Singing Syllables: Canaries Chime in on the Nature vs. Nurture Debate
Similar to the way adult humans structure their speech, adult song birds string together series of syllables into repetitive units called phrases and then into larger units that convey meaning to others of their species. A song bird's “phrases” (repetitive syllables) are like our words, and the order that the phrases are delivered can be likened to the syntax of our sentences. In this month's issue of Science , behavioral scientists and mathematicians teamed up to report on what they have learned about this process of song acquisition in canaries. Their work has some surprising and interesting implications for the age-old nature vs. nurture debate.
The scientists isolated canaries from birth, removing any song influence from adult members of their species. The birds were only allowed to hear an artificial canary song full of real adult canary syllables, jumbled into unnatural phrases. It is as if the phrase “canaries singing” was randomized into “can ing sing ies ar.” Even though these artificial songs lacked phrasing, violating a “rule” of adult canary song, the young birds learned and imitated them. Thus, song acquisition during youth appeared to be free of genetically-imposed rules and programs.
Because the scientists wondered whether this behavior would change during adult development, they promoted maturation by treating the birds with testosterone, a hormone which is normally made in singing birds at the onset of adult development. Instead of singing gibberish phrases like as they had before, these birds began ordering their words into phrases that resembled those found in normal adult canary song, even when no adult song was present as an influence. It seems that testosterone activated some genes that controlled how the birds learned song.
The way a canary or a human learns, arranges, and executes syllables is the basis of vocal communication or speech. It was once thought that vocal learning might start with an in-born program for vocal development which is later relaxed to incorporate the models and feedback that are heard by the growing learner. Instead, this study suggests that vocal learning might start with a period of experimentation and slowly add in programmed influences. Research like this continues to fuel interesting conversations in the science community and the general public as to how much our environment and our genetic make-up matter in developing certain traits and skills.
Primary Research Article:
Gardner, TJ, Naef, F, and Nottebohm, F. “Freedom and Rules: The Acquisition and Reprogramming of a Bird's Learned Song” Science May 13, 2005
Background on the Nature vs. Nurture Debate and on Language Acquisition:
http://encyclopedia.thefreedictionary.com/Nature%20vs%20nurture
