From Science:
For the first time, scientists have compared a vast network of human genes responsible for speech and language with an analogous network in chimpanzees. The findings help shed light on how we moved beyond hoots and grunts to develop vast vocabularies, syntax, and grammar.
The centerpiece of the study is FOXP2, a so-called transcription factor that turns other genes on and off. The gene rose to fame in 2001 when researchers showed that a mutant form of it caused an inherited speech and language problem in three generations of the “KE family” in England. The following year, researchers showed that normal FOXP2 differed by only two amino acids–the building blocks of proteins–between humans and chimpanzees. Analyzing more ancestral species, they further showed that the gene was highly conserved all the way up to chimps, suggesting that it played a prominent role in our unique ability to communicate complex thoughts.
More here.