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Recipes for Perfection
Genes, childhood and absolute pitch
  
By
Edward R. Winstead



Featured Article.

Cheating on Siamak Baharloo's test is impossible. And studying for it is pointless.


The test identifies individuals with perfect pitch—the ability to name a tone without hearing a second tone for reference. A few years ago, Baharloo and his colleagues at the University of California, San Francisco, developed an 80-tone auditory test that appears to be foolproof. People with perfect pitch ace the exam, recognizing 40 piano tones and 40 pure tones as most of us recognize colors. The pace of the test is unforgiving—a new tone sounds every three seconds—and successive tones are octaves apart. This tends to trip up accomplished musicians who are skilled at using reference tones to identify notes but who don't possess what the researchers call absolute pitch.

"I truly believe that there are people who can develop absolute pitch and people who cannot," says Baharloo. In 1998, his group reported that the development of the trait appears to require a genetic predisposition and some form of musical training in childhood. Now, the researchers say they have the strongest evidence yet for the role of genes in the development of absolute pitch: statistical evidence that the trait runs in families.

"We are dealing with a genetic phenomenon," says Baharloo, who compared the frequency of absolute pitch in two populations of musicians and their families. "The pattern of inheritance of absolute pitch is consistent with that of other traits involving one or several genes. It should be possible to map and clone the genes if a sufficient number of families or pairs of siblings can be assembled."


The idea that early musical training is necessary but not sufficient for the development of absolute pitch was supported by the findings, which appear in the September issue of The American Journal of Human Genetics. Most possessors of absolute pitch identified by the UCSF researchers say they began musical training before age six. Many had their earliest musical experiences before they were four years old.

"Why in the world would a four-year-old play the violin or play the piano?" Baharloo asks. The answer he hears most often from parents of children with absolute pitch involves an older sibling's piano lessons: One day after the instructor leaves, a younger sibling with perfect pitch sits at the piano and plays parts of songs from the lesson. "Somehow the parents are observant enough to realize that the kid is also talented," says Baharloo. "They would then get lessons for the younger child."


‘Absolute pitch is a great model for understanding complex human behavior.’

Why the formal musical training needs to occur at an early age remains a mystery. Baharloo suspects that a window exists during childhood when the development of perfect pitch can occur in the brain if a child with right genes is exposed to music. The genetics of absolute pitch might reveal something about how the brain develops as well as about traits.

"My view is that absolute pitch is a great model for understanding complex human behavior," says Nelson B. Freimer, one of the study's leaders. "We have good evidence that absolute pitch involves both genetic and non-genetic factors, and we believe this will be true for most complex traits." Freimer, who is now at the University of California, Los Angeles, says it's too soon to know how many genes might be involved.

Freimer and Jane Gitschier, also of UCSF, have long been interested in absolute pitch as a model of gene-environment interactions because the environmental component of the trait can be defined. When Baharloo began developing the test for absolute pitch five years ago, the literature on the subject was primarily by musicologists or psychologists. For a genetic study, the researchers needed a clear definition of the trait and an efficient way to identify subjects.


‘Absolute pitch is genes and environment’

Like most traits, absolute pitch differs somewhat between different individuals. Some people hear tones in ambient sounds, such as the hum of a refrigerator or a doorbell's ring. One man reportedly knows it's time to change the batteries in his electric razor when the tone of the buzz goes flat. The researchers have focused on finding individuals who achieve nearly perfect scores on the test, believing that having DNA from individuals with a strong form of the trait will make it easier to identify relevant genes later on.

"I don't know how important the stratification of different forms of absolute pitch will be in mapping the genes," says Peter K. Gregersen, of the North Shore University Hospital and the New York University School of Medicine. "My feeling is that it may not be crucial because we have some families with multiple members who have absolute pitch and only some of the members have the most severe form." His group has identified hundreds of possessors of absolute pitch, but the standard is less stringent than the UCSF group's. Absolute pitch is so rare, he says, that using a strict standard could make it difficult to assemble the families needed for a gene hunt.

"The latest study is a very nice and careful demonstration of what we've all been thinking: Absolute pitch is genes and environment," says Gregersen. In the last three years, both he and Baharloo have published surveys with similar results. During the late nineties, the UCSF researchers interviewed more than 600 musicians at conservatories, music schools, and orchestras about their musical training and family histories; they tested perfect pitch candidates using laptop computers and headphones. Baharloo has identified 74 individuals with the most severe form of absolute pitch, or AP-1.


Even among music students, absolute pitch is rare

The current study is the first to include a control group that was selected through a random approach. Inheritance was estimated by comparing the likelihood that siblings would develop absolute pitch in two groups: the families of AP-1 individuals and a control group. The control group consisted of 625 middle and high school students who attended music camp at Florida State University. (The researchers have no way of testing individuals who lack any musical training.) The FSU program was randomly selected from a list of the first ten summer music camps identified in an Internet search using 'summer music camp' as the key word.

All of the 625 students were surveyed and tested. Although students heard the tones over loudspeakers rather than through headphones, Baharloo determined that this probably did not color the results. From the surveys, Baharloo identified 139 students who reported musical training by age six. Four of these students turned out to be AP-1.

"It's clear that absolute pitch the way we describe it is not very common even among music students," says Freimer. "At this point we have identified about ten families that are suitable for the genetic study."

Baharloo emphasizes that a gene hunt is possible now largely because of the test. He recalls that during the survey he received phone calls from professional musicians who said they had perfect pitch even though they took up music after childhood. Baharloo respectfully suggested that this was not possible, according to his data. "These were talented musicians, some of whom were playing in well-known orchestras," he says. If they persisted, Baharloo let them take the test: "In each case, the musician stopped after a few questions. They'd say, 'I don't have it,' and give up."

"The test has made all the difference," he says.

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Baharloo, S. et al. Familial aggregation of absolute pitch. Am J Hum Genet 67, 755-758 (September 2000).
 

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