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Study: Apes lack gene for speech

Discovery helps explain why humans can talk the talk

Although they can't speak like humans, orangutans, gorillas and other higher primates have their own forms of verbal communication and physical gestures.  

By Marsha Walton
CNN Sci-Tech

(CNN) -- A couple of changes in one gene about 200,000 years ago may be the reason apes still pound the ground -- and humans can recite poetry to communicate.

Scientists identified a gene last year called FOXP2, the first to be directly linked to language ability. Researchers then studied the gene and the protein it produces in humans, as well as in gorillas, chimps, orangutans and mice.

They discovered a slight amino acid change in the human protein, which was not found in any of the other animals. That change may be a big reason humans developed the face and jaw structures, which make the profound capabilities of speech and language possible.

Just how important is language to what makes us human?

"It is perhaps the most important feature," said Wolfgang Enard, who detailed these findings in the online edition of the British journal Nature. "It makes culture possible. This ability to transfer knowledge has had the most impact on civilization," said Enard, who worked with Svante Paabo and others at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.

While scientists worldwide labor to unlock the secrets of about 60,000 human genes, the case of FOXP2 includes a fascinating human element. Since 1990, a British family known only as "KE" has been the focus of intense study. Across three generations, about half of family members suffered from severe language and speech difficulties.

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Researchers found those KE family members with the drastic impairments did not have two normal copies of FOXP2. The one flawed copy, they believe, led to immobility of the lips, tongue, and mouth, which makes their speech garbled. They also have difficulty understanding language structure and grammar.

FOXP2, like many genes, is a multi-tasker. It's not only important for speech, but has been shown crucial for lung development in mice, and is needed for brain development.

Enard says the alteration of FOXP2 in humans likely became widespread between 120,000 and 200,000 years ago. It's during that time that anatomically "modern" humans developed. That suggests their growing language skills helped in the expansion and success of the human race.

Different forms of communication

Ancient speech and language didn't leave fossils, so there's a lot of speculation about how they progressed. As cooperation got more important, it's believed sign language developed, and was then replaced by speech as it became more flexible and efficient in communicating.

Gorillas and other great apes have their own forms of verbal communication and physical gestures, says Dawn St. George, director of conservation education at the Zoologicial Society of Milwaukee, Wisconsin.

"They have facial, hand, and verbal gestures to communicate danger, or the discovery of a food source," said St. George, an expert in the field of popular genetics in great apes. She says gorillas that interact with humans develop additional gestures, including hugs and other signs of affection.

But without the same physical structures as humans in the face, mouth, and larynx, says St. George, no amount of brain power will enable our nearest living relatives to talk.

There's still great debate about the sounds and "languages" of other species, from dolphins and whales to parrots or songbirds.

Enard said geneticists will be taking a deeper look at FOXP2, to find out what human FOXP2 does differently from other FOXP2s.

There are not that many differences between the DNA of a human and a chimp, or even between a human and a whale. But, as knowledge of FOXP2 is revealing, even a tiny number of DNA mutations -- can lead to hugely important physical differences.


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