Skip to main content

Tiny evolutionary mutation led to 'language gene'

Thursday, November 12, 2009 PARIS: Two minute changes in a gene that is otherwise identical in humans and chimps could explain why we have full-fledged power of speech while other primates can only grunt or screech, scientists said on Wednesday.The findings may also point to new drug targets for hard-to-treat diseases that disrupt speech, such as schizophrenia and autism, they said.A decade ago, researchers discovered that members of an extended family beset with a rare inherited speech disorder all shared the same defect in a gene called FOXP2.Investigators then found that a small number of patients with another speech-related disease, developmental dysphasia, also had mutations in the gene.Separately, biologists studying FOXP2 in our closest evolutionary cousin, the chimpanzee, noticed that only two among the hundreds of amino acids in the protein coded by the gene differed across the two species.The question emerged: Could this minor genetic variation be the key that enables human speech?Some experts suggested the telltale pair of amino acids -- the building blocks of proteins -- were evidence of a "fast track" evolution toward language.Others, though, argued that the molecules played no part in our ability to yammer and yak.To find out who might be right, Daniel Geshwind, a professor at the University of California in Los Angeles, designed the first-ever experiments comparing the "ancestral" FOXP2 in chimps with the evolved variant in humans."We thought this would be a direct way to test the relevance of these two amino acids in the protein's function," Geschwind said while talking to a French news agency by phone.The lab tests focused on genetic expression, the process by which a gene's DNA sequence is converted into proteins.The researchers also looked at FOXP2's role as a "master gene" that activates or silences other genes."What we found is that FOXP2 drives these genes to behave differently in the two species," said Geschwind.In humans, the gene triggered changes in regions of cerebral cortex known to control high cognitive functions and language. Surprisingly, it also affected another part of the human brain, the striatum, involved in both cognition and motor coordination."We speculate that FOXP2 [in humans] might be involved in regulating both the neural motor mechanism of speech as well as some of the physical structure," said Geschwind.In other words, even if one could transplant a human brain into a chimpanzee, the ape would probably be unable to speak because it lacks the right "articulatory apparatus," he said.The findings hold real promise for the treatment of disorders that disrupt the ability to use language, the researchers said.Future research, for example, could scan the circuit of genes affected by FOXP2 for telltale mutations among patients afflicted with autism, schizophrenia or other speech disorders."We have been looking most for rare mutations, but I would look first at pure language disorders such as dyslexia," said Geschwind.Human speech is thought to have emerged 100,000 to 200,000 years ago, some five million years after chimps and humans took divergent paths on the tree of evolution.The study is published in the British science journal Nature.

Comments

Popular posts from this blog

India's swine flu death rate is increasing

Friday, August 14, 2009 MUMBAI: A 26-year-old woman died Thursday of H1N1 swine flu in the southern city of Bangalore, raising India's death toll from the virus to 20, authorities said.The death was the first reported in India's information technology capital, the Press Trust of India reported.Meanwhile in Pune, the worst-affected in India, two more victims of the virus died Thursday, raising the death toll in that western city near Mumbai to 12, the report said. The victims were an 11-month-old boy and a 75-year-old old woman.US media reported movie halls, schools and colleges were ordered closed Thursday for three days to a week in Mumbai, the commercial and financial capital of the country, as fear of the pandemic spread.Prajakata Lavangare, a spokeswoman for the government of Maharashtra state of which Mumbai is the capital, said similar orders were issued in Pune, which is also located in the state.The woman who died in Bangalore was identified only as Roopa, a teacher in...

Snake bite deaths

Monday, July 06, 2009 COLOMBO: The Sri Lankan government recorded some 33,000 snake bites in 2008, with most of the victims coming from remote villages.The Department of Government Information said in a statement that most of the snake bite cases could be fatal if neglected.The statement said snake bites are often neglected in Sri Lanka as victims do not seek treatment at hospitals where advanced medication is available. Instead, the victims rush to traditional type of treatment which could be a risk, reports Xinhua.Snake bites death at domestic level, outside hospitals, go unrecorded, said the statement.Most victims of snake bite are from the rural and remote villages where there is no electricity after dusk.Statistics show that Sri Lanka has over 90 species of snake with around 10 species possessing venom capable of killing a human being.In Sri Lanka the annual death rate due to snake bite envenoming is one of the highest in the world being 6 in 100,000 population.