Science & Technology (Commonwealth Union) – Communication methods from ancient times have always fascinated modern generations. Questions have remained to how much inspiration humans drew from animal communication.
From the songs of whales to the roars of lions, animals have developed ways to project their voices over long distances so that allies – and sometimes rivals – can hear them.
Each call carries a message such as “Come here!”, “Stay away!”, “There’s danger nearby!”, or “Want to spend time together?”
The question remained as to how communication was across the miles.
Researchers from the University of New South Wales (UNSW) investigated this question by examining the evolutionary factors behind long-distance calls in 103 mammal species worldwide, including lions, blue whales, koalas and even humans.
The study, published in the Journal of Mammalian Evolution, combined findings from 81 separate research papers and revealed a notable global pattern: the forces shaping vocal evolution in the ocean are different from those influencing animals on land.
Dr Ben Walker, lead author of the study and evolutionary ecologist at UNSW indicated that atmospheric factors generally played the most significant evolutionary role in deciding how far land mammals can message, but biology – specifically, size – was the most significant influence for underwater mammals.
“In other words, land mammal calls have evolved mainly in response to environmental pressures, while aquatic mammal calls evolved in response to changes in body size.”
Underwater, the trend was straightforward: the larger the mammal, the farther its calls could travel.
At the top of the scale are blue whales, weighing roughly 150 tonnes, whose songs can carry as far as 1,600 kilometres under ideal conditions.
At the opposite end are otters, which weigh around 28 kilograms and produce calls that reach only about one kilometre.
On land, however, the pattern becomes more complicated. The main factor influencing how far a mammal’s call travels is the size of its home range—essentially the area it occupies. Yet this distance is also strongly shaped by the type of habitat the animal lives in, the purpose behind the call, and whether the species is social or tends to live alone.
“Mammals that call in closed environments, like rainforests, have evolved to have relatively further calls than mammals in open environments, like savannahs. This really surprised me, as I was expecting the opposite.”
For instance, territorial calls—sounds used to warn others to stay away from an animal’s area—were found to carry over longer distances than other types of vocalisations.
Species that live in social groups, such as elephants, were also able to communicate across
Dr Walker indicated that the environment that land mammals inhabit also turned out to be a significant factor, though not in the way they originally predicted.
Human-driven changes to habitats are already influencing animal behaviour worldwide. Dr. Walker stated that bats have been seen using echolocation less during music festivals and that noise from ships can stress whales out.
The new study also gives us some ideas about how the mammals studied might react—or even have trouble—when they face environmental pressures in the future.
Dr. Walker said that their finding that land mammals that live in dense, closed habitats have calls that travel longer distances than those that live in open environments is important. He also said that if forests or other closed habitats are cleared, those calls might go farther than the animal wants, which could be dangerous.
Earlier studies have found that marine mammals are showing reduced growth as a result of human whaling and environmental pressures.
Dr Walker explains that this decrease in size could also influence how effectively these animals communicate.
He highlighted the fact that since 1981, the maximum body length of North Atlantic right whales has fallen by 7.3%.
