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What You Speak is Written in Genes

Is speaking Cantonese determined by our genes? A research group led by Prof. Patrick Wong, Stanley Ho Professor of Cognitive Neuroscience of the Department of Linguistics and Modern Languages and director of Brain and Mind Institute, discovered that participants with a specific genotype of the brain-growth related ASPM gene are better at perceiving lexical tone in Cantonese. As most Chinese people have the genotype that favours lexical tone processing, they adopted lexical tone in their language, with such trait staying on throughout language evolution.

Cantonese uses pitch to distinguish word meanings. For example, /si/ spoken in a high pitch means ‘teacher’ (師 [si1]), while in a low pitch it means ‘time’ (時 [si4]). In 2007, British linguists Dan Dediu and D. Robert Ladd put forward the genetic-biasing hypothesis of language evolution, which argues genes predispose one to certain linguistic characteristics. To prove this claim, Prof. Wong studied the association between these genes and the perception of lexical tone in Cantonese speakers. Since 2015, the team had recruited more than 400 native Cantonese speakers to take listening tests on Cantonese tone and musical pitch, among others. Saliva samples of theirs were collected for genetic testing by Prof. Richard Choy, associate professor of the Department of Obstetrics and Gynaecology and deputy director of the Prenatal Genetic Diagnosis Centre at CUHK. Results found that about 70% of participants carry the TT genotype of the ASPM gene, and these individuals are better able to perceive Cantonese tones. For the remaining 30% who possess another genotype, their performance is less brilliant.

Yet, the current study also shows that those without the said genotype may improve their tone perception through musical training. As Chinese speakers with developmental language disorder and autism spectrum disorder often have tone perception deficits, screening for ASPM could be an avenue for early detection of communication disorders as well as a clinical marker for early intervention.