July 21, 2010 Leave a comment
It’s true. They can sing
Male mice can sing. They aren’t exactly sitting underneath an open window on a moonlit night, guitar in hand, crooning an evening serenade to their lady love, but apparently, they do sing for the ladies.
Very few mammals sing. In fact, until the mouse discovery, we and whales were the only verified members of the mammalian choir. Scientists knew that mice vocalize; for example, mice that are surprised or in pain can emit sounds that humans can easily hear, under 30 kHz. Newborn mice can make sounds that their mothers recognize, summoning the dams to make them warm or return them to the nest. And male mice make ultrasonic sounds, above 30 kHz, that the human ear cannot hear. Usually, males make these sounds in response to the smell of an available female.
Birds, mice, whales, people
Because humans and whales make pretty large research animals and ethical issues prevent studies with either, research into how language is learned and how the brain transmits messages about language has relied on birdsong. You may not have thought about it much, but the song a bird sings is really a song, containing repeated melody lines or syllables, and the bird can repeat it given the necessary stimulus. But birds also must learn their songs, and the birds they’re trying to attract must be able to understand them. Because of this requirement for learning, birdsong has been the model for how mammals acquire and learn language.
Birds may be catching a break now, thanks to a recent breakthrough in mouse song. Researchers examined the vocalizations of 45 male mice by placing the mice in a recording chamber. The scientists then inserted through a tube a cotton swab soaked in enough female mouse urine to convince the male to burst into song. After recording the mouse’s vocalization, the researchers manipulated the recordings to so that humans could hear them and then analyzed them using software.
Gus-Gus, is that you?
What they report is that the mice appear to be singing actual songs that contain syllables—very rapidly produced syllables at about 10 per second. In addition, the songs had phrases that the animals would repeat. The mice all seemed to have their own individual songs, and almost all 45 mice sang in response to the urine stimulus.
That mice sing at all was discovered by accident, but the finding that they do sing what appear to be genuine songs opens up a multitude of research possibilities. Among directly related questions to address, scientists must examine how females respond to these calls and whether or not different experiences in fetal development affect the song or success of the song. In addition, scientists must try to demonstrate that the songs are truly learned if the mouse is to be used as a mammalian model for mammalian communication, replacing birdsong.
OK, that’s cute, but why is it relevant?
If the mouse song is learned, the animal will become an important model for these studies. Because mice have been used for decades in genetics studies, there are hundreds of different varieties of mice with genes knocked out or knocked in, and researchers can make their own special strains to assess the effects of a particular gene on song structure or production. We may be able to use this model to identify genes directly involved in learning and communication in mammals.
Identifying these genes could lead to investigations of how developmental processes and differences result in differential learning abilities. For example, people who are autistic exhibit altered communication skills. A stronger understanding of the genetics of mammalian communication may help us to unravel the underpinnings of this aspect of autism and other communication disorders.
These findings also lead to another question that remains to be addressed: Are there other animals that sing a secret song that our ears can’t hear?