As the world population reaches seven billion people, the BBC's Mike Gallagher asks whether efforts to control population have been, as some critics claim, a form of authoritarian control over the world's poorest citizens.
The temperature is some 30C. The humidity stifling, the noise unbearable. In a yard between two enormous tea-drying sheds, a number of dark-skinned women patiently sit, each accompanied by an unwieldy looking cloth sack. They are clad in colourful saris, but look tired and shabby. This is hardly surprising - they have spent most of the day in nearby plantation fields, picking tea that will net them around two cents a kilo - barely enough to feed their large families.
Vivek Baid thinks he knows how to help them. He runs the Mission for Population Control, a project in eastern India which aims to bring down high birth rates by encouraging local women to get sterilised after their second child.
As the world reaches an estimated seven billion people, people like Vivek say efforts to bring down the world's population must continue if life on Earth is to be sustainable, and if poverty and even mass starvation are to be avoided.
There is no doubting their good intentions. Vivek, for instance, has spent his own money on the project, and is passionate about creating a brighter future for India.
But critics allege that campaigners like Vivek - a successful and wealthy male businessman - have tended to live very different lives from those they seek to help, who are mainly poor women.
These critics argue that rich people have imposed population control on the poor for decades. And, they say, such coercive attempts to control the world's population often backfired and were sometimes harmful.
Most historians of modern population control trace its roots back to the Reverend Thomas Malthus, an English clergyman born in the 18th Century who believed that humans would always reproduce faster than Earth's capacity to feed them.
Giving succour to the resulting desperate masses would only imperil everyone else, he said. So the brutal reality was that it was better to let them starve.
Rapid agricultural advances in the 19th Century proved his main premise wrong, because food production generally more than kept pace with the growing population.
But the idea that the rich are threatened by the desperately poor has cast a long shadow into the 20th Century.
From the 1960s, the World Bank, the UN and a host of independent American philanthropic foundations, such as the Ford and Rockefeller foundations, began to focus on what they saw as the problem of burgeoning Third World numbers.
The believed that overpopulation was the primary cause of environmental degradation, economic underdevelopment and political instability.
Massive populations in the Third World were seen as presenting a threat to Western capitalism and access to resources, says Professor Betsy Hartmann of Hampshire College, Massachusetts, in the US.
"The view of the south is very much put in this Malthusian framework. It becomes just this powerful ideology," she says.
In 1966, President Lyndon Johnson warned that the US might be overwhelmed by desperate masses, and he made US foreign aid dependent on countries adopting family planning programmes.
Other wealthy countries such as Japan, Sweden and the UK also began to devote large amounts of money to reducing Third World birth rates.
What virtually everyone agreed was that there was a massive demand for birth control among the world's poorest people, and that if they could get their hands on reliable contraceptives, runaway population growth might be stopped.
But with the benefit of hindsight, some argue that this so-called unmet need theory put disproportionate emphasis on birth control and ignored other serious needs.
"It was a top-down solution," says Mohan Rao, a doctor and public health expert at Delhi's Jawaharlal Nehru University.
"There was an unmet need for contraceptive services, of course. But there was also an unmet need for health services and all kinds of other services which did not get attention. The focus became contraception."
Had the demographic experts worked at the grass-roots instead of imposing solutions from above, suggests Adrienne Germain, formerly of the Ford Foundation and then the International Women's Health Coalition, they might have achieved a better picture of the dilemmas facing women in poor, rural communities.
"Not to have a full set of health services meant women were either unable to use family planning, or unwilling to - because they could still expect half their kids to die by the age of five," she says.
Us and them
In 1968, the American biologist Paul Ehrlich caused a stir with his bestselling book, The Population Bomb, which suggested that it was already too late to save some countries from the dire effects of overpopulation, which would result in ecological disaster and the deaths of hundreds of millions of people in the 1970s.
Instead, governments should concentrate on drastically reducing population growth. He said financial assistance should be given only to those nations with a realistic chance of bringing birth rates down. Compulsory measures were not to be ruled out.
Western experts and local elites in the developing world soon imposed targets for reductions in family size, and used military analogies to drive home the urgency, says Matthew Connelly, a historian of population control at Columbia University in New York.
"They spoke of a war on population growth, fought with contraceptive weapons," he says. "The war would entail sacrifices, and collateral damage."
Such language betrayed a lack of empathy with their subjects, says Ms Germain: "People didn't talk about people. They talked of acceptors and users of family planning."
Critics of population control had their say at the first ever UN population conference in 1974.
Karan Singh, India's health minister at the time, declared that "development is the best contraceptive".
But just a year later, Mr Singh's government presided over one of the most notorious episodes in the history of population control.
