Chimpanzees lack key parts of a language gene that is critical for human
speech, say researchers. The finding may begin to explain why only humans
use spoken language. Last year scientists identified the first gene, called
FOXP2, linked to human language. People with mistakes in this gene have
severe difficulties with speech and grammar.
Now Svante Paabo of the Max Planck Institute for Evolutionary Anthropology
in Leipzig, Germany, and his colleagues have compared human FOXP2 with
the versions of the gene found in the chimpanzee, gorilla, orang-utan,
rhesus macaque and mouse. Human FOXP2 contains two key changes in its
DNA compared with the other animals, the team found. "It changed
in the human lineage," says team member Wolfgang Enard.
The changes may affect the human ability to make fine movements of the
mouth and larynx, and thus to develop spoken language, Enard suggests.
"It's fascinating," says Martin Nowak, who studies the evolution
of language at the Institute for Advanced Study in Princeton. "It's
the beginning of a genetic foundation for human language."
Language is unique to humans: chimpanzees can be trained to communicate
using a complex set of symbols, but they can pronounce only a handful
of words because they cannot make the required facial movements. The gene
variant that permits language may have become widespread during the last
200,000 years, Enard estimates, based on analyses of the human gene from
individuals worldwide. It was around this time that anatomically modern
humans emerged. The development of language may have been an important
driving force behind human expansion. It allowed large amounts of information
to be passed from one generation to the next, explains Nowak.
Researchers are not yet clear what the FOXP2 gene does, but they think
it acts by switching other genes on and off. The two changes aside, the
gene is almost identical in humans and the other animals examined.
1.Lai, C.S.L. et al. A forkhead-domain gene is mutated in severe speech
and language disorder. Nature, 413, 519 - 523, (2001).
2.Enard, W. et al. Molecular evolution of FOXP2, a gene involved in speech
and language. Nature, published online, doi:10.1038/nature01025 (2002).
Nature News Service / Macmillan Magazines Ltd 2002
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