By Dr. Becker
Scientists are uncovering increasingly fascinating details about the complex “languages” used by other species. Mice, for instance, use high-pitched sounds called “ultrasonic vocalizations,” which are normally undetectable to humans.
In the video above you can listen in as the researchers used special microphones to record male mice singing to woo their mates.1 The first part of the video shows a male mouse “singing” in response to smelling female urine.
The song is loud and complex, likely because he’s trying to lure her in. In the second part, a female mouse is placed next to the male. While he continues to sing, his song changes to a simpler, quieter song.
Study author Erich Jarvis, an associate professor of neurobiology at Duke University and a Howard Hughes Medical Institute investigator, explained:2
"We think this has something to do with the complex song being like a calling song, and then when he sees the female, he switches to a simpler song in order to save energy to chase and try to court her at the same time."
Female Mice Respond Favorably to Male Mouse Calls
The female mice displayed varying reactions to the males’ songs. Most of them preferred listening to the more complex songs, and these distinctions give further validity that the songs carry meaning.
However, female mice don’t simply listen, they also respond with ultrasonic vocalizations of their own. For instance, both male and female mice are known to increase their vocalization rates during chases. It’s thought that a female’s participation in vocal communication may be a signal that she is receptive to the male’s advances.3
Interestingly, it’s also thought that ultrasonic vocalizations may carry some similarities to human speech. As reported in the journal Brain and Language:4
“Recent neurobiology studies have demonstrated that the mouse USV [ultrasonic vocalizations] brain system includes motor cortex and striatal regions, and that the vocal motor cortex sends a direct sparse projection to the brainstem vocal motor nucleus ambiguous, a projection previously thought to be unique to humans among mammals.
… we suggest that… mice possess some of the traits associated with a capacity for limited vocal learning.”
The findings of the featured study might even be applicable to autism research in humans. As Discovery News reported:5
“… the scientists plan to study how particular genes and brain areas play into the songs the mice are singing. If they can figure out to what degree mice can learn to modify their songs, they say, it could be helpful in the study of autism spectrum disorders, where social communication and brain circuitry that affects learned behavior are impacted.”
What Other Species Are Capable of Vocal Learning?
Most animals use sounds to communicate, but most are born with the knowledge of how to use them; it’s not a learned concept, per se. But research is uncovering that more animals than was previously expected may have some capacity for vocal learning – mice among them.
Killer whales also engage in vocal learning, a key aspect of language development, and will even learn to communicate with other species around which they’re raised, such as bottlenose dolphins.6
Bottlenose dolphins also engage in vocal learning and, unlike most other animals, develop their own vocal signature, or abstract “name,” early in life. This signature whistle sets each dolphin apart as an individual, and dolphins they are close to may mimic this whistle to essentially call them by name.
Birds also have unique vocal communications. A chickadee’s call, for instance, can reveal a warning about an imminent predator, along with clues as to the predator’s size and variety. Other animals in the forest eavesdrop on such calls, such that a squirrel’s warning call may save the life of a songbird – and vice versa.
Lyrebirds are also unique in their vocalizations, as they’re able to perfectly mimic the songs of other birds, plus koalas and dingoes – almost any sound in their environment. They have been recorded imitating a car’s engine, fire alarms, gunshots, dogs barking, babies crying, music, and even the human voice.
Mice Surprise Researchers with Their Vocal Similarities to Humans
As we discover more about the unique ways animals communicate, including vocal learning, it’s likely we’ll continue to uncover that humans are not the only ones with this complex ability.
Aside from humans, dolphins and songbirds, the fact that mice display this ability came as a surprise to researchers. Jarvis told Live Science:7
“The mouse brain and behavior for vocal communication is not as primitive and as innate as myself and many other scientists have considered it to be… Mice have more similarities in their vocal communication with humans than other species like our closest relatives [chimpanzees].”