Some animals learn how to 'mimic and sound' bigger to increase their chances of attracting mates, finds study
Some animals use the art of deception to increase their odds of reproducing. By sounding louder, they can make themselves appear bigger to others. A new theory suggests that these organisms do so by mimicking other individuals, making them skilled learners. It could also explain how humans picked up speech.
Animals use sounds to assess the size of another individual. It could inform them about a potential rival or a mating partner. It is therefore expected that these signals convey an accurate impression of body size, which is called "honest signaling", Dr Andrea Ravignani from the Max Planck Institute for Psycholinguistics, and Dr. Maxime Garcia from the University of Zurich told MEA WorldWide (MEAWW).
However, not all of them give out honest signals. There are also various cases where individuals will try to fake their body size by changing their sounds. Within the animal kingdom, researchers have found animals whose vocals do not match their size. "For instance, howler monkeys sound much bigger than other similar-sized primate species. The same goes for red deer males. And Koalas' mating calls, which sound like tractors, giving the impression of a huge animal for those who have never heard that sound before," they added. There is more: some animals are even capable of mimicking sounds. Seals, dolphins, bats and elephants are some examples.
Garcia and Ravignani wondered whether animals who fake sounds could also learn to make new ones. So they studied sounds and body size of 164 different mammals, including mice, monkeys, subantarctic fur seal and the Amazonian manatee. They combined methods from acoustics, anatomy and evolutionary biology to compare the different types of animals.
Their analysis led them to propose that animals who fake their vocals could be capable of learning new sounds. These changes may boil down to reproductive success, allowing them to pass on these tricks to the future generation. Biologists call this sexual selection. One "will positively select a partner that sounds bigger because it often correlates with reproductive advantages for their offspring," they noted.
Animals can escape vocal shortcomings through enhanced control over their apparatus that produces sound. Garcia and Ravignani think the theory could apply to humans as well. "Speculatively, it brings us closer to understanding human speech evolution: our ancestors may have learned how to speak after learning how to sound bigger or how to hit high notes". Previously, researchers suggested that sexual selection may have driven the evolution of human speech.
The team is hoping to expand the theory. "We want to expand our theory to take into account other evolutionary pressures, not just sexual selection," added Ravignani. "We also want to replicate our preliminary findings with more mammals and test whether our ideas also apply to birds or other taxonomic groups." The authors said that they offer a potential evolutionary scenario that could explain the emergence and maintenance of vocal learning within mammals. "By no means, this discards other alternative scenarios already existing. Our analyses are preliminary and the conclusions need to be drawn carefully," they acknowledged.
The opinion is published in Biology Letters.