Some Animals Long Believed To Be 'Mute' Do Make Sounds: Study

For instance, many turtles, which were previously thought to be mute, have been found to show broad and complex acoustic properties.

A new study has found that some animals, including turtles, that were long believed to be mute, do make sounds. 

Source : Getty

Various vertebrates use vocalisations as a resource for communication. Some examples include singing birds, barking dogs and croaking frogs. Vocalisations are necessary because they play a fundamental role in parental care, mate attraction and various other behaviours. However, not much is known about when and at what stage in the evolutionary history of vertebrates this behaviour first appeared. Knowledge about the evolutionary origin of acoustic communication is often plagued by missing information from key groups that have not been broadly studied. A new study has found that some animals that were long believed to be mute, do make sounds. 

Land vertebrates exhibit acoustic abilities

An international team of researchers led by University of Zurich analysed species that have never been accessed before. The team found evidence of vocal recordings and behavioural information accompanying sound production for 53 species of four major clades of land vertebrates, namely turtles, tuataras, caecilians and lungfishes.

Some animals that have long been thought to be mute do make sounds

The study describing the findings was recently published in the journal Nature Communications.

In a statement released by University of Zurich, Gabriel Jorgewich-Cohen , one of the authors on the paper, said these recordings, along with a broad literature-based dataset including 1,800 different species covering the entire spectrum shows that vocal communication is not only widespread in land vertebrates, but can also be seen in several groups previously considered non-vocal. Evidence shows that these animals have acoustic abilities. 

For instance, many turtles, which were previously thought to be mute, have been found to show broad and complex acoustic properties.

Vocal communication originated more than 400 million years ago

The researchers combined relevant data on the vocalisation abilities of species like lizards, snakes, salamanders, amphibians and dipnoi with phylogenetic trait reconstruction methods to investigate the evolutionary origins of acoustic communication in vertebrates. Phylogenetic reconstruction describes evolutionary relationships in terms of relative recency of common ancestry. 

The researchers mapped vocal communication in the vertebrate tree of life, using data from well-known acoustic clades like mammals, birds and frogs. 

Marcelo Sánchez, who led the study, said the researchers were able to reconstruct acoustic communication as a shared trait among these animals, which is at least as old as their last common ancestor that lived approximately 407 million years before present. This means that vocal communication among animals originated more than 400 million years ago. 

Vocal communication did not evolve multiple times 

The morphology in hearing apparatus and its sensitivity, and the vocal tract morphology vary considerably among vertebrates. Therefore, scientists believed that acoustic communication evolved convergently, which means that analogous structures have similar functions, but were not present in the last common ancestor of the group. 

However, according to researchers from University of Zurich, the evidence which supports the hypothesis that acoustic communication underwent convergent evolution lacks relevant data about key species that have so far been considered mute or non-vocal. 

Sánchez explained that the study results show that acoustic communication did not evolve multiple times in diverse clades, but has a common and ancient evolutionary origin.