In June 1975, the Indian premier, Indira Gandhi, declared a state of emergency after accusations of corruption threatened her government. Her son Sanjay used the measure to introduce radical population control measures targeted at the poor.
The Indian emergency lasted less than two years, but in 1975 alone, some eight million Indians - mainly poor men - were sterilised.
Yet, for all the official programmes and coercion, many poor women kept on having babies.
And where they did not, it arguably had less to do with coercive population control than with development, just as Karan Singh had argued in 1974, says historian Matt Connelly.
For example, in India, a disparity in birth rates could already be observed between the impoverished northern states and more developed southern regions like Kerala, where women were more likely to be literate and educated, and their offspring more likely to be healthy.
Women there realised that they could have fewer births and still expect to see their children survive into adulthood.
By now, this phenomenon could be observed in another country too - one that would nevertheless go on to impose the most draconian population control of all.
The One Child Policy is credited with preventing some 400 million births in China, and remains in place to this day. In 1983 alone, more than 16 million women and four million men were sterilised, and 14 million women received abortions.
Assessed by numbers alone, it is said to be by far the most successful population control initiative. Yet it remains deeply controversial, not only because of the human suffering it has caused.
A few years after its inception, the policy was relaxed slightly to allow rural couples two children if their first was not a boy. Boy children are prized, especially in the countryside where they provide labour and care for parents in old age.
But modern technology allows parents to discover the sex of the foetus, and many choose to abort if they are carrying a girl. In some regions, there is now a serious imbalance between men and women.
Moreover, since Chinese fertility was already in decline at the time the policy was implemented, some argue that it bears less responsibility for China's falling birth rate than its supporters claim.
"I don't think they needed to bring it down further," says Indian demographer AR Nanda. "It would have happened at its own slow pace in another 10 years."
In the early 1980s, objections to the population control movement began to grow, especially in the United States.
In Washington, the new Reagan administration removed financial support for any programmes that involved abortion or sterilisation.
The broad alliance to stem birth rates was beginning to dissolve and the debate become more polarised along political lines.
While some on the political right had moral objections to population control, some on the left saw it as neo-colonialism.
Faith groups condemned it as a Western attack on religious values, but women's groups feared changes would mean poor women would be even less well-served.
By the time of a major UN conference on population and development in Cairo in 1994, women's groups were ready to strike a blow for women's rights, and they won.
The conference adopted a 20-year plan of action, known as the Cairo consensus, which called on countries to recognise that ordinary women's needs - rather than demographers' plans - should be at the heart of population strategies.
Today's record-breaking global population hides a marked long-term trend towards lower birth rates, as urbanisation, better health care, education and access to family planning all affect women's choices.
With the exception of sub-Saharan Africa and some of the poorest parts of India, we are now having fewer children than we once did - in some cases, failing even to replace ourselves in the next generation. And although total numbers are set to rise still further, the peak is now in sight.
Assuming that this trend continues, total numbers will one day level off, and even fall. As a result, some believe the sense of urgency that once surrounded population control has subsided.
The term population control itself has fallen out of fashion, as it was deemed to have authoritarian connotations. Post-Cairo, the talk is of women's rights and reproductive rights, meaning the right to a free choice over whether or not to have children.
According to Adrienne Germain, that is the main lesson we should learn from the past 50 years.
"I have a profound conviction that if you give women the tools they need - education, employment, contraception, safe abortion - then they will make the choices that benefit society," she says.
"If you don't, then you'll just be in an endless cycle of trying to exert control over fertility - to bring it up, to bring it down, to keep it stable. And it never comes out well. Never."
Nevertheless, there remain to this day schemes to sterilise the less well-off, often in return for financial incentives. In effect, say critics, this amounts to coercion, since the very poor find it hard to reject cash.
"The people proposing this argue 'Don't worry, everything' s fine now we have voluntary programmes on the Cairo model'," says Betsy Hartmann.
"But what they don't understand is the profound difference in power between rich and poor. The people who provide many services in poor areas are already prejudiced against the people they serve."
Work in progress
For Mohan Rao, it is an example of how even the Cairo consensus fails to take account of the developing world.
"Cairo had some good things," he says. "However Cairo was driven largely by First World feminist agendas. Reproductive rights are all very well, but [there needs to be] a whole lot of other kinds of enabling rights before women can access reproductive rights. You need rights to food, employment, water, justice and fair wages. Without all these you cannot have reproductive rights."
Perhaps, then, the humanitarian ideals of Cairo are still a work in progress.
Meanwhile, Paul Ehrlich has also amended his view of the issue.
If he were to write his book today, "I wouldn't focus on the poverty-stricken masses", he told the BBC.
"I would focus on there being too many rich people. It's crystal clear that we can't support seven billion people in the style of the wealthier Americans."
Mike Gallager is the producer of the radio programme Controlling People on BBC World Service