"I was surprised because I had been expecting mice that are different in physical shape," he said by telephone, adding that in fact the project had also produced "a mouse with short limbs and a tail like a dachshund."
The laboratory, directed by professor Takeshi Yagi at the Osaka University's Graduate School of Frontier Biosciences in western Japan, now has more than 100 "singing mice" for further research.
The team hopes they will provide clues on how human language evolved, just as researchers in other countries study songbirds such as finches to help them understand the origins of human language.
Scientists have found that birds use different sound elements, put them together into chunks like words in human languages and then make strings of them to sing "songs," that are subject to certain linguistic rules.
"Mice are better than birds to study because they are mammals and much closer to humans in their brain structures and other biological aspects," Uchimura said.
"We are watching how a mouse that emits new sounds would affect ordinary mice in the same group... in other words if it has social connotations," he said, adding that ordinary mice squeak mainly under stress.