Leading Article: Billions well-spent to stop us multiplying

THROUGHOUT human history, population growth has been linked with economic, cultural and technological development. When mankind first learnt how to grow crops, 10,000 years ago, there were just 10 million people in the world, roughly the number living in London today. This grew to 100 million by the time of Christ, and 2.5 billion by the middle of this century. Since then - less than a lifetime - it has more than doubled, to 5.5 billion. Now there are signs that human numbers, far from being a measure of success, will be our downfall.

Yet world population continues to grow. There will be well over 6 billion people by the end of the century and between 7.8 billion and 12.5 billion by the middle of the next. It is no understatement to say - as some of the world's most distinguished scientists warned earlier this year at the 'science summit' on world population in Delhi - that humanity is approaching a crisis point in terms of population, environment and development. Yet it is not too late to avert the worst effects of the impending crisis.

A comforting sign that human numbers can be limited even in the most difficult circumstances has come from several developing countries. From Sierra Leone to Thailand, a country where family size has now reached levels akin to those in Europe, it is clear that poverty is no barrier to women fulfilling their wish for smaller families.

Many critics of family planning policies in the developing world have long argued that it is important to address the issue of poverty before that of population. Men and women have large families as an insurance against poverty in old age, they suggest. But it is now evident from numerous surveys of mothers in poor countries that, given the opportunity, they would have had fewer babies than they did.

The industrialised world has the means to help them, in the form of safe contraceptives and effective family planning education. There is little evidence that religion affects the decision of women to limit the size of their families if they have the means to make a choice. (Catholic Spain and Italy have lower birth-rates than the UK.) It is not merely a question of providing contraceptives, but of improving the status of young women.

This time bomb is a global problem. Primary responsibility for defusing it must, in this post-

paternalist era, rest with the developing world. But it is the industrialised world that has the means and know-how to help to achieve population stability. The UN estimates that dollars 9bn ( pounds 6bn) is needed annually for that purpose. There could, arguably, be no better investment.