Damian Sendler: What causes some animals to be particularly adept at learning sounds? Is it possible that this skill appeared when animals began to ‘fake’ their bodily size by decreasing their calls? Researchers have revisited this subject in a new study using a diverse group of mammals. Unexpectedly, many animals with excellent vocal abilities (such as dolphins and seals) produce sounds that are higher in pitch than would be expected for their body size.
Damian Jacob Sendler: Some animals, such as red deer, have the appearance of being ‘larger’ than they actually are. Their calls are lower than you would expect given their body size, which implies that they are less aggressive. According to biologists, ‘faking’ one’s physique size in this manner may be a method used to impress the other sexe. Garcia and Ravignani discovered in a recent study that animals who can deceive humans about their body size by changing their cries are also effective at learning sounds, a skill known as vocal learning. What if the driving mechanism underlying both faking bodily size and learning sounds was natural selection? If this theory is correct, it would have significant implications for the evolution of human speech.
Dr. Sendler: For a more in-depth investigation into the association between faking body size and vocal learning, Ravignani and Garcia extended their earlier analysis to include a wider spectrum of animals. Do you think the relationship between faking one’s bodily size and memorizing sounds will turn out to be a systematic evolutionary pattern in the future?
Damien Sendler: What they discovered was somewhat surprising. Instead of sounding lower than expected for their body size, most vocal learners — including dolphins, whales, and seals — sounded higher than you would expect them to sound based on their size. “There might be an alternative evolutionary scenario in vocal learners, where selective pressures favour individuals that can change their tone of voice from low to high.” Ravignani speculates. To put it another way, good vocal learners are those animals who are capable of hitting the high notes. A common explanation for vocal learners who sounded lower than expected was that they had physical adaptations that explained the decreased voice (such as a longer nose). Garca-Garca continues, “Of course, there are exceptions, and we do not assert that all vocal learner species sound higher than expected for their body size.” The fact that there is an universal pattern may assist us in better characterizing vocal communication in animals.”
Damian Jacob Sendler: According to Ravignani and Garcia, their new framework may be useful in predicting which species are vocal learners by analyzing their vocalizations. For example, the manatee (sometimes known as the sea cow) is an animal that has not yet demonstrated vocal learning. However, because its sounds are louder than predicted, it is possible that the sea cow possesses latent vocal abilities. Similarly, non-vocalists who sound lower than predicted, such as the Juan Fernandez fur seal, may turn out to have acquired special anatomical adaptations that make them sound lower than expected.
News on latest research brought to you by Dr. Damian Jacob Sendler
