Of the 20,000 genes in the human genome, few are more fascinating than FOXP2, a gene that underlies the faculty of human speech.

All animals have an FOXP2 gene, but the human version’s product differs at just 2 of its 740 units from that of chimpanzees, suggesting that this tiny evolutionary fix may hold the key to why people can speak and chimps cannot.

FOXP2 came to light in a large London family, half of whose members have severe problems in articulating and understanding speech. All turned out to have a mutation that disrupted this vital gene.

This year, one inquiry bore fruit, although of a somewhat ambiguous nature, when biologists in Leipzig, Germany, genetically engineered a mouse with the human version of FOXP2 substituted for its own. The upgraded mice squeaked somewhat differently from plain mice and were born with subtle alterations in brain structure. But mice and people are rather distant cousins  their last common ancestor lived some 70 million years ago  and the human version of FOXP2 evidently was not able to exert a transformative effect on the mouse.