close to an astonishing 800. Researchers at the Washington University School of Medicine in St. Louis found that during this learning period, a large number of genes in the brain get turned on or off. Many other unusual genes are assigned this particular task, and scientists think those genes are the reason behind the successful vocalization in a limited number of species such as bats, birds, elephants, whales, and humans.
Most significantly, the research has shown that the non-coding part of the gene is also very helpful in the process. So this “junk” part of the gene plays a vital role in the animal kingdom.
We will now look at how the genes affect song learning and how it is similar to humans. It should be mentioned beforehand that only males have the ability to sing. This is because the testosterone in the males enters the brain and is converted into estradiol, and this estradiol brings about chemical changes.
The team of international researchers at UCLA explains the molecular basis of the whole process. In the songbirds, there is a speech gene called the Fox2P. The gene, first identified in 2001, is responsible for the production of proteins that affect the coordination of mouth movements and speech, thus plays an important role in language development. Later in 2004, this master gene was discovered in the neurological “Area X” in the basal ganglia, beneath the finches’ brain’s cortex.
As the bird sings, the activity of the Fox2P decreases. This causes a change in thousands of other genes that allows the bird to sing. The change in the Fox2P makes two proteins, one is the larger one, and the other is a smaller one. The larger one brings about the change in the other gene, and the function of the other gene is still a mystery.
To check the hypothesis if this gene activity really brings about the changes that allow birds to sing, the researchers used gene therapy and changed the Fox2P with another version of the gene that did not change the level of Fox2P in area X of the brain. And the result was impaired song learning. Scientists also did the same for the small protein; they used gene therapy. It didn’t impair the song learning but reduced the changes in the learned song. To explain it simply, the genes around the area X of the brain can be seen as the musicians in an orchestra, and the Fox2P is the conductor, coordinating the genes into a beautiful symphony.
The young songbirds also need a stimulating environment and parental motivation for proper and better song learning. Associate Professor from Cornell University, Dr. Michael Goldstein, showed through his experiments that when the mother gives positive feedback by feeding or touching the chick with its wings or beak, the young chick takes it as a reward and improves its unclear sound patterns into a more adult-like song.
Australian zebra finch; a model for human speech disorders
Many animal models have been used to decipher cures for human diseases and disorders. Now the intriguing part about the zebra finches is that the speech gene, Fox2P is also present in humans, and the defect in the long protein produced by the Fox2P is the reason for many of the speech disorders in humans.
But generalization of the results obtained from finches on human beings is not easy because humans are way more complex to study, and ethical limitations surround the study of human babies. Therefore, scientists have turned towards humble zebra finches to look for answers.
The process of song learning on a molecular level is poorly understood. If understood by using the finches and somehow applying them to humans, this research can lead to a greater molecular understanding of song learning. Many new treatment options might be available for people with disorders, like drug therapies that repair or mitigate the effects of the defective gene. We hope that these researches will bear fruit, and there will be a better understanding of speech which will help cure many with serious speech disorders.
Nida Riaz is a freelance blogger based in Pakistan. She started writing about her passion for the environment when the world came to a stop in early 2020.