Humans more attuned to hearing language than chimps: study

Hearing genes seem to set people apart from chimpanzees, humanity's closest living relative.

The human genome is about 99 per cent identical to the chimp genome.

Researchers compared human, mouse and chimp gene maps to look for key differences.

The genetic variations may have helped tune our ears to spoken language, said Andrew Clark of Cornell University, Michelle Cargill of Celera Diagnostics in Alameda, Calif., and their colleagues

"Speech is considered to be a defining characteristic of humans," they wrote in Friday's issue of the journal Science. Chimpanzees use gestures to communicate.

"Several genes involved in the development of hearing also appear to have undergone adaptive evolution in the human lineage, and we speculate that understanding spoken language may have required tuning of hearing acuity."

Scientists consider mutations that confer an evolutionary advantage to be adaptive evolution.

By comparing the two primate genomes to that of the mouse, the researchers found the human senses of hearing and smell evolved more quickly.

To check if the genes distinguished the species, they also compared many of the genes between different people. The chimp genes had 10 times the differences.