Wednesday, October 29, 2008

Nature AND Nurture? - "It's in the Genes!"

Genome-wide linkage scan for loci of music aptitude in Finnish families:
evidence for a major locus at 4q22
K. Pulli, K. Karma, R. Norio, P. Sistonen, H.H.H. Goring, I. Jarvela
Journal of Medical Genetics 2008 45: 451-456

Review and Response by John Picone

This paper was the focus of discussion among interested students and teachers at a monthly gathering hosted by the McMaster Institute for Music and the Mind. Dr. Steven Brown chaired the meeting.
The seminal question is a simple one: where does musical perception and performance come from? Why is it that some people are “musical” and others not so? Is it “nature” or “nurture”?
The objective of this study is to “unravel the biological background of music perception using molecular and statistical genetic approaches” (p. 451).
The paper sets the stage for the study with several significant observations.
Music is an ancient and universal feature across all human societies. The ability to appreciate music requires no explicit training. The universality of musical behaviour and validity of common rules such as use of octave-based scale systems and preference for consonance over dissonance in nearly all types of music can be seen as evidence for innateness. Rules have arisen independently in isolated cultures, and some of them also apply to the music perception of non-human species. This implies that these rules have their basis in brain organization rather than in culture (p. 451).
The researchers point out the difference between adult and infant perception of music: “Adults’ abilities to perceive music are somewhat dependent on culture, whereas infants seem to possess a more generalized capability, which obeys the aforementioned universal rules of music” (451). They note that this innate ability can be modified environmentally. “A fundamental question is whether, or at what level, this ability is genetically determined” (451).
The paper notes that “neuroimaging and neurophysiological studies have shown that listening to and/or playing music has multiple effects on brain structure and function, suggesting a biological effect,” but that “the molecules mediating these responses remain uncharacterized” (p. 451). While “professional musicianship clusters in families,” the subject of the debate remains “how much this aggregation is due to genetic or environmental factors” (p. 451)
Musical ability varies between individuals, and seems to be expressed at the population level in such a way that both extremes (extremely capable or incapable individuals) are rare, and hence most individuals express moderate ability. This is a typical feature of a complex trait influenced by several underlying genes, environmental factors and their interactions. We hypothesized that music aptitude is an innate cognitive ability that is partly under genetic regulation and serves as a basis for music expertise in a favourable environment (p. 451).
The methods used by the researchers are as follows:
15 Finnish multigenerational families (with a total of 234 family members) were recruited via a nationwide search. The phenotype of all family members was determined using three tests used in defining musical aptitude: a test for auditory structuring ability (Karma Music test; KMT) commonly used in Finland, and the Seashore pitch and time discrimination subtests (SP and ST respectively) used internationally. We calculated heritabilities and performed a genome-wide variance components-based linkage scan using genotype data for 1113 microsatellite markers p. 451).
The study arrives at three significant conclusions:
Three tests of musical aptitude, an auditory structuring ability test (Karma Music test; KMT), Seashore test for pitch (SP) and for time (ST) showed substantial heritability in 15 Finnish families.
Significant evidence of linkage was obtained for chromosome 4q22 (LOD 3.33) and suggestive evidence of linkage for 8q 13-21 (LOD 2.29), with the combined music test scores using variance component (VC) linkage analyses in the Finnish families.
Our results show that there is a genetic contribution to musical aptitude that is likely to be regulated by several predisposing genes/variants (p. 456).
There were two aspects of the study itself that intrigued me. The first had to do with the way family members in the study were grouped by age: under 9 years of age; between 9 and 11 years of age; over the age of 11. The study offered no rationale for this grouping. What was significant to me was the fact that, while the test scores in the youngest group were notably lower than the scores in the other two age groups, the scores in the middle group – ages 9 to 11 - were the same as the scores in the older group. The researchers note that these results are in agreement with previous studies and that such data suggest that “the maturation of the brain for musical aptitude occurs relatively early” (p. 452).
Is there a magic age at which to begin music lessons? Providing a favourable environment to work with a genetic predisposition to be musical?
The second aspect of the study that caught my attention had to do with the results of the tests with respect to the musical training of the family members. The participants were categorized into three groups: no musical training, amateur, and professional. My instinct told me that those at the professional level, with many years of musical training informing their musical ability, would naturally score higher on the tests. Such was not always the case. As the study points out, “The KMT is devised to measure auditory structuring in a way that minimizes the effect of training and/or culture” (p. 452). Test scores reveal that “musical training is not a necessary condition for a high score” p. 453). At the same time, “although there was a clear connection between musical training and the scores, the source of this relationship was not revealed by the scores. Training may have driven performance and/or performance was driven by selection because substantial innate musical aptitude is necessary n order to become a successful professional musician” (p. 453). As one of the group pointed out, people who sing out of key can be trained to sing on key.
The most engaging point of discussion following Dr. Brown’s presentation of the study centered on the influence of culture on one’s musical ability. Dr. Trainor pointed out that family members not only share genetics, but also environment. An interesting study, then, would be to look at the musical ability of adopted or foster children who share a musically rich environment, but not the genetics of their “parents.”
Finally, the discussion surrounding the study prompted me to look at my own musical ability and wonder just how it is that I’m the only one in my extended family who has made a career out of music as a high school music educator and conductor. Both my siblings and many of my cousins took piano lessons, but none pursue their music today. In sharing some of this with my parents, I discovered that making music was very much part of their environment as children, that piano, violin and accordion were played by my grandparents and great grandparents. I’m told I was sung to as much as I was read to as a young child. And how could I ever forget the Christmas my sister and I received “one big present instead of many little ones”: an RCA Victor record player with a single album by Mario Lanza featuring “O Holy Night.” I can still hear it today!

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