As we said, scientists believe perfect pitch is at least partly a learned function, or one that combines genetics, exposure and musical training during a certain developmental stage [source: Wertheimer].
Some compelling evidence for that idea comes from a randomized, double-blind study for which a group of 24 young men were either given a dose of valproic acid, an HDAC inhibitor, or a placebo. During the 15-day treatment, the men were shown training videos that taught them to identify six different pitch classes with six different proper names. (That was so the activity was fresh to those with and without a musical background -- though none had training early in life -- and to make sure it deviated from sounding too much like a musical theory lesson.)
After the 15 days, the subjects were tested. They were played a musical note and asked what name the note was associated with. After a few weeks of no treatment or training, the subjects switched and those given the placebo were administered valproic acid (and vice versa). The results proved pretty cool. Those who first went through training on valproic acid had a significantly higher instance of correct answers (5.09) than the placebo (3.50) -- and those their age, in general [source: Gervain et al.]. However, participant who took the valproic acid during the second phase of the experiment (after taking the placebo during the first phase) didn't do so well, and the study hypothesizes that there could be a "memory conflict," meaning that it was harder to keep track of a second set of proper names and corresponding pitches after previously learning a different set [source: Gervain et al.].
The research suggests that the valproic acid recreates a time of plasticity in the adult brain that's normally last seen during the earlier critical period -- and that idea has farther-reaching effects than simply allowing old folks to learn perfect pitch. The study might indicate that by inhibiting HDAC with a medication like valproic acid, you can learn all sorts of things normally reserved for the "critical period," like language acquisition. No longer will your 5-year old niece mock you for your inability to keep up with Spanish lessons on "Sesame Street."
This doesn't mean we should all rush out to collect valproic acid and a Mandarin tutor. The off-patent drug is normally prescribed for seizures or as a mood stabilizer, and can cause serious liver damage [source: National Library of Medicine]. In addition, scientists who conducted the study caution that critical periods developed for a reason; being too quick to circumvent or supplement that part of the brain's development might have unintended consequences, like erasing earlier "critical period" acquisitions [source: Wertheimer].