Perhaps the most significant aspect of present day population growth and natural resource depletion is that both are on a scale quite without historical precedent. It is, of course, a great temptation in situations of this kind to project the likely future state of affairs which will come about if current trends are maintained, usually with rather gloomy results. Now it is well known that forecasting is a hazardous business, be it concerned with the weather or the level of economic activity. But this has not deterred a substantial and diverse group of physical and social scientists, supported by a large, if rather disparate, lay chorus, from asserting that explosive population growth in the third world and the levels of exploitation of non-renewable resources in the developed countries are combining to produce a set of conditions which are beyond the 'capacity of the planet' to sustain in the long run.

Despite the crude nature of the assumptions on which these projections are based, it has to be conceded that there is some force to them. The pity is that rational debate has been made more difficult by the strident and lurid tone of much of the language of the 'environmentalists'.

For example, one physicist calculated that if Adam and Eve had lived 10,000 years ago, and if they and their descendents had procreated at a compound rate of just 1 er cent per annum, the human race would now be a sphere of living flesh several galaxies in diameter, expanding radially at the speed of light -- if such were relativistically possible.