India's Parsis served both the Raj and the battle for independence, built many of the country's commercial legends, and gave the world Freddie Mercury, but the fire-worshipping community is now facing its greatest challenge - staving off extinction. Faced with falling birth rates and growing emigration to the west, 1,000 years of rich history is looking increasingly frail. In 1941 there were 114,500 Parsis in India, mainly living in Mumbai and the surrounding area. That figure has fallen to less than 70,000, according to recent census results, and is expected to drop to 21,000 by 2021. Leading Parsis fear a unique culture may be gone within a century. 'Over the past 200 years the contribution of the Parsis to the development of India and Mumbai in particular has been out of this world,' said retired army general A.M. Sethna, president of the Delhi Parsi Anjuman. 'But since the 1950s we have had more deaths than births. That's a fact of life, but it's one many Parsis seem unable to accept. They don't see that too many of us have grey hair.' Thirty-one per cent of the population is now over 60. Every year there are 900 deaths and only 300 births. According to a Tata Institute of Social Studies report, 40 per cent of Parsi men and women are unmarried, and an offer by the community's governing body, the Parsi Panchayat, of a monthly bonus for having a population-boosting third child has failed to attract many takers. Adding to their woes is a desperate attempt to maintain what the eight Parsi high priests term the religion's 'purity'. While the children of Parsi men who marry outside the community are welcome in the fire temples, if a woman marries a non-Parsi - and more than 30 per cent now do so - her children are usually lost to the faith forever. The Parsis are followers of the 6th-century BC Persian prophet Zoroaster, the world's first monotheistic prophet, and are named after the city of Pars in what is today southern Iran. Zoroastrians worship fire as the purest symbol of the divine and the creator of life. Alexander the Great - to Zoroastrians he is known as Alexander the Accursed - destroyed almost all the written texts of Zoroastrianism in 331BC during the conquest of the Persian empire, and Zoroastrians have since depended almost entirely on their oral traditions. The faith travelled as far as northern China, but persecuted by invading Arab Muslims 1,400 years ago, many Zoroastrians fled their homelands and others converted to Islam. There are thought to be no more than 150,000 left in the world, living mainly in India, Iran and North America. In the eighth century many found their way to Gujarat in north India. At first the Parsis were given refuge by Hindu kings on condition that they abstain from proselytising and marry only within their community. The Parsis still speak a dialect of Gujarati. Mumbai later became the centre of their world, where they built fire temples and the famous 'Towers of Silence' where the dead are left naked to be devoured by vultures. The practice has its origins in a belief that the dead should not pollute the earth, but has been hit by a rapidly falling vulture population that scientists have linked to the use of certain painkilling drugs in livestock whose carcasses are eaten by the birds. Some of the towers have now been fitted with solar reflectors to speed up decomposition. Settled in India, the Parsis became farmers and small-time businessmen but came to prominence with the advent of British rule when they became known as the 'Jews of India'. Before long they were dominating business in Victorian Bombay and building the city's first hospitals and universities. Lighter skinned, educated and sexually equal, the Parsis fitted well into the post-mutiny British ambition to westernise India. With a few exceptions - most notably Dadabhai Naoroji, an early supporter of the independence movement and later president of the Indian National Congress - they remained loyal to their colonial masters and prospered. The giant Tata conglomerate, formed by Parsi Jamshetji Nusserwanji Tata, is so huge it built its own city, Jamshedpur, near Calcutta. The organisation laid the foundations for India's economic independence in major industries such as steel and textiles, and launched the country's first airline which later became Air India. The firm built one of Mumbai's best-known landmarks, the Taj Mahal hotel, in 1903. Several other major firms still operating today have Parsi roots. The parents of the Parsi who the world would know as Freddie Mercury moved to Mumbai from Zanzibar, where the former Queen lead singer was born in 1947. The community has also produced composer and former New York philharmonic conductor Zubin Mehta, and novelist Rohinton Mistry. But the golden days are over. As members of an emancipated and educated community, Parsis are leaving India, choosing a career over family, having fewer children and marrying outside the fold. 'We are paying the penalties of progress,' said General Sethna, 80. 'It's a reflection of what is happening in the west.' In an attempt to halt the community's seemingly terminal decline, leaders are questioning the sense of having such strict laws on who is and is not a Parsi. According to General Sethna, conversion was positively encouraged in the Persian empire before the Islamic invasions, but on arrival in predominantly Hindu India that freedom to recruit new followers and hence marry outside the faith was lost. 'After coming to India, there is not a single instance of conversion,' said Jehangir Patel, editor of the Mumbai-based monthly magazine Parsiana. 'Here the Hindu caste system dominated so we took on the appearance of a caste to keep the community intact.' The courts strengthened this feeling of isolation when in 1908 they turned down an appeal from the French mother of J.R.D. Tata, a grand nephew of Jamshetji, to be allowed to enter the fire temple. The judges ruled that the Parsi community might have veered from Zoroastrian orthodoxy, but that the wishes of the community's founding fathers should be respected. 'At the moment anyone can convert and become a Zoroastrian, but to be a Parsi you have to have a Parsi father. Until one of our women challenge this court ruling nothing will change,' said Patel. In Delhi, Chennai and elsewhere in India tiny Parsi communities have relaxed the rules and thrown open the doors of the fire temple for children of all inter-faith marriages, as long as the non-Parsi parent agrees. But Mumbai's traditionalists are holding out for now. 'The genealogy must remain intact,' Firoze Kotwal, a high priest in the city, said recently. 'I am optimistic that the community will be vibrant and alive until the day of resurrection.' Either way the writing is on the wall, it seems. 'Probably nothing will make much difference,' said General Sethna. 'But at least we should be able to fight a rearguard action.'