Understanding the genetic basis of our vocal system can shed light on the evolution and development of human language.
Previous genetic studies on the human vocal system have primarily focused on voice or speech disorders and syndromes. Some researchers have looked at species like songbirds and vocal learning bats to gain insights into speech. However, there is still much to learn about the genetics of voice and vowel acoustics in humans.
In a groundbreaking study, researchers conducted a genome-wide association study (GWAS) on voice and vowel acoustics using speech recordings and genetic data from 12,901 Icelanders. Iceland, with its genetic and linguistic homogeneity, provided an ideal research site for this study. The goal was to identify sequence variants associated with voice and speech variation and uncover the genetic architecture of the human vocal system.
Acoustic measures of speech, such as voice pitch and vowel formants, were used to investigate the genetics of the human vocal system. Voice pitch refers to how deep or high a person’s voice sounds, which is influenced by the rate of vocal fold vibration. Voice pitch is not only used to express emotions and convey linguistic information but also to convey perceptions of body size and other characteristics. Studies have shown that average voice pitch correlates with hormone profiles, physical strength, reproductive success, and perceptions of attractiveness and dominance.
Voice pitch variability, on the other hand, captures intonation in speech and may also play a role in mate choice. The primary measures of the vocal tract filter are known as formants, which are vocal tract resonant frequencies that distinguish vowels. Vowel formants are modulated by speakers to amplify perceptions of size and masculinity/femininity, highlighting their social function beyond linguistic content.
Twin studies have suggested that voice pitch and other voice characteristics have genetic influences. Components of the vocal tract are also known to be heritable. However, large-scale genetic studies of voice and vowel measures had not been conducted until this study.
The ABCC9 gene is one of the genes that encode for the ATP-binding cassette (ABC) transporters, a large family of proteins that move various substances across cell membranes. The ABCC9 gene is also known as SUR2, and it plays a role in forming ATP-sensitive potassium channels (KATP) in different types of muscle cells, such as cardiac, skeletal, and smooth muscle cells. KATP channels are important for regulating the electrical activity and contraction of these cells, and they can be modulated by drugs such as sulfonylureas, which are used to treat diabetes.
One of the interesting aspects of the ABCC9 gene is that it has been linked to some rare genetic disorders that affect the voice and other features. For example, Cantu syndrome is a condition characterized by excessive hair growth, distinctive facial features, heart defects, and a deep voice.
This syndrome is caused by mutations in the ABCC9 gene that make the KATP channels more active, leading to reduced muscle tone and altered blood flow. Another condition associated with the ABCC9 gene is familial atrial fibrillation 12, a type of irregular heartbeat that can increase the risk of stroke and heart failure. This condition is caused by mutations in the ABCC9 gene that make the KATP channels less active, leading to increased excitability and arrhythmia of the heart muscle cells.
The ABCC9 gene is therefore a fascinating example of how a single gene can have multiple effects on different tissues and organs, and how genetic variations can influence both health and phenotypic traits such as voice quality. Further research on this gene may reveal more insights into the molecular mechanisms and potential therapies for these disorders.
ABCC9 is involved in regulating cellular functions in multiple tissues, including hormone secretion, vascular tone, cardiac muscle contraction, and synaptic transmission. Although ABCC9 had not been directly linked to voice or speech phenotypes before, rare mutations in the gene have been associated with a disorder called Cantú syndrome, which includes speech delays and hoarse voice as symptoms.
ABCC9 mutations have also been linked to dilated cardiomyopathy, atrial fibrillation, and intellectual disability myopathy syndrome.
The mechanism by which ABCC9 influences voice pitch is not yet fully understood. The adrenal glands produce steroids that influence voice pitch, and ABCC9 expression in the adrenal gland was associated with the identified variants.
Another possibility is that the variants affect the vocalis muscle in the vocal folds or muscles in the vocal tract. Elastin and collagen, critical proteins in the vocal folds, are also involved in vascular stiffness, and ABCC9 variants may affect these proteins.
The study also explored the heritability of voice and vowel measures by estimating the genetic and environmental contributions to individual variation. The researchers found that both voice pitch and vowel formants showed significant heritability, indicating that genetic factors play a role in shaping these vocal characteristics.
Additionally, the study investigated the genetic correlation between voice and vowel measures and various traits and conditions. They found a positive genetic correlation between voice pitch and smoking behavior, suggesting a potential link between genetic factors influencing voice and the propensity for smoking. However, the exact nature of this relationship requires further investigation.
Furthermore, the researchers discovered a negative genetic correlation between voice pitch and educational attainment, indicating that genetic factors associated with a higher-pitched voice may be related to lower educational achievement. This correlation could be influenced by various factors, including social perceptions and biases associated with voice characteristics.
It’s important to note that while the study provided valuable insights into the genetic basis of voice and vowel acoustics, there are limitations to consider. The research was conducted on a specific population (Icelanders), which may not fully represent the global genetic diversity in voice and speech characteristics. Replication studies in diverse populations will be necessary to generalize the findings.
Further research is needed to fully understand the mechanisms by which these genetic variants influence the human vocal system and how they contribute to language development and communication.
reference link : www.science.org/doi/10.1126/sciadv.abq2969
