Wolfgang Enard of the Max-Planck Institute for Evolutionary Anthropology believes he has found the genetic discrepancy in mice and humans that accounts for speech and language.

His team is studying the genomic differences that differentiate humans from their primate ancestors. When the human lineage split from chimpanzees, two amino acids were changed in the gene FOXP2 — a change that is thought to be associated with crucial aspects of speaking and understanding language.

“Changes in FOXP2 occurred over the course of human evolution and are the best candidates for genetic changes that might explain why we can speak,” said Enard in a press release announcing his findings, which were published in the May 29 edition of the journal Cell. “The challenge is to study it functionally.”

But, of course, that can’t be done in people or chimps. So the researchers introduced those genetic changes into the FOXP2 gene of mice, which is essentially identical to that of chimps (and therefore a good model to study the human version).

The research shows that mice bearing the “humanized gene” develop changes in brain circuitry that have been previously linked to speech. Another tantalizing clue: The genetically altered mouse pups — who appeared to be generally healthy — make different ultrasonic vocalizations when placed outside the comfort of their mothers’ nests.

The researchers write that it will now be important to further explore the basis of the gene’s impacts and possible relationship the evolution of humans and apes.

“More studies will be needed to clarify to what extent mouse vocalizations can model aspects of human speech evolution,” they write. “We are confident that concerted studies of mice, humans and other primates will eventually clarify if this is the case.”

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