The present state of the whole of the human species in relation to its total environment is so vast a topic that cautious and discriminating people might well avoid it as the subject of a single, short paper. It is, after all, a major area of concern for many sciences—social, biological, and technological. I take it as my subject here not, I hope, because I am incautious or undiscriminating, but because the ecology of any species, no matter how complex its behavior, can justifiably be regarded as unitary, and should therefore be reviewed as a whole from time to time. Furthermore, I would hold that the predicament of our species at the present time makes such a review not only desirable but vital.
Following an evolution of hundreds of millennia, Homo sapiens emerged on the post-glacial scene as a dominant species with almost world-wide distribution. Clearly his numbers had increased only very slowly over this vast period of time, and it was not until around A.D. 1810 (Table I) that a world population of one billion was first achieved.
Only just over a century then elapsed before the species had added just as many again to its numbers, the two billion mark being passed just after 1920. Then, in less than forty years, another increment of the same magnitude was added by the end of 1960.
If the growth rate of the decade 1950-60 were to be continued up to A.D. 2000, projection indicates the addition of further increments of one billion by the years 1975, 1984, 1992, and 1998, and a total of 7.41 billion by the end of the century^2.
In fact it seems unlikely that such a growth rate could be sustained. Nevertheless, realistic projections made in 1963 still indicated a vast population increase by the year 2000; projections for that year varied between 5.30 billion and 6.83 billion according to the assumptions made, but medium assumptions indicated a population of four billion by about 1977, five billion by about 1990, and 5.96 billion by the end of the century (Fig. 2).
Furthermore, there are now clear indications that, in the absence of disasters on a world scale, these 1963 medium estimates will be far exceeded and that the world population in A.D. 2000 will be more than double that in 1960.
A biologist presented with this graph of population increase would diagnose a “swarming stage” situation. there may be a great increase in predators; or there …