An estimated 7,000 languages are spoken in the world but more than half of them are dying out so fast that they will be lost completely by the end of the century as children learn more common languages, such as English or Spanish. He cited the example of a South American skipper butterfly, Astraptes fulgerator, which scientists thought was just one species until a DNA study three years ago revealed that it was in fact 10 different species whose camouflaged colouration made the adult forms appear " identical to one another.

Yet if the scientists had spoken to the Tzeltal-speaking people of Mexico-descendants of the Maya-they might have leamt this information much sooner because Tzeltal has several descriptions of the butterflies based on the different kinds of caterpillar. "These people live on the territory of that butterfly habitat and in fact care very little about the adult butterfly but they have a very-fine grained classification for the larvae because the caterpillars affect their crops and their agriculture," Dr Harrison said.

"It's crucial for them to know which larva is eating which crop and at what time of year. Their survival literally depends on knowing that, whereas the adult butterfly has no impact on their crops," he said. "There was a knowledge gap on both sides and if they had been talking to each other they might have figured out sooner that they were dealing with a species complex," he said.

"Indigenous people often have classification systems that are often more fine-grained and more precise than what Western science knows about species and their territories." Another example of local knowledge was shown by the Musqueam people of British Columbia in Canada, who have fished the local rivers for generations and describe the trout and the salmon as belonging to the same group.

In 2003 they were vindicated when a genetic study revealed that the "trout" did in fact belong to the same group as Pacific salmon, Dr Harrison said. "It seems obvious that knowing more about species and ecosystems would put us in a better position to sustain those species and ecosystems," he said. "That's my argument, that the knowledge gap is vastly to the detriment of Western science. We know much less than we think we do."

4. Why does the author say that indigenous languages hold the key to saving endangered species?

5. What does Dr Harrison's example of a South American skipper butterfly tell us?

6. Explain in your own words the author's conclusion "that the knowledge gap is vastly to the detriment of Western science. We know much less than we think we do."

Questions 7-10

Graduates from under-privileged backgrounds are to challenge the elitism of the barristers' profession, under plans outlined today. Reforms aimed at challenging the dominance of the rich and privileged classes which are disproportionately represented among the membership of the Bar will tackle the decline in students from poorer backgrounds joining the profession. They include financial assistance as well as measures to end the "intimidating environment" of the barristers' chambers which young lawyers must join if they want to train as advocates.

The increasing cost of the Bar and a perception that it is run by a social elite has halted progress in the greater inclusion of barristers from different backgrounds. A number of high-profile barristers, including the prime minister's wife, Cherie Booth QC, have warned that without changes, the Bar will continue to be dominated by white, middle-class male lawyers.

In a speech to the Social Mobility Foundation think tank in London this afternoon, Geoffrey Vos QC, Bar Council chairman, will say: "The Bar is a professional elite, by which I mean that the Bar's membership includes the best-quality lawyers practicing advocacy and offering specialist legal advice in many specialist areas. That kind of elitism is meritocratic, and hence desirable.

"Unfortunately, however, the elitism which fosters the high-quality services that the Bar stands for has also encouraged another form of elitism. That is elitism in the sense of exclusivity, exclusion, and in the creation of a profession which is barely accessible to equally talented people from less privileged backgrounds."

Last month, Mr Vos warned that the future of the barristers' profession was threatened by an overemphasis on posh accents and public school education. Mr Vos said then that people from ordinary backgrounds were often overlooked in favour of those who were from a "snobby" background. People from a privileged background were sometimes recruited even though they were not up to the job intellectually, he added. In his speech today, Mr Vos will outline the "barriers to entry," to a career at the Bar and some of the ways in which these may be overcome.

The Bar Council has asked the law lord, Lord Neuberger of Abbotsbury, to examine how these barriers can be overcome, and he will publish his interim report and consultation paper before Easter. He is expected to propose a placement programme to enable gifted children from state schools to learn about the Bar, the courts and barristers at first hand.

The Bar Council is also working towards putting together a new package of bank loans on favourable terms to allow young, aspiring barristers from poorer backgrounds to finance the Bar vocational course year and then have the financial ability to establish themselves in practice before they need to repay.

These loans would be available alongside the Inns of Court's scholarship and awards programmes. Mr Vos will say today: "I passionately believe that the professions in general, and the Bar in particular, must be accessible to the most able candidates from any background, whatever their race, gender, or socioeconomic group. "The Bar has done well in attracting good proportions of women and racial minorities and we must be as positive in attracting people from all socioeconomic backgrounds."

7. What is the "elitism of the barristers' profession" in the United Kingdom?

8. What are the barriers for graduates from under-privileged families to become barristers?

9. Give a brief summary of Bar Council chairman Geoffrey Vos's view on elitism of the barrister's profession.

10. What are the measures of reform to help poorer graduates become barristers?