January 11, 2013
Vocalizations Of Banded Mongoose Similar To Human Speech
Brett Smith for redOrbit.com - Your Universe Online
From songbirds to humans, many animals use complex vocalizations to communicate amongst their own species, and a new study from the University of Zurich found that even the monosyllabic calls of the banded mongoose are structured and similar to our own speech.
The biologists´ report in the latest edition of the open access journal BMC Biology is the first to show animals communicating with sound units shorter than a syllable.
“The example of banded mongooses shows that so-called simple animal sound expressions might be far more complex than was previously thought possible,” the scientists said in a statement.
Because of anatomical limitations, animals only have a select number of distinguishable sounds and calls at their disposal. Some animals, such as whales and birds, are fortunate enough to create complex calls that are fashioned from smaller sound units. These syllables, or “phonocodes,” are repeatedly combined into new arrangements in order to convey different messages.
However, many animals are only capable of making monosyllabic noises to express alarm or to reach out to another individual. Experts have long believed that these simple grunts, squeaks, or squeals had little nuance or complexity about them.
In the new study, biologist Marta Manser and doctoral student David Jansen from UZurich showed that the monosyllabic calls of banded mongooses contain structures that convey different information. They also make the analogy that the mongoose´s sound expression structure bears a certain similarity to the vocabulary of human speech.
The scientists studied the wild, yet habituated banded mongooses at a research station in Uganda. From February 2009 to July 2011, they observed the animals, making detailed behavioral observations and recordings of their calls.
A sonic analysis of these recordings showed that calls lasting between 50 and 150 milliseconds can be interpreted as a single ℠syllable´. The scientists noticed that the monosyllabic calls exhibit various unique vocal signatures. The signatures were then broken down for evidence of individuality and compared to observations of the animals´ behavior.
“The initial sound of the call provides information on the identity of the animal calling,” explained Jansen. The second, more tonal part of the call, he said, indicates the caller´s current activity.
In their report, the scientists concluded that their study on the banded mongoose could open the door for studying the deceptively complex vocalizations of other animals. They also said that future studies should focus on the prevalence of these types of communications in the wild so that their evolution could be tracked and analyzed.
They said the vocal repertoire of the mongoose allowed for greater communication that would benefit the entire community. Banded mongooses are highly social animals that rear their young cooperatively.
The community is typically composed of around twenty adult animals that not only look after their young animals–they also defend their territory and forage as a unit. When the young begin to go foraging with the group, they enter into a sort of mentor-apprentice relationship with an adult animal. These young recognize their mentor based on its unique vocalization.