Apes Lack Gene for Speech, Study Finds
Wed Aug 14, 2002 5:41 PM ET, By Maggie Fox
WASHINGTON (Reuters) -
A few key changes in a single gene help explain why people can talk while mice and apes cannot, researchers said on Wednesday.
The gene, called FOXP2, seems to be involved in the face and jaw movements necessary for speech, the researchers in Germany and Britain said.
What is surprising is that the gene is so similar in animals ranging from mice to orangutans to chimpanzees, with a relatively small change having emerged--just as modern humans did--between 120,000 and 200,000 years ago, the researchers report in this week's online issue of the journal Nature.
"It is not the gene that made language possible," geneticist Wolfgang Enard of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, stressed in a telephone interview.
He said it is probably one of many genes involved in speech and language, which are complex abilities.
But the gene is clearly important. Research last year found that people who lack two normal copies of the gene have considerable difficulty speaking. They not only make mistakes in grammar but cannot always articulate words clearly.
"If you have (only) one functional copy of the gene, as a human, you have problems with language and facial movements," Enard said.
Enard, Svante Paabo and colleagues at Max-Planck and Oxford University in Britain looked at the gene in mice, chimpanzees, orangutans and humans.
It is a highly conserved gene, meaning it has changed little in the 70 million years of evolution separating mice from people. But Enard said it still had "changed a little bit with two amino acid changes on the human lineage."
Genes are strings of code that determine the arrangement of amino acids, the building blocks of proteins. Proteins are the "workhorses" that underlie biological processes.
A slight amino acid change would alter the resulting protein and, as is the case with FOXP2, the consequences can be enormous.
Apes lack the structures to speak, even if they had language--which is hotly debated. Yet humans, who share more than 98% of their genes with chimps, are defined by their ability to speak and use language.
In a mouse, which does not seem to use facial expressions, the gene is probably involved in a lot of functions, Enard said. FOXP2 is expressed, meaning the gene is active, in all tissues that have been examined.
"We have not so many genes and many things that have to be done in the body," Enard said. "Most of the time a single gene will have several functions. FOXP2 is not an exception."
Enard said geneticists will be taking a long, hard look at FOXP2 now.
"The really hard part will be to find out what human FOXP2 does differently from other FOXP2s," he said.
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