A Web-based, perfect pitch test reveals new details about musical ability.
Decoding perfect pitch. I'm Bob Hirshon and this is Science Update.
What note is this?
[Middle C tone]
If you said middle C, you may have perfect pitch: the ability to name a musical note with no reference point. Thousands of people have taken an elaborate version of this test over the Internet, and human geneticist Jane Gitschier at the University of California at San Francisco studies the results. She's found that generally, people either have perfect pitch or they don't.
There are people who have incredible pitch-naming ability at one end of the spectrum, and at the other end there's a population who are randomly guessing.
One possible explanation is that the talent has a very simple genetic component, perhaps even a single gene. The study also found that perfect pitch deteriorates with age, and that G-sharp is the toughest note to identify.
I'm Bob Hirshon, for AAAS, the science society.
Making Sense of the Research
Perfect pitch is a very rare trait; most musicians don't have it. With enough training, almost anyone can develop good relative pitch: that is, the ability to identify notes if given a starting tone, or reference point. For example, if someone plays middle C on the piano and tells you which note they're playing, you could use relative pitch to name the notes played after that.
While relative pitch can be learned and developed with practice, so-called "perfect" pitch, or absolute pitch, seems to be more innate. For example, it runs in families: Gitschier's team has found that among people who have early musical training, siblings of people with absolute pitch are 15 times more likely to have absolute pitch themselves than people with no family history of absolute pitch. It's also very difficult, and perhaps impossible, to learn absolute pitch as an adult.
However, absolute pitch doesn't appear to be purely genetic either. People who had musical training before age 7 are much more likely to have absolute pitch than people who didn't. Absolute pitch also appears to be much more common among native speakers of tone languages, such as Chinese, in which the pitch of a word conveys part of its meaning. If perfect pitch were controlled by genes alone, then it would be equally common among musicians and non-musicians, and among speakers of all languages.
Gitschier's research doesn't actually involve any genetic testing. Rather, she uses the data from her very large sample size (over 2,000 subjects) to make inferences about the genetic basis for absolute pitch. Her most relevant observation is that people fall into two general categories: those who have perfect pitch, and can name most or all of the notes in the test accurately, and those who don't have a clue. There are some people who fall in the middle; Gitschier suspects that these tend to be trained musicians with very good relative pitch. But they are in the minority.
From this information, Gitschier concludes that there may be only a few, or even one single gene, involved in perfect pitch. Why? Well, imagine if the opposite were true: that many different genes work together to determine whether someone has perfect pitch or not. For the sake of this example, let's say 50 genes are involved. If that were true, then some people would have all 50 genes that support absolute pitch; others might have 40, 23, 7, and so on across the spectrum. This would probably result in a broad range of absolute pitch skills within the population, from excellent to good to fair to poor and everything in between. On the other hand, if only one gene is involved, the outcome might be more like a coin flip: either you have it or you don't.
The coin flip scenario is much closer to the data that Gitschier has collected. However, Gitschier doesn't suggest that genes alone can give you perfect pitch. She believes that it requires a combination of the right genes and the right environment—in other words, early musical training—to let those genes flourish. Without musical training, a person with the gene for absolute pitch would be like a person with great genetic intelligence who never learned to read. Even a genetic genius might find it hard to learn to read as an adult, compared with the average six-year-old. That's because as we age, our brains become less flexible in their potential to acquire completely new skills.
The next step in solving this puzzle would be to study genetic samples from people with absolute pitch and people without it. If Gitschier's hunch is correct, this might be easier than some scientists might have expected: the fewer genes that are involved in a trait, the easier those genes are to identify. So we may not be far off from finding the "secret ingredient" in DNA that leads to this remarkable musical ability.
Now try and answer these questions:
- What is the difference between absolute pitch and relative pitch?
- How did Gitschier use the data from her survey to draw inferences about genetics?
- Using Gitschier's conclusion that people "either have absolute pitch or they don't," create a rough line graph plotting absolute pitch score (on the horizontal axis) against the number of people who might have achieved that score (on the vertical axis). (Assume that an absolute pitch is more common among people who take the test than in the general population.) You don't need to look up the actual numbers; just try to estimate the general shape of the curve. What does the graph look like?
- Do the same for a scenario in which absolute pitch is controlled by a complex combination of genes. How would that look? Compare it to the graph you created in answering question #3. How are they different?
You may want to check out the September 21, 2007, Science Update Podcast to hear further information about this Science Update and the other programs for that week. This podcast's topics include: why the flu strikes in winter, the genetic code of one species found inside another's, salamanders that are too fat to be eaten by predators, why some of us have perfect pitch and others fall flat, and the effects of pastries on blood sugar.
Learn more about this research, and take the perfect pitch test yourself, at the site for the University of California's Absolute Pitch Study.
Who Am I? from the United Kingdom's Science Museum, is a brief, picture-based tour about genes. Included are sections on human behavior, genetic health, and the study of DNA.
National Geographic News includes articles about other traits that may be controlled by only one or a few genes, including human longevity, a human biological clock disorder, "toy" dog body size, and ant colony formation.