A DEMOGRAPHY AND STRESS: ADAPTATION AND STRESS

Currently the two greatest problems facing humankind, problems which link environmental, health and social issues, are population growth and the urgent need for its control. As Paul Ehrlich (from Stanford University) has stated so succinctly: ‘We are now in charge of the planet, but we are not behaving as if we know we are in charge of the planet’. Certaintly, we are not behaving in a manner that befits our special responsibilities, and, further, it seems that we are unwilling or unable to cope with our increasing numbers and the effect this increase has on our environment. The world's population is currently increasing at a rate of 90–100 million people a year, an increase of more than 10000 people every hour. In 1990 there were over 5 billion people on this planet. As a species, it took 4 million years for the world's population to grow from just over zero to 2 billion in 1932. Then, in less than six decades, it reached the 1989 figure of 5.2 billion. The present projection tells us that there will be more than 6 billion humans by the year 2000 and 7 billion by 2010 (Fig. 13.1). The impact of a growth rate can be better appreciated by the time taken for the population to double its size. Table 13.1 shows the approximate doubling times at various growth rates. Growth rates of 2% (a doubling time of 35 years) is particularly relevant since large parts of the world have a growth rate close to 2%.