Cell 137, 961–971 (2009)

Mice carrying a humanized version of a gene considered key to the human capacity for speech show subtle changes in their brains and in the way they vocalize.

Wolfgang Enard of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and his colleagues substituted two amino acids in the mouse Foxp2 protein to generate the humanized version. The animals remained generally healthy, but calls made by isolated pups had a different structure from those of normal mouse pups.

The authors also found structural, neurochemical and neurophysiological changes to neurons in a brain circuit associated with speech in humans. They say it could represent the first investigation, in an animal model, of amino-acid substitutions that might be relevant to human evolution.